WEARABLE SAFETY DEVICE AND SYSTEM FOR SAWING, CUTTING AND MILLING MACHINES

Technical field

[0001] The present disclosure relates to a safety device and system for sawing, cutting, milling and press machines and operation method thereof, in particular the disclosure relates to a system for interrupting machine operation when a protected body part of the machine operator is detected nearer than a certain threshold from the injury-causing moving tool of the machine, for example the sawing, cutting or milling moving tool.

Background Art

[0002] The Personal Protective Equipment (PPE) being a device or product, for single use by the worker, for protection against risks which threaten safety and health, the present disclosure is useful in that it improves worker safety.

[0003] PPEs types may vary depending on the type of activity or risks that could threaten a worker's safety and health and on the body part meant to be protected, such as:

• Hearing protection: noise dampers or ear protection;

• Respiratory protection: masks and filter;

• Visual and facial protection: goggles and face shields;

• Head protection: helmets;

• Hands and arm protection: Coats, gloves and hoses;

• Leg and feet protection: pants, shoes, boots and half-boots;

• Fall Protection: safety belts and straps.

[0004] Document US20120167729 discloses a safety system that prevents cutting machine operators from being accidentally carried through the infeed chute into the machine's cutting mechanism. An operator wears a safety device on his wrist and/or ankle and/or in a glove. The safety device has a magnet. A sensor array is mounted on opposing sides of the cutting machine's infeed chute. The magnetic field of the safety device induces a current in the sensor array as it moves in the proximity of the sensor array. The safety system generates a signal which is proportional to the sum of the induced currents. When the signal exceeds a threshold, the safety system shuts off power to the feed mechanism and/or the cutting blades of the cutting machine, preventing injury to the operator. Document US20120167729, for example, will not protect the operator if the safety device is damaged and unable to act upon the magnetic field for signalling the sensor array to shut off the machine, nor even if the operator is not wearing the safety device.

[0005] Document US20120167729 will only protect indirectly the operator from the rotating cutting mechanism through the signal from the sensors placed in the vicinity of the cutting mechanism. If the magnet and sensor array are to function providi ng adequate physical protection of the operator, then the distance at which the signal threshold is reached must be rather far from the machine to avoid any danger of physical harm. For example, in a normal work situation of the system of US20120167729, it is not practical to set the appropriate threshold - too low a threshold, the machine shuts off too easily and the work of the operator is frequently disrupted and inefficient; or too high a threshold, the machine only shuts off when physical harm is already very likely to occur.

[0006] These facts are disclosed in order to illustrate the technical problem addressed by the present disclosure.

General Description

[0007] It is described a wearable safety device for covering a body part of an operator of a machine tool, comprising:

a. a support material for covering said body part;

b. one or more magnetic sensors placed along the support material of the wearable safety device;

c. an electronic communication unit comprising a battery; wherein the electronic communication unit is configured to emit a wireless signal which is interrupted if any of the magnetic sensors detects a magnetic field above a predetermined threshold, such that the machine tool is disabled from operating when the wireless signal is not received by the machine tool.

[0008] In an embodiment, the electronic communication unit is configured to not emit the wireless signal if the electric connection between the electronic communication unit and the magnetic sensors is interrupted.

[0009] In an embodiment, the magnetic sensors are electrically normally closed and connected in series to the electronic communication unit.

[0010] In an embodiment, said device is a glove, sock, arm sleeve, legging, trousers, shorts, shoe, boot, face mask, coat, jacket, shirt, helmet, knee pad, elbow pad, goggles, spat or gaiter, and the one or more magnetic sensors are placed along the device at locations corresponding to the extremities of the body to be covered.

[0011] In an embodiment, the device is a glove and the extremities are the fingers, or wherein the device is a shoe and the extremities are the toes.

[0012] In an embodiment, the magnetic sensors are Hall-effect sensors or magnetometer sensors.

[0013] It is also disclosed a safety system comprising a wireless signal receiver for receiving the wireless signal emitted by a wearable safety device according to any of the previous devices, wherein the wireless signal receiver is configured to enable a machine tool to operate only when the wireless signal is received by wireless signal receiver.

[0014] It is also disclosed a tool machine comprising the safety system according to the previous system, and comprising one or more magnets arranged in a movable part of the tool machine which has injury risk to the operator, such that a magnetic field above the predetermined detection threshold of the magnetic sensors is provided externally to the movable part, wherein the machine tool is configured to be enabled to operate only when the wireless signal of the wireless signal receiver is received by the wireless signal receiver.

[0015] In an embodiment, the movable part is a rotatable machine tool and the magnet or magnets are placed in the periphery of the tool along a perimetrical line, in particular the magnets are placed at spaced intervals in the periphery of the tool, further in particular the magnets are placed at equally spaced intervals in the periphery of the tool.

[0016] In an embodiment, the movable part is a rotatable machine tool and the magnets are placed in the periphery of the tool in arrays of two or more magnets,

wherein the magnets of each array are placed such that the magnetic field detection threshold of each magnet overlaps the magnetic field detection threshold of the neighbouring magnet or magnets, and

wherein the arrays are placed at spaced intervals in the periphery of the tool, in particular the arrays are placed at equally spaced intervals in the periphery of the tool.

[0017] In an embodiment, the rotatable machine tool is rotatable along a stadium-shaped perimeter consisting of two semi-circular sections connected by two linear sections, in particular the rotatable machine tool is a band saw and the tool machine is a band saw.

[0018] In an embodiment, the rotatable machine tool is rotatable along a circular perimeter, in particular the rotatable machine tool is a milling tool and the tool machine is a milling machine.

[0019] In an embodiment, the magnets are electromagnetic or a permanent magnets.

[0020] In an embodiment, the tool machine is a sawing, cutting, milling, threading, grooving, parting off, chamfering, profiling, turning, boring, drilling, shearing or press machine.

[0021] The present disclosure is related to the integration of a safety system meant to be implemented in Personal Protective Equipment (PPE) interacting with the machine, equipment or risk-causing element.

[0022] The present disclosure is namely characterized by in that it allows continuously detecting if the operator is wearing the Personal Protective Equipment (PPE) and if he approaches a danger zone, assessing the legitimacy for the use of equipment as well as analyzing other risk magnitudes in the vicinity of the operator.

[0023] A Personal Protective Equipment (PPE) may be a protective garment or outwear, including but not limited to a glove, boot, helmet, goggles, spat or gaiter. [0024] According to an embodiment, the system includes at least:

• Two controllers with digital and analog inputs/outputs and real-time clock. One being arranged on the control/actuation system (fixed device integrated in the machine or equipment) and the other being arranged on the detection system (device integrated with the PPE).

• A digital sensor or switch for proximity detection, which may be inductive, capacitive, based on the Hall Effect, or any other sensor of magnetic nature.

• A radio frequency communication system (transmitter/receiver) carrying out continuous communication between the detection system and the control/actuation system.

• A battery-based power supply for the detection system (either rechargeable or not), and charge level monitoring system thereof. The control/actuation system may be powered by the machine or equipment's own power unit.

• A magnetic field production system (electromagnets or permanent magnets).

[0025] It may also comprise secondary sensors or switches for the monitoring of other physical parameters, wherein the equipment is integrated, namely temperature, humidity, luminosity, acceleration or pulse.

[0026] In an embodiment, it is disclosed a system comprising:

a. magnetic field production device;

b. detection system;

c. control and actuation system.

[0027] In an embodiment, the magnetic field production device may be an electromagnet or a permanent magnet, arranged in the fixed or movable part of the hazardous object, machine or equipment.

[0028] In an embodiment, the detection system may be directly fixed, contained within and applied to the operator's PPE, thus protecting him more effectively.

[0029] In an embodiment, the detection system, via the communication and processing unit, sends a radio frequency signal to the control and actuation system, after receiving the signal from the digital sensor or switch for proximity detection, which may be inductive, capacitive, based on the Hall Effect, or any other sensor of magnetic nature.

[0030] In an embodiment, the detection system may comprise digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect, or any other sensor of magnetic nature connected to a communication and processing unit, the detection system being powered by a rechargeable or non-rechargeable battery, and being able to monitor the charging level thereof.

[0031] In an embodiment, the digital sensor or switch for proximity detection, which may be inductive, capacitive, based on the Hall Effect, or any other sensor of magnetic nature sends a signal to the controller, resulting from the actuation of the magnetic field production device, when the sensor or switch is perpendicularly arranged to at least some of the magnetic field lines, it being possible for the signal to be used to activate a preset safety procedure for the machine or equipment.

[0032] Other types of sensors may be connected, including accelerometers, inclinometers, thermometers, humidity gauges, light or force gauges.

[0033] In an embodiment, the detection system may be incorporated into a glove consisting at least of a palm portion or back of hand portion and at least one finger portion. In another embodiment, the detection system may be incorporated into a boot or shoe or part thereof. In still another embodiment, the detection system may be incorporated into a helmet, glasses, knee pads, elbow pads, a jacket, a shirt, trousers, shorts or objects suitable to be arranged thereon.

[0034] In an embodiment the digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect,, or any other sensor of magnetic nature are connected in a normally closed (NC) circuit, and if the circuit is damaged or interrupted the detection system, via the communication and processing unit, sends a radio frequency signal to the control and actuation system.

Brief Description of the Drawings [0035] The following figures provide preferred embodiments for illustrating the description and should not be seen as limiting the scope of disclosure.

[0036] Figure 1: Schematic representation of an embodiment of a Personal Protective Equipment (PPE), in the present case being a glove, with an embodiment of the system according to the disclosure.

[0037] Figure 2: Schematic representation of an embodiment of a PPE, in the present case being a boot, with a system according to the disclosure.

[0038] Figure 3: Schematic representation of an embodiment of one or more detection systems in communication with a remote control/actuation system according to the disclosure.

[0039] Figure 4: Representation of a block diagram of an embodiment of the system hardware according to the disclosure.

[0040] Figure 5: Representation of the monitoring target areas of a rotating cutting tool according to of an embodiment.

[0041] Figure 6: Schematic representation of an implementation example with a rotating cutting tool of an embodiment of a system according to the disclosure.

[0042] Figure 7: Flowchart representation of the method of an embodiment for using the system.

[0043] Figure 8: Schematic representation of the system according to an embodiment.

[0044] Figure 9: Identification of some hazards meant to be overcome or solved.

[0045] Figure 10: Schematic representation of an embodiment of a Personal Protective Equipment (PPE), in the present case being a glove, with a normally-closed (NC) circuit connecting a plurality of magnet sensors place at the extremity of the glove fingers.

[0046] Figure 11: Schematic representation of an embodiment of a Personal Protective Equipment (PPE), in the present case being a glove, with a circuit connecting a plurality of magnet sensors place at the extremity of the glove fingers and along the glove fingers at spaced intervals. [0047] Figure 12: Schematic representation of an embodiment of a circular rotating cutting tool (for example, the cutting tool of a milling machine) provided with a number of magnets placed at spaced intervals in its periphery.

[0048] Figure 13: Schematic representation of an embodiment of a rotating sawing tool with two semi-circular sections connected by two linear sections (for example, the saw of a band saw machine), the tool being provided with a number of magnets placed at spaced intervals in its periphery.

[0049] Figure 14a: Schematic detail representation of an embodiment of a circular rotating cutting tool provided with a one magnet placed in its periphery.

[0050] Figure 14b: Schematic detail representation of an embodiment of a circular rotating cutting tool provided with a magnet array placed in its periphery.

[0051] Figure 14c: Schematic detail of the substantially perimetrical threshold defined by the combination of the individual magnet thresholds, in comparison with the perimetrical threshold and the injury line. Perimetrical is here meant as an external boundary parallel to the perimeter of the moving tool.

Detailed Description

[0052] Figure 1 shows a schematic representation of a PPE, in the present case being a glove, with a system 100 according to an embodiment of the disclosure.

[0053] The system 100 may include a glove 101 which may include a palm or back of hand portion 102, a plurality of finger portions 103 and thumb portion 104, digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect, or any other sensor of magnetic nature 106 which are coupled to the glove 101 near the end of each finger portion 103 and 104, or any other areas deemed appropriate. A processing and communication unit 105 and one or more magnetic field generating devices 107 are also included. The magnetic field generating device 107 may be an electromagnet or a permanent magnet producing several magnetic field lines, thus forming a magnetic field region.

[0054] The digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 106 are connected in series to each other via a wire connecting them to the processing and communication unit 105, such being designated series connection. The digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 106 may also be directly connected to the processing and communication unit 105, such being designated parallel connection.

[0055] When at least one of the digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 106 are led by the user to interfere with the magnetic field generated by the magnetic field generating device 107, a signal is thus generated. The signal, or an amplified version thereof, may be sent to the processing and communication unit 105.

[0056] The processing and communication unit 105 may process the signal from the digital sensor or switch for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 106 thus providing sufficient data to determine the proximity of the danger zone sending a signal to the remote control and actuation system (not shown in this figure). The later will in turn act according to the predefined procedures, which may be, for example, the immediate immobilization of the hazard source.

[0057] Should the wire connecting the digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 106 to the processing and communication unit 105 be interrupted or broken, the remote control and actuation system shall consider that the system 100 is not in good condition and actuates the safety procedure set for the machine or equipment. [0058] According to an embodiment, the sensors are connected in series and the sensors are normally closed - if any of the lines is interrupted by damage or any of the sensors is triggered, the signal fed to the communication unit will be interrupted.

[0059] According to an alternative embodiment, in the case of parallel connection of the sensors, the communication unit 105 must ensure that if at least one of the detector lines is triggered, either by one of the sensors, or by the interruption by damage of one of the lines, the communication is interrupted such that the machine is stopped. This is usually implemented by a logic 'AND' circuit.

[0060] Figure 2 shows a schematic representation of a PPE, in the present case being a boot, with a system 200 according to an embodiment of the disclosure. The system 200 may include a boot 201, which may include a boot portion, digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 203 which are coupled to the boot 201 near the end thereof, or at any other areas deemed appropriate. A processing and communication unit 202 and one or more magnetic field generating devices 204 are also included. The magnetic field generating device 204 may be an electromagnet or a permanent magnet producing several magnetic field lines, thus forming a magnetic field region.

[0061] The digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 203 are connected in series to each other via a wire connecting them to the processing and communication unit 202, such being designated series connection. The digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 203 may also be directly connected to the processing and communication unit 202, such being designated parallel connection.

[0062] When at least one of the digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 203 are led by the user to interfere with the magnetic field generated by the magnetic field generating device 204, a signal is thus generated. The signal, or an amplified version thereof, may be sent to the processing and communication unit 202.

[0063] The processing and communication unit 202 may process the signal from the digital sensor or switch for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 203 thus providing sufficient data to determine the proximity of the danger zone sending a signal to the remote control and actuation system (not shown in this figure). The later will in turn act according to the predefined procedures, which may be, for example, the immediate immobilization of the hazard source. Should the wire connecting the digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 203 to the processing and communication unit 202 be interrupted or broken, the remote control and actuation system shall consider that the system 200 is not in good condition and actuates the safety procedure set for the machine or equipment.

[0064] Figure 3 shows an example of a system 300 including several arrays of digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 307 in communication with a remote control and actuation device 309 via an antenna 308, according to an embodiment of the disclosure. The glove 304 is similar to the glove in system 100 described in Figure 1, the boots 306 are similar to those in system 200 depicted in Figure 2. System 300 may also include other systems with digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 307 embedded in the user's clothing 303 and 305, respectively, a shirt/a jacket and pants. In addition to these, it may also be embedded in other safety equipment such as a helmet 310 and goggles 301.

[0065] Figure 4 shows a representation of the block diagram implementing the hardware required to implement a system according to an embodiment of the disclosure.

[0066] The system is basically composed of three main blocks: A set of magnetic field generating devices 003;

Detection system 001 (which may be one or several units);

A control/actuation system 002;

[0067] It includes at least:

• Two controllers with digital and analog inputs/outputs and real-time clock. One being arranged on the control/actuation system 002, and the other being arranged in the detection system 001 integrated with the corresponding PPE.

• A digital sensor or switch for proximity detection, which may be inductive, capacitive, based on the Hall Effect, or any other sensor of magnetic nature 008, 009, or 010.

• A radio frequency communication system (transmitter/receiver) consisting of 006 and 014 and carrying out continuous communication.

• A battery-based power supply 007 for the detection system (either rechargeable or not), and charge level monitoring system thereof. The control/actuation system 002 may be powered by the machine or equipment's own power unit 015.

• A magnetic field generating system 003 (electromagnets or permanent magnets) in the case where the sensor used is of the Hall Effect or magnetic type.

[0068] The system may also comprise auxiliary sensors or switches 011 for the monitoring of other physical quantities, wherein the equipment is integrated, namely temperature, humidity, luminosity, acceleration or pulse.

[0069] Elements of the system:

005 and 013 - Microcontroller with digital and analog inputs / outputs and real-time clock (which is normally in the control/actuation system 002);

006 and 014 - A radio frequency communication system (transmitter/receiver) carrying out continuous communication and having lost package analysis. The communication technology may be different, Bluetooth or Zigbee, depending on the environment wherein it is to be inserted.

007 - Battery-based power supply for the detection system (either rechargeable or alkaline), and charge level monitoring system thereof; 008, 009 and 010 - The digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect, or any other sensor of magnetic nature.

011 - Secondary sensors (temperature, humidity, luminosity, acceleration or pulse).

012 and 021 - Wireless, safe, radio frequency or otherwise communication, as mentioned above, between the control/actuation system 002 and detection system 001;

015 - Continuous power supply of the control/actuation system 002, which may derive from the machine/equipment's own power system or alternatively be an independent power supply;

016 - Digital inputs on the control/actuation device 002 to interact with sensors or signals from the machine/equipment;

017 - Analog inputs of the control/actuation device 002, for continuous monitoring of some magnitude integrated within the machine/equipment;

018 - Digital outputs from the control/actuation device 002 to act on the machine/equipment.

019 - Analog outputs from the control/actuation device 002 to act on the machine/equipment.

020 - Communication interface with information network, arranged in the control/actuation system 002.

022 and 023 - magnetic field generating elements, arranged within the control area, on the machine, equipment or object, used when the sensors of such equipment or machine, are of magnetic or Hall Effect nature (permanent magnets or electromagnets).

024 and 025 -magnetic field generated allowing the actuation of the detection system 001.

[0070] Figure 5 shows the control zone 603 is defined from the moment when the secondary safety systems 602 are activated by the passage of system 601. Danger zone 604 is defined by the range of the magnetic field generated by the magnetic field generating devices 605. [0071] Figure 6 represents a possible application example wherein the glove 401 similar to that in system 100 depicted in Figure 1, approaches a hazardous zone, the operator being at risk of severe cut. As the rotary cutting and dangerous object 402 has at least one magnetic field generating device 405 built therein, or a magnetic field generating device 406 is arranged in the vicinity thereof, when the glove 401 approaches the hazardous object 402, the magnetic field generated by 405 or 406 will actuate the digital proximity detection sensors or switches, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 404 embedded in the glove 401, which will send a signal to the processing and communication unit 403, and this in turn shall communicate with the control and actuation system (not depicted in this Figure) thus actuating the safety procedure, which may for instance be the immediate stop of the object 402. In this case instead of the using system 100 in Figure 1, we could use system 200 in Figure 2 or another system implemented in the PPE.

[0072] Figure 7 shows a flowchart of the process 050 for using the system according to an embodiment of the disclosure.

[0073] The process 050 may be performed by a system of digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect, or any other sensor of magnetic nature.

[0074] For illustrative purposes, the process 050 shall be described with reference to the system's block diagram, in Figure 4, namely detection system 001 and control and actuation system 002.

[0075] Process 050 begins in step 051, which represents the connection of the detection system 001. Once connected, the device waits for a warning indicating it has entered in the control zone 603 in Figure 5. Moving to state 052 of monitoring and uninterrupted communication with the control/actuation system 002 unit.

[0076] Once in the state 052, it shall only change to another state if any of the following four conditions are met: Condition 1: exit from the control zone 058, that is, the detection system 001 has left the control zone 058 and is no longer essential to ensure the safety system, thus changing to idle mode 053;

Condition 2: Detection by sensors 059, that is, one or more sensors have been. This may be observed, if the series circuit is interrupted.

Condition 3: Failure in communication 060, that is, as in the monitoring and communication state 052 communication between the detection system 001 and the control/actuation system 002 is continually being established, if a maximum of two packages in information traffic fails, the diagram evolves into the safety procedure 054 defined for the machine or equipment.

Condition 4: turn-off button of the detection system 061, that is, if the button of detection system 001 is turned off and if such command is validated by the control/actuation system 002, the system is inoperative 055, the time of such situation being recorded.

[0077] In fact all state transitions in the system are preferably recorded with date and time of such situations.

[0078] If the process 050 is in state 054, the actuation on the control/actuation system means that a hazardous condition or a communication failure has been detected, the system remaining shut until safety conditions are re-established. So being, the process 050 shall only change from state 054 if safety conditions 062 are validated and a resetting of the machine or equipment 056 is subsequently made in terms of safety as the system. Thus, the system will be in the same conditions as if it were switched on at that time. The process 050 changes from state 053, i.e. the detection system leaves the idle state if an entry into control zone condition 057 is observed.

[0079] Figure 8 represents a possible application example wherein the glove 501 similar to that in system 100 depicted in Figure 1, approaches a hazardous zone, the operator being at risk of entrapment. As the dangerous object 502 is equipped with at least one magnetic field generating device 505, when the dangerous object approaches the glove 501, the magnetic field generated by 505, will actuate the digital sensors or switches for proximity detection, which may be inductive, capacitive, based on the Hall Effect or any other sensor of magnetic nature 504 built into the glove 501, which shall send a signal to the processing and communication unit 503, and the later shall in turn communicate with the control and actuation system (not shown in this Figure) by actuating the safety procedure, which may for instance be the immediate stop of the object 502. In this case, instead of using system 100 in Figure 1, we could use system 200 in Figure 2, or another system implemented in the PPE. The magnetic field generating device 506 may also be arranged in a zone wherein it is not movable, yet effectively protecting the operator of the hazardous object 502.

[0080] According to an embodiment, the following table depicts the key variables and timings involved in avoiding personal injury in a rotating tool machine. It is clear from the data below that there is a compromise between the stopping distance and the necessary time to interrupt operation of the machine. The stopping distance is the distance between activation and danger (distance between the magnetic detection threshold spatial line and the injury spatial line). A larger stopping distance allows that faster operator movements are not dangerous, giving sufficient time for detection and for stopping the machine. However, a larger stopping distance also means that the operator needs to work further away from the tool to avoid spurious interruptions, thus being less efficient. The time necessary for braking is defined by the braking power and the inertial momentum of the moving parts to be braked, and thus rather difficult to reduce. Thus, it is important to reduce the time required in detecting the magnets by the electronic communication unit and in communicating this detection to the machine for interrupting operation. This can, for example, be achieved by inserting more magnets (or arrays of magnets) into the periphery of the rotating tool. Variable Milling machine Band saw machine

Rotations per minute (based upon

3000 610

milling cutter/band saw full rotation)

Number of magnets (or magnet arrays)

4 12

spaced around the tool periphery

Maximum time necessary for magnet to

5ms 8ms

rotate to reach magnetic detector

Magnetic detector response time 0.2μ5 0.2μ5

Communication delay 10ms 10ms

Digital communication delay due to

10ms 10ms potential lost packet

Machine braking time 30ms 30ms

Total time to brake 55ms 58ms

Intended stopping distance 20mm 20mm

Maximum body member approach speed 364mm/s 344m m/s

Table 1

[0081] Figure 9 depicts of some hazards intended to be overcome or solved by the present disclosure.

[0082] Figure 10 depicts an embodiment of a Personal Protective Equipment (PPE), in the present case being a glove, with a normally-closed (NC) circuit connecting a plurality of magnet sensors place at the extremity of the glove fingers.

[0083] Figure 11 depicts an embodiment of a Personal Protective Equipment (PPE), in the present case being a glove, with a circuit connecting a plurality of magnet sensors place at the extremity of the glove fingers and along the glove fingers at spaced intervals. Preferably, the circuit is a normally-closed (NC) circuit. [0084] Figure 12 depicts an embodiment of a circular rotating cutting tool (for example, the cutting tool of a milling machine) provided with a number of magnets placed at spaced intervals in its periphery.

[0085] Figure 13 depicts an embodiment of a rotating sawing tool with two semi-circular sections connected by two linear sections (for example, the saw of a band saw machine), the tool being provided with a number of magnets placed at spaced intervals in its periphery.

[0086] For both figures 12 and 13, the following is pertinent. The moving tool is provided with the magnets of a first magnet array 120 130 at the periphery of the moving tool. The moving tool has cutting/saw/mill elements (blade, cutting insert, saw tooth) 125 135. These define a danger zone 126 136 where a body part of the operator will be injured by said cutting element 125 135.

[0087] There is a line depicting the activation threshold 121 131 where the magnet field is sufficient to activate a magnetic sensor. This threshold is defined by the intensity of the magnetic field generated by the magnet and by the sensitivity of the magnetic sensor. Adjusting these is a normal activity already carried out in the technical field of magnets and magnetic sensors. There is also a line depicting the safety distance threshold 122 132 for interrupting the machine operation. The further away this line is from the cutting element, the safer the system is, but the operation will be less efficient because more unnecessary interruptions will be generated because of close, but not dangerous, operator movements.

[0088] The magnet array 120 130 comprises a plurality of magnets placed at spaced intervals at the periphery of the moving tool, sufficiently close and along the line of movement/rotation of the tool such that the detection threshold of the combined magnet array will be a substantially perimetrical threshold along the periphery of the tool in an area where the magnet array is located. Perimetrical is here meant as an external boundary parallel to the perimeter of the moving tool. [0089] The magnetic sensors can be those that operate continuously. Alternatively, the magnetic sensors are those that operate periodically, i.e. suspending operation for periodic periods of time. This has the advantage of saving power or enabling sensors that operate in such a way, for example. As the tool rotates/moves, the sensor will switch on and off into reading mode. One way to depict this is in Fig. 12/13, where the sensor has been "multiplied" around/along the rotating/moving tool. For example, two"multiplied" positions of a magnetic sensor are depicted 129a 129b / 139a 139b.

[0090] The sensor active reading period 123 133 is the period where the sensor reads the magnetic field in order decide whether to activate the sensor signal. The sensor operation period 124 134 is the total sensor period and comprises a suspended reading period of saving power and an active reading period 123 133. The tool is also provided with magnets of a second magnet array 127 137 at the periphery of the moving tool. This second magnet array 127 137 is preferably located at an opposite location in respect of the first magnet array 120 130 at the periphery of the moving tool. This has the advantage of reducing the time a magnet needs to rotate/move before it reaches the detection threshold of the magnetic sensor.

[0091] Figure 14a depicts an embodiment of a circular rotating cutting tool provided with a one magnet placed in its periphery. Figure 14b depicts an embodiment of a circular rotating cutting tool provided with a magnet array placed in its periphery.

[0092] Fig. 14a depicts a single magnet 140 which a moving tool is provided at its periphery. In Fig. 14b, a moving tool is provided at its periphery with a plurality of magnets 140a 140b 140c of a magnet array. The magnet array comprises a plurality of magnets 140a 140b 140c placed at spaced intervals at the periphery of the moving tool.

[0093] The magnetic sensors are those that operate periodically, thus as above, the two "multiplied" positions of a magnetic sensor 149a 149b are shown. The danger zone 146 is where a body part of the operator will be injured by the cutting/saw/milling element of the moving tool. There is a line depicting the activation threshold 141 where the magnet field is sufficient to activate a magnetic sensor. This threshold is defined by the intensity of the magnetic field generated by the magnet and by the sensitivity of the magnetic sensor. There is also a line depicting the safety distance threshold 142 for interrupting the machine operation. The further away this line is from the cutting element, the safer the system is, but the operation will be less efficient because more unnecessary interruptions will be generated because of close, but not dangerous, operator movements.

[0094] As can be easily seen form Figure 14a, a single magnet will not be able to avoid dangerous risks, because depending on the operation timing of the sensor, the sensor will not align with the magnet position and the detection threshold 141 will be circular, centred around the magnet 140. This way the desired activation threshold 142 is not achieved and even sometimes a sensor position 149b may even by at a position where injury is possible as the injury line 146 is not respected.

[0095] As can be seen from Figure 14b this is solved by providing an array of magnets where the activation threshold 146 is formed by the merging of each magnet activation threshold 141 to form a substantially perimetrical activation threshold. The magnets are placed at spaced intervals at the periphery of the moving tool, sufficiently close and along the line of movement/rotation of the tool such that the combined detection threshold 147 of the combined magnet array will be a substantially perimetrical threshold along the periphery of the tool in an area where the magnet array is located.

[0096] As can be seen from Figure 14c, typically, the substantially perimetrical threshold 147, defined by the combination of the individual magnet thresholds, will be a threshold which preferably deviates from the perimetrical threshold 142 by a relatively small amount. In particular the deviation r' is between 0-30%; 0-20%; 0-10%; or 0-5% in respect of the radius r of an individual magnet threshold. A smaller r' will normally require the array magnets to be placed closer together, thus requiring more magnets to cover the same perimetrical length. Conversely, a larger r' will require less magnets, but a larger deviation r' means that the boundary between operation and interruption of the machine will be less precise. This is detrimental to the efficiency of the human operator, because the operator will not trust the system as much to preserve his safety. If the deviation r' is even larger, there could even be a risk of injury because the detection threshold 147 may dangerously approach the injury line 146.

[0097] The term "comprising" whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. Flow diagrams of particular embodiments of the presently disclosed methods are depicted in figures. The flow diagrams do not depict any particular means, rather the flow diagrams illustrate the functional information one of ordina ry skill in the art requires to perform said methods required in accordance with the present disclosure.

[0098] It will be appreciated by those of ordinary skill in the art that unless otherwise indicated herein, the particular sequence of steps described is illustrative only and can be varied without departing from the disclosure. Thus, unless otherwise stated the steps described are so unordered meaning that, when possible, the steps can be performed in any convenient or desirable order. Certain embodiments of the disclosure may be incorporated as code (e.g., a software algorithm or program) residing in firmware and/or on computer useable medium having control logic for enabling execution on a computer system having a computer processor, such as any of the servers described herein. Such a computer system typically includes memory storage configured to provide output from execution of the code which configures a processor in accordance with the execution. The code can be arranged as firmware or software, and can be organized as a set of modules, including the various modules and algorithms described herein, such as discrete code modules, function calls, procedure calls or objects in an object-oriented programming environment.

[0099] The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof. The above described embodiments are combinable. The following claims further set out particular embodiments of the disclosure.