The present invention concerns a system for coupling safety apparatuses, in particular safety apparatuses configured to create a protecting barrier, optionally an intangible barrier, for instance an optical barrier, to mechanical working machines, e.g. press brakes, comprising at least one movable part configured to move with respect to at least one fixed part, which coupling system allows in an efficient, reliable, simple and inexpensive way to position with high precision at least one component of a safety apparatus in correspondence with the at least one movable part of the machine and to simultaneously protect an operator from the consequences of possible undue impacts of the same safety apparatuses, for instance on parts of the operator's body, on tools or materials malpositioned on the machine, or objects inappropriately introduced and/or positioned in proximity of the machine, further avoiding possible breakages, faults and positioning changes of the safety apparatuses caused by such impacts.

In the following of this description, reference will be mainly made to the application of the coupling system according to the invention to a press brake in order to position a safety apparatus creating a protecting laser optical barrier. However, it must be noted that the coupling system according to the invention may be applied to any mechanical working machine having at least one movable part that, during the machine operation intended for mechanical working and/or during a preliminary phase of delimiting a protection zone, moves according to a translational and/or rotational motion with respect to at least one fixed part (in particular, along at least one direction along which the weight force acting on the safety apparatus has a nonzero component), such as for instance guillotine shears, milling machines, and polishing machines, still remaining within the scope of protection of the present invention as defined by the attached claims. It must be further noted that the system according to the invention may be used for coupling any safety apparatus to the mechanical working machine, both a safety apparatus with intangible barrier different from a laser optical barrier (e.g. with highly directional radiofrequency beams which sense modification of a capacitance of an electric circuit) and a safety apparatus with physical barrier (e.g. an interlocked barrier mounted on at least one movable part of the machine that remains still during the operation of the latter and that moves, along at least one direction along which the weight force acting on the safety apparatus has a non-zero component, during a preliminary phase of delimiting a protection zone for closing the access to an hazardous area of the machine before the latter starts to operate - in this case the movable part of the machine on which the interlocked barrier is mounted may be different from the machine parts operating the mechanical working), still remaining within the scope of protection of the present invention as defined by the attached claims.

It is known that, among the mechanical working machines, press brakes are employed in processes for bending sheet metal.

A press brake comprises a top movable part, provided with a top tool called punch, that during the machine operation moves according to a translational motion in vertical direction with respect to a bottom fixed part, provided with a bottom tool called die. I n particular, the machine operation and, specifically, the translational motion (usually actuated by hydraulic means) of the movable part and, consequently, of the punch, is controlled by a control electronic unit connected to an interface, e.g. a control panel provided with one or more buttons, through which interface an operator interacts with the control electronic unit to operating the controls for the operation and stop of the press brake. Generally, both the punch and the die are not integral part of the movable part and the fixed part, respectively, rather they are mounted on these, so as to allow the press brake to be equipped with a punch-die pair selected from a set comprising a plurality of such pairs, so as to permit to bend various thickness metal sheet obtaining different bending outlines.

The bending process is performed by an operator positioning the sheet metal to bend on the die (where the exact positioning of the sheet metal to bend may be obtained with the aid of positioning elements) and interacting with the control panel (or other interface) per causing the punch to move down towa rds the die, so as to deform the sheet metal and obtain the bending according to an outline determined by the profiles of the specific punch-die pair used. Afterwards, the punch is moved up and spaced apart from the die, allowing the operator to move the sheet metal, so as to proceed to obtain a new bending line on the same sheet metal or another sheet metal that is positioned on the die after that the previous one has been removed.

During the bending process, the operators are subject to some risks due to the possibility that a body part enters the hazardous area of the press brake. By way of example and not by way of limitation, an operator's hand or finger may undergo a crushing or even a shearing by the punch, or an operator's body part, such as the head, shoulder or torso, may suffer an impact from the punch and/or the movable part.

In order to eliminate, or at least to greatly reduce, such risks for operators, the press brakes are equipped with safety apparatuses forming physical and/or intangible protecting barriers. Physical barriers may comprise shields and shelters delimiting a protection zone and preventing unauthorised personnel from accessing the hazardous area of the press brake during press brake operation. The intangible barriers are generated by optoelectronic apparatuses forming optical barriers by means of one or more light beams delimiting the protection zone in correspondence with the hazardous area (wherein a hazardous situation is detected when a light beam is interrupted), and/or by electronic apparatuses forming barriers through highly directional radiofrequency beams delimiting the protection zone in correspondence with the hazardous area (e.g., wherein a hazardous situation is detected when a capacitance in an electronic circuit of the apparatus is modified).

In the last decades, the safety apparatuses forming optical barriers, in particular by generating one or more laser beams, have been increasingly used for press brakes. A laser beam safety apparatus generally comprises a device emitting one or more laser beams and a device receiving said one or more laser beams, which are mounted laterally on the movable part so that said one or more laser beams are in proximity of the punch to form a protecting barrier (since the volume surrounding the punch is a hazardous area), as well as a control electronic device that is connected to the control electronic unit of the press brake so as to stop and prevent the movement of the movable part of the press brake when the receiving device senses an interruption of one of said one or more laser beams. In this regard, the control electronic device may receive from the control electronic unit of the press brake information related to the position of the punch from the die, i.e. related to the distance of the former from the latter, whereby the operating configuration of the laser safety apparatus may be set so as to allow such stop intervention by the control electronic device only when the punch (or the movable part) is at a distance from the die (or from the fixed part) lower or not larger than a threshold value.

For mounting each one of the emitting and receiving devices to the movable part of the press brake, coupling systems provided with manual or powered positioning devices are used for appropriately positioning the emitting and receiving devices, which must be aligned with each other so that the laser beams emitted by the first one are correctly received by the second one.

Figure 1 shows a prior art coupling system, similar to those disclosed by documents

W09725568Al and DE19717299A1. The coupling system of Figure 1 couples a device 1 of a laser safety apparatus to the movable part 2, on which a punch 3 is mounted, of a press brake, of which also the fixed part 4 is shown, provided with a die 5; in particular, the device 1 may be both the laser beam emitting device and the laser beam receiving device of the laser safety apparatus, the coupling system being in any case the same for the two devices (at least in relation to the mechanical components thereof).

The coupling system of Figure 1, that is provided with a powered positioning device, comprises a fixing bracket 106 having a first end 107 fixed to the movable part 2 of the press brake and a second end 108 housed within a tubular element 109 at the lower end 110 of which the device 1 of the laser safety apparatus is fixed.

The second end 108 of the fixing bracket 106 is connected to the powered positioning device, that comprises a worm 111 interacting with the internal thread of a through hole (not shown) of the second end 108, which worm 111 is rotated by a motor 112 housed in the upper end of the tubular element 109 (even if the motor 112 could be mounted in any position inside or outside the tubular element 109). When the motor 112 rotates the worm 111, the interaction of this with the internal thread of the through hole of the second end 108 of the fixing bracket 106 causes a vertical translational motion of the tubular element 109 with respect to the fixing bracket 106, represented in Figure 1 by bidirectional arrow A, and consequently a vertical translational motion of the device 1 with respect to the movable part 2 and the punch 3 of the press brake, thus allowing an accurate positioning of the device 1 with respect to the volume surrounding the punch 3; the reciprocal sliding between the second end 108 and the tubular element 109 is usually assisted by guides (not shown) inside the tubular element 109. Obviously, the direction of rotation of the worm 111 determines whether the vertical translational motion of the tubular element 109 is upwards or downwards. Also, the tubular element 109 is shaped so as to allow its translational motion with respect to the fixing bracket 106 (e.g., the tubular element 109 may comprise a vertical groove on the side wall facing the movable part 2 of the press brake, within which vertical groove the fixing bracket 106 may slide).

Through the prior art coupling system, shown by way of example in Figure 1, the device 1 of the laser safety apparatus is anchored to the movable part 2 of the press brake. This entails that, during the translational motion of the movable part 2 with respect to the fixed part 4, represented in Figure 1 by bidirectional arrow B, the whole assembly comprising the device 1, the tubular element 109 and the fixing bracket 106, that is integrally coupled to the movable part 2, moves along with it.

However, the prior art coupling systems suffer from some drawbacks, due to a lack of protection from the impacts of the device 1 that is integrally coupled to the movable part 2 of the press brake.

In fact, if during the descent phase of the movable part 2 an obstacle is present below the device 1 of the safety apparatus, for instance the bottom tool 5 malpositioned on the fixed part 4, as shown by way of example in Figure 2, a hazardous situation is created for the operator the finger (or hand) of whom, for instance, could remain crushed with extreme force between the device 1 and the bottom tool 5; also, the device 1, by impacting the bottom tool 5 malpositioned on the fixed part 4, could cause the bottom tool 5 to overturn and/or hit the operator and/or be damaged. Similar hazardous situation occur for instance in the case where the obstacle improperly positioned below the device 1 of the safety apparatus is a projecting portion of the sheet metal to bend or any object improperly resting laterally to the fixed part 4 of the press brake.

Furthermore, should the operator (or another person) be improperly below the device 1 of the safety apparatus during the descent phase of the movable part 2, a hazardous situation is created again for the operator (or another person) since the latter could be hit by the same device 1.

Therefore, it is an object of the present invention to allow in an efficient, reliable, simple and inexpensive way to couple at least one component of a safety apparatus to at least one movable part of a mechanical working machine so as to position with high precision said at least one component of the safety apparatus in relation to said at least one movable part and to simultaneously protect an operator from the consequences of possible hazardous impacts of the same safety apparatuses, for instance on body parts of the same operator, on tools or materials malpositioned on the machine, or objects inappropriately introduced and/or positioned in proximity of the machine, further avoiding possible breakages, faults and positioning changes of the safety apparatuses caused by such impacts.

It is specific subject matter of the present invention a coupling system for coupling safety apparatuses to a movable part of a mechanical working machine, comprising:

a fixing bracket having a first end configured to be fixed to a movable part of a mechanical working machine,

- a tubular element configured to be coupled to at least one component of a safety apparatus, and

a plate provided with a through hole having an internal thread, wherein the fixing bracket further has a second end provided with an idle slider assembly configured to slide along one or more first linear guide elements of at least one side wall of the tubular element, wherein the tubular element comprises a worm interacting with the internal thread of the through hole of the plate, and wherein the plate is provided with one or more sliding elements configured to slide within respective one or more second linear guide elements with which the tubular element is provided, which are parallel to said one or more first linear guide elements, whereby the plate slides within the tubular element when the worm rotates, the plate being configured to be stably resting on the fixing bracket when the plate is subject to a weight force of the plate and of the tubular element, whereby the tubular element is constrained to follow a translationa! motion of the fixing bracket only in one direction going from the fixing bracket to the plate.

According to another aspect of the invention, the idle slider assembly may comprise one or more idle rotating elements and said one or more first linear guide elements may comprise one or more linear rails, each one of said one or more idle rotating elements being configured to slide on a respective linear rail.

According to a further aspect of the invention, said one or more idle rotating elements may be selected from the group comprising idle wheels and idle rollers.

According to an additional aspect of the invention, the idle slider assembly may comprise one or more sliders and said one or more first linear guide elements may comprise one or more linear bars provided with bearings, each one of said one or more sliders being configured to slide on a respective bar or inside a respective bar.

According to another aspect of the invention, said one or more sliding elements may comprise one or more protruding elements of the plate operating as sliders each one of which is configured to slide inside a respective second linear guide element.

According to a further aspect of the invention, at least part of said one or more sliding elements may be provided with respective idle rotating elements and/or at least part of said one or more second linear guide elements may be provided with bearings.

According to an additional aspect of the invention, said idle rotating elements may be selected from the group comprising idle wheels and idle rollers.

According to another aspect of the invention, said through hole, having an internal thread, with which the plate is provided, may belong to a sleeve that is integrally coupled to the plate or that is an integral part of the plate. According to a further aspect of the invention, the coupling system may further comprise a motor to which the worm is coupled, whereby the worm is configured to be rotated by the motor.

According to an additional aspect of the invention, the coupling system may further comprise a server unit controlling the motor configured to receive a drive command from an external main controlling unit, so as to implement a servo control of the motor.

According to another aspect of the invention, the coupling system may further comprise manually operable gears configured to rotate the worm.

According to a further aspect of the invention, the tubular element may be configured to be coupled to at least one component of a safety apparatus in correspondence with an end of the same tubular element.

The advantages offered by the coupling system for safety apparatuses according to the invention with respect to prior art solutions are numerous and significant.

In fact, the coupling system according to the invention, permitting an accurate (optionally powered) positioning of at least one component of a safety apparatus, for instance an emitting device or a receiving device of one or more laser beams of a safety apparatus for press brakes, eliminating the rigid coupling of the safety apparatus component to the machine. This allows, in case of impact with an obstacle (such as an object or a person), the system components supporting the component to slide upwards even during the downward motion of the movable part of the machine, whereby the component discharges on the obstacle only its own weight and that of the coupling system components to which it is integrally coupled, which weight is usually low, ensuring the operator's safety even in such situation that instead, with the prior art coupling systems, is a hazardous situation.

The present invention will be now described, by way of illustration and not by way of limitation, according to its preferred embodiments, by particularly referring to the Figures of the annexed drawings, in which:

Figure 1 shows a schematic front view of a prior art coupling system that couples a device of a laser safety apparatus to a movable part of a press brake;

Figure 2 shows a schematic front view of the coupling system of Figure 1 in a hazardous situation;

Figure 3 shows a schematic front view of a preferred embodiment of the coupling system according to the invention that couples a device of a laser safety apparatus to a movable part of a press brake in a first configuration;

Figure 4 shows a schematic perspective view of the coupling system of Figure 3 in a second configuration;

Figure 5 shows a schematic top plan view of the coupling system of Figure 3; and Figure 6 shows a schematic front view of the coupling system of Figure 3 that, in a hazardous situation similar to that of Figure 2, ensures the protection of the operators.

In the Figures identical reference numerals will be used for alike elements.

It must be understood that the (relative) definitions of front, vertical, side and the like conventionally refer to an orientation of the point of view that is not essential and may be modified, still remaining within the scope of protection of the present invention as defined by the attached claims.

Furthermore, it must be understood that the coupling system for safety apparatuses according to the invention may be employed for coupling only one component of a safety apparatus to the mechanical working machine; for instance, in the case of a safety apparatus creating a laser optical barrier to apply to a press brake, the system may couple only the laser emitting device or only the laser receiving device of the safety apparatus to the movable part of the press brake.

With reference to Figures 3-5, it may be observed that a preferred embodiment of the coupling system according to the invention comprises a fixing bracket 206 having a first end 207 configured to be fixed to the movable part 2 of a press brake (or of another mechanical working machine) and a second end 208 provided with an idle slider assembly configured to slide along respective guide elements of the open side wall 213 of a tubular element 209, which open side wall 213 is configured to be facing the movable part 2 of the press brake; consequently, the fixing bracket 206 is configured to slide along the open side wall 213. The lower end 210 of the tubular element 209 is configured to be fixed to a device 1 of a laser safety apparatus (or to at least one component of a different safety apparatus), such as for instance a device for emitting or receiving one or more laser beams. The idle slider assembly comprises two pairs of idle wheels 214, the axes 215 of which are coupled to and protrude from the second end 208 of the fixing bracket 206, each pair of idle wheels 214 being configured to rotate along a respective vertical linear rail 216 (operating as guide element) with which the tubular element 209 is provided in correspondence with the open side wall 213; in particular, the two vertical linear rails 216 delimit the aperture of the open side wall 213 along the direction parallel to that along which the translational motion of the movable part 2 of the press brake occurs, i.e. along the vertical direction, and that is the direction along which the weight force of the assembly formed by the tubular element 209 (and of the components with which the latter is provided) and by the device 1 of the laser safety apparatus acts.

Other embodiments of the coupling system according to the invention may have idle slider devices and respective guide elements different from those shown in Figures 3-5; by way of example and not by way of limitation, at least some of the idle wheels 214 may be replaced with other idle rotating elements, such as idle rollers, and/or the number of the idle rotating elements (e.g. idle wheels or rollers) may be any number larger than two, i.e. three or more idle rotating elements (sliding along two or more rails, and the number of idle rotating elements per rail may be one or more, optionally up to sixteen, more optionally up to eight, still more optionally up to seven), and/or the rails may be more than two (i.e. three or more) whereby the side wall along which the idle slider assembly slides, instead of being completely open, is provided with grooves into which idle rotating elements configured to rotate along a respective vertical linear rail insert, and/or at least part of the idle rotating elements (e.g. idle wheels or rollers) and of the respective vertical linear rails may be replaced with sliders sliding on bars provided with bearings (operating as guide elements) or inside bars provided with bearings (also operating as guide elements) and/or at least part of the guide elements may be positioned on one or more side walls of the tubular element different from the side wall configured to be facing the movable part 2 of the press brake (for instance, the slider assembly could comprise shaped arms surrounding the tubular element and from which idle rotating elements protrude and insert into respective guide elements present on two or more of the side walls of the tubular element). Further embodiments of the coupling system according to the invention may have the tubular element configured to be coupled to at least one component of a safety apparatus in a different manner from what shown in Figures 3-5, for instance the component of the safety apparatus may be fixed, rather than to the lower end of the tubular element, to a different portion of this optionally through a bracket properly shaped to be adapted to this purpose.

Returning to make reference to the preferred embodiment of the coupling system according to the comprises invention shown in Figures 3-5, it may be observed that it further a worm 211 interacting with the internal thread of the through hole of a sleeve 217 of a plate 218 (in particular, the sleeve is not shown in Figure 4); in particular, the sleeve 217 may be integrally coupled to the plate 218 or it may be an integral part of the plate 218. The worm 211 is coupled to a motor 212 (that is not shown in Figure 4, where however the joint 219 between worm 211 and motor is shown) housed in the upper end of the tubular element 209, whereby the worm 211 is configured to be rotated by the motor 212.

Other embodiments of the coupling system according to the invention may have the motor 212 that is housed in any position inside or outside the tubular element 209. Further embodiments of the coupling system according to the invention may be devoid of the motor 212, and in this case rotation of the worm 211 may be operated by gears manually operable by an operator and/or such manually operable gears may be present in combination with the motor. Still other embodiments of the coupling system according to the invention may have a plate devoid of sleeve, whereby the worm 211 interacts with the internal thread of a through hole of the plate.

Returning to make reference to Figures 3-5, the plate 218 is configured so as to come out of the open side wall 213 of the tubular element 209 and to stably rest on the upper surface of the fixing bracket 206, as shown in Figure 3; the plate 218 is not integrally coupled to the (upper surface of the) bracket 206, as shown in Figure 5 wherein the coupling system is shown in a different configuration wherein the plate 218 is not resting on the upper surface of the fixing bracket 206. Also, the plate 218 is configured to slide within the tubular element 209; to this end, in the preferred embodiment of the coupling system according to the invention, the plate 218 comprises two protruding elements 220 operating as sliders sliding inside two vertical linear guides 221 within the tubular element 209.

Other embodiments of the coupling system according to the invention may have the plate provided with a different number of protruding elements operating as sliders sliding inside respective vertical linear guides within the tubular element 209, i.e. one or three or more protruding elements. Further embodiments of the coupling system according to the invention may have sliding elements different from the protruding elements 220 of Figures 3-5 configured to slide on respective linear guide elements different from the vertical linear guides 221 of Figures 3-5; for instance, at least part of the protruding elements of the plate may be provided with respective idle rotating elements, e.g. idle wheels or rollers, and/or at least part of the vertical linear guides within the tubular element 209 along which the protruding elements of the plate slide may be provided with bearings.

Returning to make reference to Figures 3-5, since the plate 218 is not integrally coupled to the (upper surface of the) bracket 206, the idle slider assembly of the fixing bracket 206 (comprising the two pairs of idle wheels 214 configured to rotate along respective vertical linear rails 216 of the tubular element 209) permits a reciprocal translational motion of the same fixing bracket 206 and the tubular element 209 to which the device 1 of the laser safety apparatus is fixed. However, the weight force of the assembly formed by the same plate 218, the tubular element 209 (and the components with which the latter is provided, such as the vertical linear rails 216, the vertical linear guides 221, the worm 211 and the motor 212) and the device 1 of the laser safety apparatus tends to cause the coupling system to assume the configuration shown in Figure 3, wherein the plate 218 is stably resting on the upper surface of the fixing bracket 206 (actually, the weight force of the same plate 218 and of tubular element 209, as well as of the components with which these are provided, is sufficient to make the coupling system assume the configuration shown in Figure 3).

When the motor 212 rotates the worm 211, the interaction of the latter with the internal thread of the through hole of the sleeve 217 of the plate 218 and the interaction of the protruding elements 220 with the respective vertical linear guides 221 make the same plate 218 slide along the worm 211. When the weight force of the assembly formed by the same plate 218, the tubular element 209 and the device 1 of the laser safety apparatus acts predominantly on the plate 218, this is stably resting on the upper surface of the fixing bracket 206 (as already stated, the weight force of the same plate 218 and of the tubular element 209, as well as of the components with which these are provided, is already sufficient to make the coupling system assume the configuration shown in Figure 3); in this case, when the motor 212 rotates the worm 211, this causes a vertical translational motion of the tubular element 209 with respect to the fixing bracket 206, represented in Figure 3 by bidirectional arrow A, and consequently a vertical translational motion of the device 1 with respect to the movable part 2 and punch 3 of the press brake, thus allowing an accurate positioning of the device 1 with respect to the (volume surrounding the) punch 3. Obviously, the direction of rotation of the worm 211 determines the direction of the vertical translational motion of the plate 218, and consequently of the tubular element 209, that may be upwards or downwards. Therefore, the tubular element 209 is configured to vertically translate with respect to the fixing bracket 206.

During the normal operation of the press brake, since the plate 218 is stably resting on the upper surface of the bracket 206, the coupling system shown in Figures 3-5, and hence the device 1, follows the translational motion of the movable part 2 of the press brake, represented in Figure 3 by bidirectional arrow B. However, since the plate 218 is not integrally coupled to the (upper surface of the) bracket 206, not even the tubular element 209 is integrally coupled to the movable part 2 of the press brake. Consequently, when a hazardous situation occurs, due to the fact that in the area below the device 1 of the laser safety apparatus is present an obstacle (such as an object or a person) with which the same device 1 comes into contact during the descent of the movable part 2 towards the fixed part 1 of the press brake, the assembly formed by the tubular element 209 and the device 1 remains resting on the obstacle in the impact zone, burdening the latter only with its own weight even when the movable part 2 continues its own translational motion towards the fixed part 4 of the press brake.

A similar hazardous situation is shown in Figure 6, wherein the bottom tool 5 is malpositioned on the fixed part 4 and the device 1 remains resting on the bottom tool 5 pushing on the latter only with the weight force of the assembly formed by the plate 218, the tubular element 209 and the device 1, even when the movable part 2 continues its own translational motion towards the fixed part 4 of the press brake. Moreover, in such situation, the optical barrier formed by the laser beams emitted by the safety apparatus is interrupted by the punch 3 of the same movable part 1, whereby the control electronic device of the laser safety apparatus connected to the control electronic unit of the press brake stops and prevents any further lowering of the movable part 2 of the press brake (when such stopping intervention by the control electronic device is provided by the operating configuration of the same laser safety apparatus).

In other words, when during a downward translational motion of the movable part 2 of the press brake, i.e. in a direction going from the plate 218 to the fixing bracket 206 (generally, in a direction along which a non-zero component of the weight force of the assembly formed by the plate 218, the tubular element 209 and the device 1 of the laser safety apparatus acts), the device 1 and, consequently, the tubular element 209 encounter an obstacle exerting a greater resistance than (said non-zero component) of the weight force of the assembly formed by the plate 218, the tubular element 209 and the device 1 of the safety apparatus, the device 1 and the tubular element 209 stop, resting on the obstacle. Differently, during an upward translational motion of the movable part 2 of the press brake, i.e. in a direction going from the fixing bracket 206 to the plate 218, the fixing bracket 206 drags the plate 218 and, consequently, the device 1 and the tubular element 209 upwards. In other words, the plate 218 and the tubular element 209 and, consequently, the device 1 are constrained to follow the translational motion of the fixing bracket 206 only in the direction going upwards, i.e. in the direction going from the fix ng bracket 206 to the plate 218.

Therefore, the coupling system according to the invention allows to avoid that the operator undergoes crushing or impacts directly or indirectly caused by the hit of a device of the laser safety apparatus (or of at least one component of a different safety apparatus) coupled to the movable part of the press brake (or of another mechanical working machine) with an obstacle that were present below the same. In this regard, it is important to point out that the weight of the assembly formed by the tubular element 209 and the device 1 that would burden on the obstacle in correspondence with the impact zone is low and is not capable to cause significant impacts and/or overturning, in particular any overturning of heavy objects such as the bottom tool 5 of the press brake (as shown in Figure 6) or damages to the operator even if the latter directly came into contact with the device 1, because the latter would stop its own downward run as soon as it would come into contact with the obstacle (possibly with the same operator).

Other embodiments of the coupling system according to the invention, provided with a motor 212 configured to rotate the worm 211, may further have a server (or slave) unit controlling the motor 212 configured to receive a drive command from a main (or master) unit controlling a motor of an external coupling system (optionally another coupling system according to the invention), so as to implement a servo control of the motor 212 configured to position the plate 218 so that the device 1 fixed to the tubular element 209 is at the same height at which the external coupling system couples another device of the safety apparatus to the movable part 2 of the press brake (in the case where the external coupling system is another coupling system according to the invention, such servo control of the motor 212 is configured to position the plate 218 at the same height at which the external coupling system positions its own plate).

The preferred embodiments of this invention have been described and a number of variations have been suggested hereinbefore, but it should be understood that those skilled in the art can make other variations and changes without so departing from the scope of protection thereof, as defined by the attached claims.