Method for removing at least one clamped part, associated clamping system and loading method - Patents.com

Abstract

The detachment method is carried out using a magnetic clamping system comprising a detection device having a transmitter of an electromagnetic signal (SI) controlled according to a force (F) and an electromagnetic signal receiver, the electromagnetic signal receiver outputting an output signal (S104) having a first value (V1) when the receiver receives an electromagnetic signal and outputting a second value otherwise. The method further comprises the steps of determining (2078) the force (F) between the carriage and the hook, and comparing the force (F) with a threshold value (F 0 ) (2080). If the force is greater than the threshold, the transmitter is activated (2084). Meanwhile, the receiver output signal (S104) is collected (2062) and the value contained in the output signal (S104) is determined (2086). If it is the first value (V1), the input of the command to degauss the magnetic pad is authorized (1012). If not, the input of the command to degauss the pad is prevented (2088).

Description

[Technical field]

[0001] The present invention relates to a method for unloading at least one part clamped on a magnetic clamping system of an industrial installation using a hoist. The present invention further relates to a magnetic clamping system configured for implementing such a method. Finally, the present invention relates to a method for loading at least one part clamped on such a magnetic clamping system using a hoist.

[0002] The present invention relates to a magnetic clamping system, e.g. dedicated to plastics processing operations, and to a method of operating same, and in particular to improving the quick mould change procedure of an injection moulding machine, more specifically to limit the risk of the mould falling when it is removed using a lifting device such as a hoist.

[0003] In the field of rapid mold changeovers in injection molding machines, it is known to use mechanical clamping systems to secure each mold section to the fixed and moving sections of the press. This can be tedious, and it is desirable to make this less taxing for the operator when heavy and dangerous loads are present, and in difficult industrial environments in terms of space, heat, and chemical vapors. The design of magnetic clamping systems has led those in the industry to develop procedures to automate, in order to reduce the number of times both sections of the mold are manipulated between the plastic molding phases, making the operation safer.

[0004] The operator uses a lifting device, usually a type of hoist, mounted above the press to transport the molds according to the cycles required for the production of the various plastic parts.

[0005] During the operating phase, it is necessary to take into account the states of two different environments, namely the press installation and the lifting device, which do not normally communicate with each other. In particular, during the operation of removing the mould in an injection moulding machine, while the demagnetisation of the mould of the clamping plates is started, the lifting device is not able to hold the mould or is not yet able to hold it, and therefore there is a risk that it will fall off the installation.

[0006] The activation and deactivation of the electromagnets of the magnetic clamping system has so far been conditioned by the state of the injection molding machine, but not by the state of the lifting device. The hoist is not designed to transmit status information to the magnetic clamping system or to communicate any load data. Furthermore, the lifting device has a displacement mark and the press has its own displacement mark. The distance between the lifting device and the press can be large, in the order of 5, 10 or 20 meters. However, the operation of removing the mold between the press and the lifting means requires a fairly accurate positioning of said hoist above the mold to be removed in order to prevent the mold from swinging in the installation.

[0007] It should be noted that since lifting devices such as hoists have their own computer language and follow specific communication standards, the plastic processing equipment has little tendency to communicate with the lifting devices in a network and control their operation. For equipment and personnel safety, it is highly preferable that the position, speed or otherwise of the lifting devices be controlled by an operator who knows the workplace environment and is competent for such operation, without the press sending information back to the hoist contrary to the intended operation which could be the source of a fall or accident.

[0008] It is known from US Pat. No. 5,399,633 to add to the magnetic pads of the magnetic clamping system an additional coil connected in series with a measuring circuit connected to a control unit in order to measure the magnetic flux in the pad installation and to monitor the movement of the mould and prevent it from falling. Overall, such a solution is satisfactory. However, it does not address the problem of safely demagnetising the mould when it is being transported by the lifting device.

[0009] On the other hand, US Pat. No. 5,999,633 discloses a lifting device with a test unit. Such a lifting device has a load sensor to check that the deployed lifting magnetic force corresponds to the weight of the part to be lifted. Such technology does not address the issue of demagnetizing a mold that needs to be unclamped in order to be removed from the press.

[0010] Thereby, in known installations the following accident conditions cannot be excluded: - The hoist was positioned above the equipment, but the hook was not engaged with the mould due to an operating error, creating a risk of the mould falling during degaussing. The mould was coupled to a hoist, but due to an operating error the hoist was not positioned correctly, presenting a risk of the mould tipping over or becoming unlocked during degaussing.

[0011] Similar problems arise in other types of installations with machines, parts of which, such as machining centers, for example, must be changed during the service life of the machine. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] European Patent Application Publication No. 1867437 [Patent Document 2] International Publication No. 2008 / 142716 Summary of the Invention

[0013] More specifically, it is these drawbacks that the present invention seeks to overcome by proposing a new method of removing at least one part clamped on a magnetic clamping system, using a hoist, which is more reliable than the methods of the prior art and makes it possible to prevent dangerous situations to a greater extent.

[0014] For this purpose, the invention relates to a method for removing at least one part clamped on a magnetic clamping system of an industrial plant by means of a hoist, the hoist comprising: a carriage movable within a horizontal plane; a hook suspended from the carriage and vertically movable; a hook load detection device configured to determine a force between the carriage and the hook; a hoist control unit. The magnetic clamp system is - a magnetic clamp control unit; at least one magnetic clamping plate including a plurality of selectively magnetizable magnetic pads controlled by a magnetic clamping control unit; a human machine interface, which is connected to the magnet clamp control unit and allows commands for demagnetizing the magnetic pads to be entered. According to the present invention, The magnetic clamping system includes a device for detecting a position of the carriage relative to the clamping plate, the detection device comprising: a transmitter of an electromagnetic signal, fixed to the carriage and controlled according to a force determined by a hook load detection device; a receiver for the electromagnetic signal emitted by the transmitter, the receiver being fixed relative to the clamping plate and configured to provide an output signal, the output signal comprising a first value when the receiver receives an electromagnetic signal and a second value when the receiver does not receive an electromagnetic signal; The method of removal is (a) determining a force between a carriage and a hook using a hook load detection device; (b) comparing the force determined in step (a) to a threshold; (c) activating the transmitter if the comparison performed in step (b) indicates that the force determined in step (a) is greater than a threshold value; and (d) during step (c), acquiring an output signal from the receiver; (e) determining which of the first and second values ​​is present in the receiver output signal; (f) authorizing input of a command to demagnetize the magnetic pad by the human machine interface if the determination in step (e) indicates that the output signal collected in step (d) includes a first value; (g) preventing input of a command to degauss the magnetic pad by the human machine interface if the determination in step (e) indicates that the output signal collected in step (d) includes a second value; and The method includes at least the steps of:

[0015] According to the invention, the method of removal can lead to an effective demagnetization of the magnetic pads of the clamping system only when the receiver output signal confirms that the hoist hook is actually under load and that the hoist carriage is correctly positioned relative to the clamping plate. The risk of untimely demagnetization of the magnetic pads of the clamping plate is thereby minimized.

[0016] According to advantageous but non-essential aspects of the invention, such a method may incorporate one or more of the following features, adopted according to any technically possible combination: - Step (g) is maintained as long as the signal collected in step (d) has a second value. - the receiver delivers an output signal having a first value when the transmitter is activated and is in a predetermined position relative to the receiver, and the receiver delivers an output signal having a second value when the transmitter is not operating and / or is not in a predetermined position relative to the second element. The predetermined position of the transmitter is opposite to the receiver. The predetermined position of the transmitter corresponds to the vertical alignment of the carriage with the part clamped on the magnetic clamping system. the electromagnetic signal emitted by the transmitter comprises an identification frame intended to be collected by the receiver, the method comprising an additional step (h) of making a comparison between the identification frame collected by the receiver and a reference identification frame, and if the result of the comparison in step (h) is negative, the input of a command to demagnetize the magnetic pad is prevented regardless of the value determined in step (e). may incorporate one or more of the following: The method of removal is (i) prior to step (c), determining whether the receiver is in an operational state; (j) if step (i) determines that the receiver is operational, proceeding to step (e); (k) if it is determined in step (i) that the receiver is not in working condition, switching to a manual mode, in which an operator must confirm at least one step by answering questions via a control terminal connected to the magnetic clamp control unit; The method includes the additional step of:

[0017] According to another aspect, the present invention provides a magnetic clamping system including a magnetic clamp control unit and at least one magnetic clamp plate including a plurality of selectively magnetizable magnetic pads controlled by the magnetic clamp control unit, the magnetic clamping system comprising: The magnetic clamping system comprises a device for detecting the position of the carriage of the lifting device relative to the magnetic clamping plate, the detection device comprising: a transmitter of an electromagnetic signal, fixed to the carriage; a receiver of the electromagnetic signal emitted by the transmitter, the receiver being fixed relative to the clamping plate and configured to output an output signal comprising a first value when the receiver receives an electromagnetic signal and a second value when the receiver does not receive an electromagnetic signal, The clamping system is configured to perform at least steps (c) to (g) of the method described above. The present invention relates to a magnet clamp system.

[0018] The system of the present invention aids in efficiently implementing the method of the present invention.

[0019] According to advantageous but non-essential aspects of the invention, such a system may incorporate one or more of the following features, adopted according to any technically possible combination: The electromagnetic signal is an infrared signal and the receiver is configured to detect the infrared signal. The electromagnetic signal is emitted by a laser diode or a light emitting diode, and the receiver is configured to detect the laser signal or the light emitting signal. The receiver is oriented along a vertical axis, while the reception zone of the receiver is in the shape of a cone or a frustum of a cone centered on the vertical axis. The receiver is oriented along a horizontal axis, while the reception zone of the receiver is in the shape of a cone or a frustum of a cone centered on the horizontal axis. the receiver comprises a microcontroller liable to communicate the first value or the second value contained in the output signal to a magnetic clamp control unit; The receiver is configured to transmit the presence information to the magnet clamp control unit. may incorporate one or more of the following:

[0020] According to a third aspect, the present invention relates to a method for loading at least one part to be clamped into a magnetic clamping system of an industrial installation using a hoist, the hoist comprising: a carriage movable within a horizontal plane; a hook suspended from the carriage and vertically movable; a hook load detection device configured to determine a force between the carriage and the hook; and a hoist control unit. According to the present invention, - the magnetic clamping system is as described above, the hook load detection device is configured to determine a mass of a workpiece to be clamped based on a force between the carriage and the hook; the electromagnetic signal emitted by the transmitter comprises information about the mass of the part to be clamped, which is determined by a hook load detection device; the receiver is configured to extract information of the mass of the part to be clamped from the electromagnetic signal received from the transmitter and to communicate it to a magnet clamp control unit of the magnet clamping system, the removal method is carried out by a magnetic clamping system; and (l) comparing the information about the mass of the part to be clamped extracted from the electromagnetic signal with a predetermined threshold value; (m) preventing loading or issuing an alarm if the comparison in step (l) indicates that the mass of the part to be clamped is greater than a threshold value; (n) authorizing loading if the comparison in step (l) indicates that the mass of the part to be clamped is less than the threshold value; The method includes at least the steps of:

[0021] Other aspects of the invention will be better understood and the invention will appear more clearly in the light of the following description of a detachment method, a clamping system, and three embodiments of a detachment method according to its principles, given by way of example only, and by making reference to the accompanying drawings, in which: [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic representation of the principle of an installation of an injection molding machine incorporating a clamping system according to the invention, which is adapted to implement the method according to the invention. [Diagram 2] FIG. 2 shows, in two illustrations (A) and (B), a particular part of the installation of FIG. 1 during two steps of the removal method according to the invention. [Diagram 3] FIG. 3 shows in two illustrations (C) and (D) the same part of the installation as in FIG. 2, during two other possible steps of the removal method. [Figure 4] FIG. 4 shows in two illustrations (E) and (F) the same part of the installation as in FIGS. 2 and 3, during two other steps of the removal method. [Diagram 5] FIG. 5 is a block diagram of a detachment method according to the present invention, implemented using the equipment shown in FIGS. [Figure 6] FIG. 6 is a view similar to FIG. 1 of an installation incorporating a clamping system according to a second embodiment of the invention and adapted to implement the method according to the invention. [Figure 7]FIG. 7 is a view similar to FIG. 1 of an installation including a clamping system according to a third embodiment of the invention and configured to implement the method according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The plastic processing installation 2 shown in Figure 1 is part of a plant for converting synthetic materials into moulded parts. This installation comprises one or more production lines, each formed by one or more injection moulding machines, only one of which is indicated in the figure by reference number 4. The injection moulding machine 4 comprises a fixed mould mount 6 and a movable mould platen 8 movable parallel to the X-axis of a fixed Cartesian coordinate system XYZ, which are guided parallel to said axis by rails 10. The X-axis is horizontal, the Y-axis is also horizontal and perpendicular to the X-axis, and the Z-axis is vertical and therefore perpendicular to the X-axis and the Y-axis.

[0024] A mold 12 mounted on the injection molding machine 4 includes two portions 12A and 12B made from a ferromagnetic material and secured to the fixed mold mount 6 and the moveable mold platen 8, respectively.

[0025] Thereby, the movement of the movable mold platen 8 parallel to the X-axis serves to ensure the opening and closing functionality of the mold 12 during the production of molded parts.

[0026] The injection molding machine 4 further comprises a control unit 14 comprising, in particular, a calculator 16 enabling the injection molding machine 4 to be controlled according to a pre-determined sequence stored in a memory 18.

[0027] The two parts 12A and 12B of the mold 12 are fixed to the fixed mold mount 6 and the movable mold platen 8, respectively, by a magnetic clamping system 20 that includes a number of magnetic pads 24. The magnetic pads 24 are selectively magnetizable in the sense that they can be selectively magnetized or demagnetized, i.e., they can be controllable to switch between a configuration in which the pads are magnetized and a configuration in which the pads are not magnetized, and vice versa. The magnetic pads 24 are distributed across a first clamping plate 26, which is fixed by mechanical means on the fixed mold mount 6, and a second clamping plate 28, which is fixed by other mechanical means on the movable mold platen 8.

[0028] The mechanical means for securing the clamping plates 26 and 28 onto the fixed mount 6 and the movable platen 8 are preferably screws.

[0029] In FIG. 1, only the magnetic pads 24 of the clamping plate 26 that are not covered by the mold portion 12B can be seen.

[0030] Advantageously, the magnetic pads are of the type described in EP 1 867 437 A1. The invention is also suitable for the clamping plate technique, in which the magnetic pads are each identified by a north or south pole and are associated with a magnetic plate for clamping the mould. The invention is also suitable for the monolithic magnetic clamping plate technique, in which the magnetic pads are each identified by a north or south pole and are associated with a magnetic plate for clamping the mould. The invention is also suitable for the monolithic magnetic clamping plate technique, in which the magnetic pads are each identified by a north or south pole and are associated with a magnetic plate for clamping the mould.

[0031] The magnetic pads 24 are controlled by a magnetic clamp control unit 34. The magnetic clamp control unit 34 also belongs to the magnetic clamp system 20 and comprises a computer 36 and a memory 38 associated with the computer 36. The computer 36 controls each of the magnetic pads 24 through control power cables connecting the magnetic clamp control unit 34 to the clamp plates 26 and 28, only one of which can be seen in Figure 1 and is referenced C20.

[0032] According to convention, the mold part 12A or 12B is considered to be attached against the front face of the clamping plate 26 or 28, which thus forms the clamping face of the plate on which the plate appears supported by the magnetic pads 24. Each clamping plate 26 or 28 is provided at its rear face, opposite its front clamping face, with a housing (not shown) for receiving connection means 262 and 282 intended to electrically connect the various magnetic pads 24 to each other and to a terminal block (not shown) for connecting the various magnetic pads 24 to the magnetic clamp control unit 34 via the control cable C20 and its equivalents (cables). Grooves provided at the rear face of each clamping plate 26 or 28 serve for routing the wires and for positioning the particular connection means 262 and 282.

[0033] The magnetic clamping system 20 further comprises a control terminal 40 operated by an operator, which further interacts with the clamp control unit 34 via a wired connection, represented in FIG. 1 by cable C40, or in one variant through a wireless link.

[0034] The function of the magnetic clamp control unit 34 is, inter alia, to switch the poles of the magnetic pads 24 fixed to the clamping plates 26 and 28. This is done according to the instructions of a program stored in a memory 38 and executed by a computer 36, or according to instructions received from a control terminal 40, which allows an operator to intervene and initiate, cancel or activate the control of the magnetic pads 24.

[0035] The control terminal 40 allows in particular to hold the parts 12A and 12B fixed to the clamping plates 26 and 28 or to release the parts 12A and 12B from the clamping plates 26 and 28 by giving the operator the possibility to remotely magnetize or demagnetize the magnetic pads 24 of the clamping plates 26 and 28 by means of the control terminal. The control terminal 40 forms a human machine interface. In a variant, the input of the demagnetization command may be performed by means of a physical button connected to the control unit, which in such an example forms the human machine interface. Alternatively, the input of the demagnetization command may be performed by means of another form of human machine interface.

[0036] When the magnetic pads 24 are magnetized, the clamp control unit 34, in response to commands received from the computer 36 or terminal 40, controls the magnetic clamping force exerted by each clamp plate 26 or 28 on the corresponding mold portion 12A or 12B.

[0037] Furthermore, the magnetic clamping control unit 34 is connected to different sensors (not shown) which are integrated into the magnetic clamping system 20 and may include temperature sensors, mold presence sensors, etc.

[0038] The magnetic clamping system 20 is supplied with electrical current through the injection molding machine 4 .

[0039] The mold 12, in turn, is provided with a locking mechanism 42 formed by a first portion 42A attached to the portion 12A of the mold 12 and a second portion 42B attached to the portion 12B of the same mold. The portions 42A and 42B are designed to cooperate when the locking mechanism 42 is activated to secure the two portions 12A and 12B of the mold together.

[0040] As can be seen in FIG. 1, where two portions 42B are disposed on either side of mold portion 12B, locking mechanisms 42 are advantageously provided on each of the two vertically oriented side portions of the two mold portions.

[0041] When the mold 12 is not placed in the injection molding machine 4, the mold 12 is in a configuration in which its locking mechanism 42 is activated, i.e. in a position in which the two mold parts 12A and 12B are pressed and fixed against each other by the mechanism.

[0042] Mold 12 also includes lifting eyebolts 44, which in this example are attached to the top surface of mold portion 12B, whereby when locking mechanism or locking mechanism 42 is activated, lifting eyebolts 44 serve to lift the entire mold 12.

[0043] The installation 2 further comprises a lifting device 50 which serves to move the mould 12 spatially along the three directions of a Cartesian coordinate system XYZ.

[0044] The lifting device 50 comprises a carriage 52 slidably mounted on two rails 54 parallel to the X-axis, whereby the carriage 52 is movable in a horizontal plane parallel to the X-axis and the Y-axis.

[0045] Preferably, when several injection moulding machines 4 form part of the plastics processing installation 2, they are aligned parallel to the X-axis with their injection faces parallel or perpendicular to said axis, so that the different injection moulding machines can access the same lifting device 50.

[0046] According to one variant of the invention, the rails 54 can be mounted to slide on beams (not shown) that run parallel to the Y axis and are fixed relative to the structure of the building containing the plastic processing installation 2. This is only shown for the third embodiment.

[0047] The lifting device 50 further comprises a hoist 56, which is attached to the carriage 52 and comprises a cable 58 supporting a pulley block 60. The winding of the hoist 56 on the drum 62 is controlled by an electric motor 64. A hook 66 is suspended from the pulley block 60 and forms part of the hoist 56. The hook is vertically movable below the carriage 52 by the winding of the cable 58 on the drum 62. The hook 66 is designed to interact with the lifting eyebolt 44 when it is required to lift the mould 12 relative to the parts 6 and 8 of the injection moulding machine 4.

[0048] The lifting device 50 further comprises a hook load detection device, which comprises a sensor 68 for the load of the hoist. Advantageously, the hook load detection device comprises means (not shown) for processing the output signal of the sensor 68 for the load of the hoist. The load of the hoist corresponds to the tension of the cable 58. The sensor 68 is able to detect said tension and to transmit a corresponding signal via a wired link 72 to a control unit 74. The control unit 74 comprises notably a calculator 76 enabling the control of the lifting device 50, and a memory 78. The wired link 72 also serves to supply power to the motor 64.

[0049] In one variation, the output signal from the sensor 68 is provided to the control unit 74 via a wireless link.

[0050] A control unit 74 is provided to control the movement of carriage 52 along rails 54 and the rotation of cable 58 on drum 62, and to monitor force F, which is exerted between carriage 52 and hook 66, and which depends on the weight of the elements suspended from carriage 52, and more specifically, the weight of pulley block 60, hook 66, and mold 12 when mold 12 is suspended from hoist 56 by lifting eye bolts 44.

[0051] In practice, the force F monitored by the control unit 74 is the force detected by the sensor 68 and corresponds to the pulling force on the strands of the cable 68 extending between the pulley block 60 and the drum 62. This pulling force opposes the magnetic force holding the mold 12 on the clamp plate 26.

[0052] The control unit 74 may also include one or more power circuits (not shown) that serve to power the electric motor 64 via the wired connection 72 .

[0053] The lifting device 50 further comprises a control terminal 80 intended to be operated by an operator. The control terminal 80 interacts with the control unit 74 via a wired connection, represented in Fig. 1 by a cable C80, or in one variant through a wireless link.

[0054] The magnetic clamping system 20 further comprises a device 100 for detecting the position of the carriage relative to the clamping plate 26. The position detection device 100 comprises an infrared transmitter 102 fixed to the carriage 52 and an infrared receiver 104 fixed to the frame 6 and thus relative to the clamping plate 26 fixed on said frame.

[0055] In the illustrated example, the transmitter 102 is suspended from the carriage 52 by a rod 106, while the receiver 104 is attached to a mast 108 which is fixed on the fixed mount 6.

[0056] In one variant, as shown in FIGS. 2-4, the transmitter 102 is integrated into the carriage 52 while the receiver 104 is integrated into the fixed mount 6.

[0057] Here, the transmitter 102 is fixed in the coordinate system of the carriage 52, while the receiver 104 is fixed in the coordinate system of the clamp plate 26, i.e. in a fixed Cartesian coordinate system XYZ.

[0058] The receiver 104 is oriented along a vertical axis, parallel to the Z-axis, and is configured to detect an infrared signal SI emitted by the transmitter 102 when the transmitter 102 is actuated and located above the receiver 104 within a receiving cone K104 defined by the receiver 104 and centered on the vertical axis. The receiver 104 comprises a detection zone configured to detect the infrared signal SI.

[0059] The receiving cone K104 provides a certain tolerance for the position of the detection device 100, since the receiver 104 can detect the infrared signal SI emitted by the transmitter 102 over an acceptable disk-shaped range at the top of the cone K104, extending in the XY plane of the coordinate system XYZ.

[0060] To provide efficient and smooth lifting of the mold 12 relative to the injection molding machine 4, the hook 66 should be accurately positioned relative to the lifting eyebolt 44 before the mold 12 is unclamped and lifted by the hoist 56 with an upwardly directed pulling force. However, the position of the lifting eyebolt 44 in the Cartesian coordinate system XYZ varies according to the thickness E of the mold 12, which corresponds to the distance between the front faces of the clamp plates 26 and 28 measured parallel to the X-axis. The transmitter 102 is fixed relative to the carriage 52, and the receiver 104 is fixed relative to the fixed mold mount 6 in a position such that the vertical alignment of the hook 66 on the lifting eyebolt 44 corresponds to a predetermined position of the transmitter 102 relative to the receiver 104.

[0061] Advantageously, in such an embodiment, this predetermined position is one in which the transmitter 102 faces the receiver, in the present example being vertically aligned with the receiver 104 .

[0062] When the transmitter 102 is in the predetermined position, the carriage 52 is vertically aligned with the mold 12 clamped to the injection molding machine 4 .

[0063] In the first embodiment shown in FIGS. 2-4, the direction of the infrared signal SI emitted by the transmitter 102 is parallel to the Z axis and directed downward.

[0064] Advantageously, the direction of emission of the infrared signal SI is selected so that said signal cooperates with the receiver 104 only when the carriage 52 is in a position that corresponds to a predetermined position of the transmitter relative to the receiver 104.

[0065] d102 refers to the distance measured parallel to the X-axis between the geometric center of the pulley block 60 and the point of emission of the infrared signal SI by the transmitter 102. d104 refers to the distance measured parallel to the X-axis between the geometric center of the receiving zone of the receiver 104 and the geometric center of the lifting eyebolt 44. The distances d102 and d104 are selected according to the geometry of the injection molding machine 4 and the carriage 52. The distances d102 and d104 correspond to each other such that, at a predetermined position of the transmitter 102 relative to the receiver 104, the hook 66 is vertically aligned with the lifting eyebolt 44.

[0066] The receiver 104 comprises a microcontroller (not shown) configured to communicate its status to the magnet clamp control unit 34 in the form of an electronic signal S104, which is transmitted via an electrical cable C104 or, in one embodiment, via a wireless link. The signal S104 contains status information of the receiver 104, which has a first value V1 when the receiver 104 receives an infrared signal S1 transmitted by the transmitter 102, and a second value V2 when the receiver 104 is not receiving the infrared signal.

[0067] For example, the first value V1 may be a positive value and the second value V2 may be a negative value.

[0068] When the transmitter 102 is in a predetermined position relative to the receiver 104 but is not operational, i.e., not emitting an infrared signal SI, the receiver does not detect the signal and its output signal includes a second value V2.

[0069] Advantageously, the receiver 104 is arranged to transmit presence information to the magnetic clamp control unit 34, which allows the receiver 104 to be tested by the control unit periodically or as required. For example, it may be provided that the receiver 104 periodically transmits an output signal S104 with a second value V2 to the clamp control unit 34, which output signal S104 serves to ensure that the receiver is in place, connected and operational, regardless of the position and activation of the transmitter 102. The reception by the receiver 104 of the first value V1 or the second value V2 of the signal S104 is assimilated to the reception of presence information from the receiver 104. Furthermore, if the receiver 104 is detected as being in place, connected and operational, the analysis of the receiver's status based on the two possible values ​​of the output signal 104 may be used to authorize or prohibit in a safe manner the demagnetization of the magnetic pad 24. This will be explained below.

[0070] The method of removing the mold 12 using the hoist 56 will now be described with reference to Figures 2-5.

[0071] At the end of the injection cycle, it may be necessary to change the mold 12 to make a new type of part or for maintenance of the mold 12 or the injection molding machine 4. The challenge is to safely remove the mold 12, which is a very heavy steel assembly, from the injection molding machine 4.

[0072] The safe removal is based in particular on synchronizing the lifting movement of the mold 12 using the hoist 56 with the demagnetization of the magnetic pads 24. In particular, it is based on tensioning the cables 58 in a direction perpendicular to the mold 12 before the demagnetization of the magnetic pads 24.

[0073] The removal method begins at step 1000 when the mold 12 is held in place in the injection molding machine 4 by the magnetized magnetic pads 24. During step 1000, the hoist 56 is unloaded, i.e., available, and the cable 58 is wrapped for the most part around the drum 62, so that the hook 66 is in the up position. This step is shown in insert (A) of FIG.

[0074] During a step 1002, the magnetic clamp control unit 34 checks whether the receiver 104 is in operation.

[0075] If not, the method switches to manual mode and performs step 1004. During step 1004, the operator is asked by a human machine interface, which may be an interface formed by the control terminal 40, to determine whether the locking mechanism 42 is in a locked configuration in which the mold parts 12A and 12B are fixed relative to each other. The operator can reply to this question on said interface after visually checking the locking mechanism 42. If the operator replies no or does not reply within a predefined time Δt, for example 5 seconds, the method returns to step 1000. If the operator verifies in step 1004 that the locking mechanism 42 is in an actuated state, the method proceeds to step 1006. In step 1006, the operator is requested to manually check that the hoist 56 is correctly positioned and that the hook 66 is engaged with the lifting eyebolt 44. The operator can reply to this question via a human machine interface, which may be formed by the control terminal 40, after visually checking the lifting device 50. If the operator replies no, or fails to reply within a predetermined time Δt, such as 5 seconds, the method returns to step 1000. If the operator confirms that the hoist is properly attached, the method moves to step 1008 through "OR" logic gate 1010.

[0076] During a step 1008, in order to release the mold 12, the operator is asked, via an input interface of the magnetic clamp control unit 34, which may be integrated in the terminal 40, to know whether he / she approves the demagnetization of the magnetic pads 24. If the operator does not reply within a time corresponding to a time Δt, such as 5 seconds, the method automatically returns to step 1000.

[0077] If the operator accepts the demagnetization command via the input interface, demagnetization of the magnetic pads 24 occurs during step 1012. The operator is informed thereof by a corresponding message displayed on the human machine interface of the control terminal 40 during step 1014. The magnetic pads of the two clamping plates of the clamping system are simultaneously demagnetized in step 1012.

[0078] After the above demagnetization, during a step 1016 the injection molding machine is opened by moving the movable mold platen 8 away from the fixed mold frame 6 according to a translational movement parallel to the X-axis.

[0079] Thereafter, during step 1018, the mold is released and, during step 1020, which is the end of the removal method of the present invention, the operator proceeds to lift and transport the mold 12 using the hoist 56 by controlling the lifting device 50 by means of the terminal 80.

[0080] After step 1020, operations to change mold 12 continue according to known transfer procedures.

[0081] Steps 1004 and 1006 correspond to a manual implementation of the removal method, during which the operator checks the status of the equipment 2 himself and commands the demagnetization of the magnetic pad 24 after verifying, within a given time, using the terminal 40, that certain conditions are met by the locking mechanism 42 and the hoist 56.

[0082] Except where operator action is required, as described with reference to steps 1004, 1006, and 1008, the above steps 1000, 1002, and 1012-1018 are performed automatically by clamp control unit 34, and by control units 14 and 74 and terminal 80.

[0083] On the one hand, the removal method is performed after a previous transfer operation has been performed during step 2000, and the end of the preceding transfer occurs during step 2010. This allows the hoist 56 to be brought into a configuration in which it is available, i.e., unloaded, which occurs in step 2020.

[0084] Following step 2020, the operator communicates via the terminal 80 to the control unit 74 a command to position the carriage 52 along the X-axis, which is performed during step 2030. This leads to a movement of the hoist 56, which is performed during step 2040 and brings the carriage into the position generally shown in the illustration (B) of FIG. 2, in which the transmitter 102 is vertically aligned with and above the receiver 104. More specifically, the transmitter 102 is now located within the receiving cone K104 of the receiver 104. During step 2050, the operator visually checks whether the carriage 52 is positioned along the X-axis so that the hoist 56 is above the mold 12, more specifically so that the hook 56 is generally vertically aligned with the lifting eyebolt 44.

[0085] If not, movement of the hoist is resumed by the operator by returning to step 2040. If true, the method transitions through "AND" logic gate 2060 to step 2062.

[0086] In step 2030, following and in parallel with step 2020, the operator communicates to the control unit 74 via the terminal 80 a command to lower the hook 66, which occurs during step 2070, which induces the lowering of the hook 66, which occurs during step 2072, and further induces the locking of the hook to the lifting eyebolt 44, which occurs during step 2074, with the assistance of the operator if necessary, as shown in insert (C) of FIG.

[0087] In such a position, the transmitter 102 is disposed inside a receiving cone K 104 defined by the receiver 104 .

[0088] During the next step 2076, the motor 64 is actuated so as to wind a portion of the cable 58 onto the drum 62, as indicated by the arrow A1 in the inset (E) of Figure 4. This has the effect of placing the hook 66 under load, i.e. under tension, by exerting between the carriage 52 and the hook 66 a tension F in the cable 58 which corresponds to the load on the hook.

[0089] During a subsequent step 2078, the hook load resulting from step 2076 is determined by the hook load detection device which determines a force F from the load information of the sensor 68.

[0090] This force F determined in step 2078 is compared with a threshold reference force F0 during a subsequent step 2080. Step 2078 is preferably performed by the control unit 74 of the lifting device 50.

[0091] In one variation, step 2078 is performed in a computer of the hook load detection device, which is embedded in the hoist 56 and connected to the processing means of the hook load detection device.

[0092] If the force F detected in step 2078 is strictly less than the threshold value, step 2082 is performed. In step 2082, the transmitter 102 is deactivated, i.e. stops transmitting the infrared signal SI. In such an example, the control unit 74 sends a signal to the transmitter 102 to switch it off, i.e. to stop emitting the infrared signal SI. Such an example corresponds to the fact that step 2078 is performed periodically, even after the transmitter 102 has started the operation following step 2084 mentioned below. It serves to react to a decrease in the value of the force F during the detachment method. After step 2082, the method automatically returns to steps 2072, 2074 and 2076.

[0093] If the force F detected in step 2078 is greater than or equal to the threshold value F0, the method proceeds to step 2084 of activating the transmitter 102, i.e. sending a command to the power supply transmitter to operate it, in other words emitting an infrared signal IF. The transmitter 102 starts to operate by powering the emitter. The emission of the infrared signal SI is thereby controlled by the load detection device according to the force F determined in step 2078. If the emission of the infrared signal SI does not occur within a time shorter than a pre-determined time, which may be equal to 500 milliseconds, the method returns to step 2080. If the emission of the infrared signal occurs during step 2084, the method proceeds to step 2062 through the logic gate 2060.

[0094] The "AND" logic gate 2060 thereby makes it possible to simultaneously check whether the carriage 52 is in a determined position and whether the transmitter 102 is emitting a signal SI.

[0095] In step 2078, the sensor 68, which is the load sensor of the hoist 56, detects an increase in the load on the hook.

[0096] The hook load detection device 68 comprises a calculator (not shown) for carrying out step 2080 and a memory (also not shown) for storing a threshold value F0, for example equal to 500 daN, which was previously entered during calibration of the installation 2. If, during step 2080, the detected force F exceeds the threshold value F0, the calculator considers that an actual hook load is present, i.e. that a loaded condition of the hoist 56 exists, and causes the transmitter to send a feed command, which causes an infrared signal to be emitted during step 2084. Corresponding information can be transmitted to the terminal 80, informing the operator of the loaded condition of the hoist.

[0097] In one variant, the load detection device 68 of the hoist 56 transmits information about the actual load to the position detection device 100 of the carriage 52. The position detection device 100 includes a calculator and a memory that includes a threshold value F0. The detection device 100 then performs a step 2080 in which it makes a comparison between the detected force F and the threshold value F0 and activates the infrared transmitter 102 if the force value F exceeds the threshold value F0 or does not switch on the infrared transmitter if the force value F does not exceed the threshold value F0.

[0098] Whatever the mode of obtaining information about the hook load and the way in which the comparison of step 2080 is implemented, the transmitter receives binary information that corresponds to the result of the comparison of step 2080 and that may or may not enable the transmitter to initiate an action.

[0099] Thus, the detachment method comprises preliminary steps 2000 to 2080, on which the activation of the transmitter 102 depends and which in particular comprise, during a step 2078, the determination of the force F between the carriage 52 and the hook 66 by the hook load detection device 68 and, during a step 2080, the comparison of the force F determined in the preceding step with a threshold value F0. These steps are carried out by the hook load detection device or detection device 100.

[0100] Steps 2000 to 2080 are performed by the control unit 74 and the terminal 80 of the lifting device 50 , while steps 2082 and 2084 are performed within the detection device 100 and thus by the magnetic clamping system 20 .

[0101] During step 2062, which is performed within the magnetic clamping system 20, insofar as the transmitter 102 emits an infrared signal SI, which is supposed to be picked up by the receiver 104, in step 2062 the output signal of the receiver 104 is transmitted to the clamp control unit 34. In other words, step 2062 involves collecting the state of the receiver output signal S104, which enables the clamp control unit 34 to determine whether the output signal S104 includes the first value V1 or the second value V2.

[0102] If the outcome of step 1002 is positive, then, as after step 2062, during step 2086, which occurs after step 1002, it is verified whether receiver 104 is in fact receiving infrared signal SI by determining whether signal S104 contains a first value V1.

[0103] If not, the method automatically moves to step 2088, which prompts the operator to attach the hoist 56, and the removal procedure is aborted. The magnetic pads 24 are maintained in a magnetized configuration, and the mold 12 is held fixed within the injection molding machine 4 by the magnetic clamping device 20, and the operator cannot proceed with the mold demagnetization procedure. In other words, demagnetization of the magnetic pads 24 is prevented during step 2088, thereby preventing the mold from falling.

[0104] If the result of the check in step 2086 is positive, i.e. if the output signal S104 has the first value V1 and the receiver 104 is present in step 1002, the magnet clamp control unit 34 considers that the transmitter 102 is in a predetermined position relative to the receiver 104. Then, during a subsequent step, the magnet clamp control unit 34 can authorize the demagnetization of the magnetic pad 24.

[0105] The method then moves automatically to step 2090, which corresponds to step 1004, in which the operator is asked by the control terminal 40 to know whether the locking mechanism 42 is actually in the locked configuration or not. The operator can reply to this question after visually checking the locking mechanism 42. If the operator replies no, or does not reply within a predetermined time Δt, for example 5 seconds, the method moves automatically to step 2092, in which the operator is prompted to lock the locking mechanism 42 by a message displayed on the terminal 80. If the operator verifies in step 2090 that the locking mechanism 42 is in an activated state, the method moves automatically to step 1008 through the logic gate 1010. This check of the locking mechanism limits the risk of holding the mold part 12B with the lifting eyebolt 44 but not the mold part 12A. In a variant, this check is performed in an automatic way by an additional sensor (not shown).

[0106] During a step 1008, the operator activates, by means of the terminal 40, a command to demagnetize the magnetic pads of the clamping system. This cannot be prevented since the above checking step has been successful.

[0107] Thereafter, steps 1012 to 1020 can be performed. These steps are illustrated by the illustration (F) of FIG. 4 using arrows A2, A3, and A4.

[0108] Thus, the authorization to demagnetize the magnetic pad resulting from the check in step 2086, if the authorization is positive, is conditioned on the outcome of the comparison in step 2090.

[0109] Except when action by an operator is required, steps 2086-2092 and 1012-1020 described above are performed automatically by clamp control unit 34.

[0110] In summary, the steps of the dismantling method of the invention involve several components of the installation 2. Steps 1002 to 1006, 1008 to 1014, 2062 and 2082 to 2092 are performed in the magnetic clamping system 20, more specifically by the magnetic clamping control unit 34, by the terminal 40 and by the position detection device 100. Steps 1016 and 1018 are notably performed by the control unit 14 of the injection molding machine. Steps 1020 and 2000 to 2080 are notably performed by the control unit 74, by the terminal 80, by the motor 64 and by the sensor 68 of the lifting device 50.

[0111] More specifically, in accordance with one aspect of the present invention, the magnetic clamping system 20 is configured to perform at least steps 1012, 2062, 2084, 2086, and 2088, and preferably all of steps 1002-1006, 1008-1014, 2062, and 2082-2092.

[0112] 3D illustrates a case where a transmitter 102 that is not at a predetermined position relative to the receiver 104 emits an infrared signal IF, and the infrared signal SI emitted by the transmitter 102 reaches a point that is offset along the X-axis from the sensor 104. This is detected in step 2086 because the output signal S104 of the receiver 104 contains a value V2, which leads to the implementation of step 2088.

[0113] Thereby, the method of the invention allows the magnetic clamp control unit 34 to ensure that the receiver 104 is identified as present and operational during step 1002 and, if the receiver 104 is not identified as present and operational, to continue the detachment method in a manual mode with steps 1004-1020 and a conveying step performed by an operator, or, if the receiver 104 is identified as present and operational, to continue the detachment method in a safe and semi-automatic mode with steps 2000-2092 and then steps 1008-1020.

[0114] The safe nature of the removal method of the present invention is due to the fact that as long as the lifting device 50 is not correctly positioned relative to the injection molding machine 4 during step 2040, or in the event that the load detection device including the sensor 68 does not detect any load on the hook and therefore the hoist 56 is unable to hold the mold 12 during step 2078, the output signal S104 of the receiver 104 maintains the second value V2, which is detected during step 2086.

[0115] In the second and fourth embodiments of the installation 2 shown in Figures 6-7, elements similar to those of the first embodiment have the same reference numbers. Where a part of the installation 2 of the second and third embodiments is described in this detailed description without being shown in the figures, that part is the same as the part described for the first embodiment. On the other hand, where a reference number is used for a part in Figures 6 or 7 without being described in this detailed description, that part is the same as the part having the same reference number in the first embodiment. In the following, the differences of the second embodiment from the first embodiment will be mainly described.

[0116] 6, the transmitter 102 and the sensor 104 are arranged such that the infrared signal SI is emitted in a direction parallel to the Y axis of a Cartesian coordinate system XYZ. The output signal S104 of the sensor 104 is obtained when the transmitter 102 emits the infrared signal SI and the transmitter 102 and the sensor 104 face each other and are aligned along the same straight line D parallel to the Y axis. SI When aligned upward, it contains the first value V1. SI corresponds to a predetermined position of the transmitter 102 relative to the receiver 104. The output signal S104 of the sensor 104 is aligned along a line D when the transmitter 102 is not emitting an infrared signal IF and / or when the transmitter 102 and the sensor 104 are not facing each other. FI When not aligned above, it contains a second value V2.

[0117] 7, the transmitter 102 and the sensor 104 are oriented such that the infrared signal SI is parallel to the X-axis of a Cartesian coordinate system XYZ. The output signal S104 of the receiver 104 indicates that the transmitter 102 is emitting the infrared signal SI and that the transmitter 102 and the sensor 104 are facing each other and aligned along the same straight line D' parallel to the X-axis. SI When aligned upward, it contains the first value V1. SIcorresponds to a predetermined position of the transmitter 102 relative to the receiver 104. The output signal S104 of the receiver 104 is aligned along a line D' when the transmitter 102 is not emitting an infrared signal IF and / or when the transmitter 102 and the sensor 104 are not facing each other. FI When not aligned above, it contains a second value V2.

[0118] straight line D' SI The detection direction along corresponds to the fact that the rail 154 of the lifting device 50 is supported by two carriages 57 which are movably mounted on two beams 55 extending parallel to the Y axis, whereby the hoist 56 is movable on parallel planes along both the X and Y axes, in particular perpendicular to the Y axis.

[0119] In the second and third embodiments, when the transmitter 102 is in a predetermined position, the carriage 52 is vertically aligned with the mold 12 clamped within the injection molding machine.

[0120] In the second and third embodiments, following an approach equivalent to that of the first embodiment, the receiver 104 has a reception zone (not shown) in the form of a frustum of a cone.

[0121] Whatever the embodiment, the detachment method and the magnetic clamping system 20 of the present invention allow a satisfactory positioning of the hoist 56 relative to the injection molding machine 4 to be detected and the demagnetization of the magnetic pads 24 to be authorized. The solution of the present invention has the advantage of being simple and inexpensive while being almost universal, i.e. adaptable to a multitude of operating configurations. Such a solution is also unidirectional, due to the orientation of the communication from the transmitter to the receiver, which does not require a round trip. Such a solution works without a wired link between the transmitter 102 and the receiver 104 of the positioning device 100. The solution of the present invention also has the advantage of being secure and tamper-proof, since the detection of the electromagnetic signal is only possible under unique alignment conditions.

[0122] The invention is not limited to the type of lifting device: in one variant, the lifting device may be a chain or sling type lifting device, and may also be a robot or a crane.

[0123] According to one variant of the invention, the transmission direction of the transmitter 102, the reception direction of the receiver 104 and the reception frustum K 104 can be tilted in all directions with respect to the XYZ axes.

[0124] According to other variants of the invention (not shown), the transmitter can emit electromagnetic signals other than infrared signals, in particular laser signals or unidirectional electroluminescent signals emitted by light-emitting diodes, i.e. LEDs. In such examples, the receiver 104 is adapted to detect the laser signal or the electroluminescent signal.

[0125] The invention is not limited to use within the framework of plastic processing installations, but also applies to other types of installations with machines, in which certain parts of the machine, for example machining centers, are replaced during the machine's service life: more specifically, the invention can also be applied to machining centers with vertically arranged magnetic clamping plates, in which there is a risk of the workpieces falling during demagnetization.

[0126] According to one variant of the invention (not shown) applicable to all embodiments, the hook load detection device, which includes the sensor 68 and means for processing its output signal (not shown), can be configured to determine the mass of the part to be clamped, i.e. the mass of the mould 12 in the embodiment shown, based on the force between the carriage 52 and the hook 66. In such an example, the electromagnetic signal emitted by the transmitter 102 advantageously contains information on the mass of the part to be clamped, determined by the hook load detection device. The receiver 104 is then configured to extract information on the mass of the part to be clamped from the electromagnetic signal received from the transmitter 102 and to communicate it to the magnetic clamp control unit 34. In such an example, when loading the mould 12 into the injection moulding machine 4, or when loading another part to be clamped into another machine, the method of loading the part can include a step, which is executed in the magnetic clamp control unit 34 and which includes comparing the information on the mass of the part to be clamped extracted from the electromagnetic signal emitted by the transmitter 102 with a pre-determined threshold value. If the comparison indicates that the mass of the workpiece to be clamped is greater than the threshold, additional steps can be performed, also in the clamp control unit 34, to prevent the part from being loaded or to generate an alarm. On the other hand, if the comparison indicates that the mass of the part to be clamped is less than the threshold, steps can be performed in the magnetic clamp control unit 34 to authorize the part to be loaded into the machine.

[0127] Thereby, in the example of a mold, when the mold 12 is brought by the hoist 56 to an injection molding machine 4 whose clamping magnetic force is limited to a threshold value, clamping may be prevented or an alarm may be activated prior to such clamping action.

[0128] According to another variant applicable to all embodiments of the invention, the electromagnetic signal emitted by the transmitter 102, for example an infrared signal SI, carries an identification frame Ti for the transmitter, intended to be collected by the receiver 104. 102 In such an example, the method may comprise an additional step (not shown), for example performed between steps 2060 and 2090. During the additional step, the identification frame Ti 102 is a reference identification frame Tref assigned to a transmitter 102 that is assumed to belong to the same location detection device 100 as the receiver 104. 102 If the result of this comparison is negative, i.e., the frame Ti 102 and Tref 102 If they are different, the method returns to step 2088, regardless of the value V1 or V2 contained in signal S104. If the result of this comparison is positive, the method proceeds to step 2090. It is thereby possible to ensure that the signal detected by sensor 104 corresponds to a hoist 56 associated with a row of machines, including the hoist 56 whose clamping plate the receiver is fixed to, and that the signal is not a parasitic electromagnetic signal coming from nearby equipment.

[0129] According to another variant applicable to all embodiments, the receiver 104 is mounted on a fixed part of the installation 2, but offset from the clamping plate 26. This is in order to reduce environmental constraints, especially from a cabling point of view.

[0130] In one variant, the position of the receiver 104 is adapted on the machine by means of a slide or clamping means which act to fix the receiver in one of several possible positions on the machine.

[0131] In a variant, multiple emitters 102 and / or multiple receivers 104 can be used for the same machine, in particular for the same injection molding machine 4 and the same hoist 56. This makes it possible to ensure that the positioning of the hook 66 is correct along two perpendicular directions, in particular when the hoist 56 can move along the X-axis and the Y-axis as in the third embodiment. In such an example, it is possible to combine the orientations of the relevant parts of the position detection device 100 shown in Figures 6 and 7. The subsequent authorization for demagnetization is based on the combined reception of the multiple signals.

[0132] According to another variation of the invention (not shown), the mold parts 12A and 12B are each provided with a lifting eyebolt 44 so that they can be independently manipulated during loading and unloading of the mold from the injection molding machine. In such an example, it is not necessary to provide the locking mechanism 42 and steps 1004 and 2090 of the method are not performed. In such an example, demagnetization of the magnetic pad 24 is independently controlled for the two clamping plates 26 and 28.

[0133] In one variation, the mold 12 may include two or more sections 12A and 12B that are operated together or independently.

[0134] According to another variant, the frustum K104 can be a cone if the detection zone of the receiver 104 is isolated.

[0135] The above-described embodiments and modifications of the present invention can be combined with each other to create new embodiments.

Claims

1. 1. A method for removing at least one workpiece (12) clamped on a magnetic clamping system (20) of an industrial facility (2) using a hoist (56), comprising the steps of: The hoist is a carriage (52) movable in a horizontal plane; - a hook (66) suspended from said carriage and vertically movable; - a hook load detection device (68) configured to determine the force (F) between said carriage and said hook; a hoist control unit (74), The magnetic clamp system (20) comprises: a magnetic clamp control unit (34); at least one magnetic clamping plate (26) including a plurality of selectively magnetizable magnetic pads (24) controlled by said magnetic clamping control unit; a human machine interface (40) connected to said magnetic clamp control unit (34) and used to input commands (1008) for demagnetizing said magnetic pads, In the method of removal, The magnetic clamping system (20) comprises a detection device (100) for detecting the position of the carriage (52) relative to the clamping plate (26), the detection device (100) comprising: a transmitter (102) of an electromagnetic signal (SI) fixed to said carriage and controlled according to said force (F) determined by said hook load detection device (68); a receiver (104) for the electromagnetic signal emitted by the transmitter, the receiver being fixed relative to the clamping plate (26) and configured to provide an output signal (S104), the output signal having a first value (V1) when the receiver receives the electromagnetic signal and a second value (V2) when the receiver does not receive the electromagnetic signal, The method of removing includes: (a) determining (2078) the force (F) between the carriage (52) and the hook (66) by the hook load detection device (68); (b) dividing the force (F) determined in step (a) by a threshold (F ０ ) (2080); (c) activating (2084) the transmitter (102) if the comparison made in step (b) indicates that the force determined in step (a) is greater than the threshold value; (d) during step (c), acquiring (2062) the output signal (S104) of the receiver; (e) determining (2086) which value is contained in the output signal (S104) of the receiver (104), between the first value (V1) and the second value (V2); (f) authorizing input of a command to demagnetize the magnetic pad by the human machine interface (40) if the determination of step (e) indicates that the output signal collected in step (d) includes the first value (V1); and (g) preventing (2088) the input of the command to demagnetize the magnetic pad by the human machine interface (40) if the determination of step (e) indicates that the output signal collected in step (d) includes the second value (V2); The method of removing the adhesive comprises at least

2. 2. The method of claim 1, wherein step (g) (2088) is maintained for as long as the signal collected in step (d) (2062) has the second value.

3. The method of removing according to any one of claims 1 to 2, characterized in that the receiver (104) outputs the output signal (S104) having the first value (V1) when the transmitter (102) is activated and is in a predetermined position relative to the receiver, and the receiver outputs the output signal (S104) having the second value (V2) when the transmitter (102) is not operating and / or is not in the predetermined position relative to a second element.

4. The method of claim 3, wherein the predetermined position of the transmitter (102) faces the receiver (104).

5. The method of detaching according to claim 3 or 4, characterized in that the predetermined position of the transmitter (102) corresponds to a vertical alignment of the part (12) clamped on the magnetic clamping system with the carriage (52).

6. The electromagnetic signal (SI) transmitted by the transmitter is an identification frame (Ti) intended to be collected by the receiver. １０２ ) The method further comprises the steps of: determining whether the identification frame and a reference identification frame (Tref １０２ ) and The method of detaching according to any one of claims 1 to 5, characterized in that if the result of the comparison in step (h) is negative, the input of the command to demagnetize the magnetic pad is prevented (2088) regardless of the values ​​(V1, V2) determined in step (e) (2086).

7. The method comprises: (i) prior to step (c), determining (1004) whether the receiver (104) is in an operational state; (j) if step (i) determines that the receiver is operational, proceeding to step (e); (k) if it is determined in step (i) that the receiver is not in working condition, switching to a manual mode, in which an operator must confirm at least one step (1004, 1006) by answering questions by means of a control terminal (40) connected to the magnetic clamp control unit (34); A method of detaching according to any one of claims 1 to 6, characterized in that it comprises the additional step of:

8. A magnetic clamping system (20) comprising: a magnetic clamping control unit (34); and at least one magnetic clamping plate (26) including a plurality of selectively magnetizable magnetic pads (24) controlled by the magnetic clamping control unit, The magnetic clamping system (20) comprises a detection device (100) for detecting the position of a carriage (52) of a lifting device (50) relative to the magnetic clamping plate (26), the detection device comprising: a transmitter (102) of electromagnetic signals (SI) fixed to said carriage (52); a receiver (104) of the electromagnetic signal emitted by the transmitter, the receiver being fixed relative to the clamping plate and configured to provide an output signal (S104) having a first value (V1) when the receiver receives the electromagnetic signal and a second value (V2) when the receiver does not receive the electromagnetic signal, 8. A magnetic clamping system, characterized in that the clamping system is configured to carry out at least steps (c) to (g) of the method according to any one of claims 1 to 7.

9. 9. The magnetic clamping system of claim 8, wherein the electromagnetic signal is an infrared signal (SI) and the receiver (104) is configured to detect infrared signals.

10. 9. The magnetic clamping system of claim 8, wherein the electromagnetic signal is emitted from a laser diode or a light emitting diode, and the receiver is configured to detect the laser signal or the light emitting signal.

11. 11. A magnetic clamping system according to claim 8, characterized in that the receiver (104) is oriented along a vertical axis and that the receiving zone of the receiver has the shape of a cone or a truncated cone (K104) centered on the vertical axis.

12. 11. A magnetic clamping system according to claim 8, characterized in that the receiver (104) is oriented along a horizontal axis (X, Y) and that the receiving zone of the receiver has the shape of a cone or a truncated cone (K104) centered on the horizontal axis.

13. 13. The magnetic clamping system according to claim 8, characterized in that the receiver (104) comprises a microcontroller liable to communicate the first value (V1) or the second value (V2) contained in the output signal (S104) to the magnetic clamp control unit (34).

14. The magnetic clamp system according to any one of claims 8 to 13, characterized in that the receiver (104) is configured to output presence information (S104) to the magnetic clamp control unit (34).

15. 1. A method for loading at least one workpiece (12) to be clamped into a magnetic clamping system (20) of an industrial installation (2) using a hoist (56), comprising the steps of: The hoist is a carriage (52) movable in a horizontal plane; - a hook (66) suspended from said carriage and vertically movable; - a hook load detection device (68) configured to determine the force (F) between said carriage and said hook; a hoist control unit (74), In the method of loading, - the magnetic clamping system (20) is as claimed in one of claims 8 to 14, - the hook load detection device (68) is configured to determine the mass of the workpiece (12) to be clamped based on the force (F) between the carriage and the hook; the electromagnetic signal (SI) emitted by the transmitter (102) comprises information about the mass of the part to be clamped, as determined by the hook load detection device (68); the receiver (104) is configured to extract the information of the mass of the workpiece from the electromagnetic signal received from the transmitter and to communicate it to the magnetic clamping control unit (34) of the magnetic clamping system (20); - the detachment method is a step performed by the magnetic clamping system (20) and (l) comparing the information extracted from the electromagnetic signal regarding the mass of the part to be clamped with a predetermined threshold; (m) preventing loading or issuing an alarm if the comparison in step (l) indicates that the mass of the part to be clamped is greater than the threshold; (n) authorizing the loading if the comparison in step (l) indicates that the mass of the part to be clamped is less than the threshold value; A method of loading, comprising at least the steps of:

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