FR2779669A1 - Safety cutout and protection device protecting machine operators against mechanical, electrical or thermal hazards - Google Patents

Abstract

The sensors, antennae and associated circuits transmit coded monitoring signals to a detector mounted on hazardous machinery. If a part of the body such as a hand has, for example, been put within a tool travel range, the detector picks up a radio transmitted signal, stops the machine and triggers an alarm. The sensors, circuits and antennae are mounted on flexible printed circuits mounted within a protective garment such as glove of suit. The conductive tracks may be attached to the fabric as wire, braid, metal powder or colloidal metal gels. The sensors can analyze electric fields, radioactivity, heat flux and proximity. Sensors are also provided to verify that the protective garment or accessory is being worn. A second detector within the read-out zone controls the continuous transmission of coded signals from the device. If the operator's access code does not match these coded signals the machine can be stopped.

Description

Safety device for driving a machine tool.

  The invention relates to a safety device for controlling a

  machine tool driven by a mechanism.

  The safety of people working on dangerous machine tools (shears, presses) is generally ensured by mechanical protection means or light barriers. The protection obtained with

  such devices do not provide total security.

  The object of the invention is to improve the safety of people working on machine tools, and to stop the operation of the

  machine if security is no longer ensured.

  The safety device is characterized in that it comprises - a protective glove equipped with an electronic circuit for transmitting a coded monitoring signal, said electronic circuit being mounted on a flexible printed circuit inside the glove, - first means for inhibiting the emission of the coded signal when the glove is not put on by the user, - and a first detector secured to the fixed frame of the machine for picking up the coded signal, and stopping the machine when the hand gloved crosses an area

  dangerous tool travel.

  According to a characteristic of the invention, the first means for inhibiting the emission of the coded signal are formed by a sensor for detecting human tissue. The sensor detects the presence of the hand by infrared or

  capacitive, or by means of a mechanical micro-contact.

  Preferably, a second detector is housed in a reading area to control the permanent emission of the coded signal from the glove (positive security). According to another characteristic of the invention, the second means inhibit the emission of the coded signal in the event of non-conformity of the access code entered by the user. According to a preferred embodiment, the transmission of the coded signal from the glove is carried out by radio, the electronic circuit of the glove

  comprising at least one transmitter circuit or a first transmitter circuit -

  receiver associated with a first antenna, while the first detector comprises a receiver circuit or a second transmitter-receiver circuit

  associated with a second fixed antenna.

  The second detector comprises a third antenna housed in the reading zone, and coupled with a third transmitter-receiver circuit, connected with the second transmitter-receiver circuit to a decoding circuit at

  microprocessor, to which a keyboard and a control display are connected.

  According to a development of the invention, the transmission link between the

  glove and the machine can also be obtained by infrared means.

  Other advantages and characteristics will emerge more clearly from the

  description which will follow of an embodiment of the invention, given as

  non-limiting example and shown in the accompanying drawings in which: Figure 1 is a schematic view of the machine tool equipped with the safety device according to the invention; - Figure 2 shows a block diagram of an electronic circuit with radio transmission - Figure 3 shows a detail of Figure 2;

  - Figure 4 is a variant of Figure 2.

  Referring to Figure 1, a machine tool 10 formed by way of example by a press or shears, is equipped with a base 12, a work table

  14 horizontal, and a frame 16 for supporting the cutting or striking tool 18.

  The tool 18 is movable at the rear of the work table 14, thanks to a drive mechanism (not shown) with vertical movement controlled by control means. The handling of the sheets or materials to be cut or machined is carried out by the user on the work table 14, when the tool 18 is in the inactive position. The activation of the control means then causes the tool 18 to descend to carry out the machining operation

or folding.

  To avoid any risk of injury to the hands in the area of movement of the tool 18, the user wears at least one protective glove 20 equipped with an electronic safety circuit 22. A first detector 23 is disposed on the fixed frame 16 above the tool 18, and picks up a coded monitoring signal transmitted by the electronic circuit 22 of the glove 20 to stop the drive mechanism of the tool 18 as soon as the user approaches his hand in the dangerous zone of travel of the tool 18. The components of the electronic circuit 22 are mounted on a flexible printed circuit, based on textile which the conductive polymer uses in the manufacturing process of this circuit flexible, and produced according to known methods described by way of example in document EP 592 285. The flexible printed circuit can be easily integrated into

  inside the glove 20, without any discomfort for the user.

  FIG. 2 shows a first embodiment of the electronic circuit 22 with radioelectric transmission of the coded signal. A hand presence sensor 24 is connected to a switch 26 for controlling a high frequency transmitter circuit 28 associated with a first antenna A1. When the user puts on the glove 20, the sensor 24 delivers an unlocking logic signal to the switch 26 to authorize the operation of the transmitter circuit 28, which transmits a signal coded at high frequency by the first antenna A1. The detection of the hand inside the glove 20 is carried out by means of a sensor 24 for detecting human tissue of the infrared or capacitive type, or by a mechanical micro-contact. If the user forgets or neglects to wear the glove 20, the sensor 24 remains inactive, leading to the blocking of the switch 26 to inhibit the operation of the

transmitter circuit 28.

  The emission of the signal coded by the first antenna A1, is picked up at the level of the machine 10 by a second fixed antenna A2 coupled to a receiver circuit 30 constituting the first detector 23 of FIG. 1. The receiver circuit 30 is connected to a decoding circuit 32 intended to control the putting into service or stopping of the mechanism M. The decoding circuit 32 is arranged to validate the operation of the mechanism M, if the second antenna A2 picks up the high frequency coded signal coming from the glove 20, and if the distance d separating the first

  antenna A1 of the second antenna A2 is sufficient.

  In FIG. 3, the decoding circuit 32 comprises, for example, two doors 34, 36 connected to a logic circuit 38. The first door 34 delivers a validation signal to the input E1 of the logic circuit 38 in the presence of a coded signal received by the second antenna A2. The second gate 36 sends a stop signal to the input E2 when the first antenna A1 approaches too close to the second antenna A2. The output of the logic circuit 38 controls a relay 40 supplying the mechanism M. According to the variant of FIG. 4, the decoding circuit 132 of the machine is provided with a positive security microprocessor, to which a keyboard 42 is connected for entry of parameters and access code, and a control display 44. The keyboard 42 and display 44 assembly is carried by a fixed support

  to the frame 16 in the vicinity of the work table 14.

  The glove 120 comprises a first transmitter-receiver circuit 128 associated with the first antenna A1 for transmitting the coded signal at high frequency. The emission is authorized after validation by the sensor 24 of the presence of the hand, which is connected to an electronic coding-decoding circuit 126. An emergency stop switch 45 is connected to the electronic circuit 126 to stop the transmission in the event of an incident, causing the mechanism M to stop immediately. At the machine, the second antenna A2 is coupled to a second transmitter-receiver circuit 130 connected to the decoding circuit 132 to detect the coded signal coming from the first antenna A1, so that

  stop the mechanism M when the glove 120 reaches the danger zone.

  The user first types an access code on the keyboard 42 to avoid the

  commissioning of machine 10 by an unauthorized person.

  A third antenna A3 is placed in a reading zone 48 situated on the work table 14 in front of the danger zone. The third antenna A3 is associated with a third transmitter-receiver circuit 50, which is connected to the decoding circuit 132 to constitute a second detector 46, shown diagrammatically in FIG. 1. The second detector 46 constantly checks the emission by the glove 120 coded high frequency signal, signifying the proper functioning of the first transmitter circuit

  receiver 128 when the glove 120 is in the reading area 48.

  An accumulator is mounted on the printed circuit of the glove 120 for supplying the circuits 126, 128. A supply circuit is provided in the

  machine 10 for the different circuits 130, 132, 50.

  The accumulator can be removed in the glove 120, if a

  induction power circuit housed in the reading area.

  The operation of the machine safety device according to FIGS. 1 and 4 is as follows: The user puts on the glove 120 so as to activate the sensor 24 causing the emission of the coded signal at high frequency by means of the first antenna A1. Activation of the sensor 24 prevents any emission of the coded signal in the event of the glove 120 being deposited on the reading area 48 without the introduction of the hand. After the entry of the access code on the keyboard 42 of the machine, the third transmitter-receiver circuit 50 picks up the coded signal coming from the first antenna A1, and the decoding circuit 132 checks the correct functioning of the electronic circuit. 122 of glove 120, as well as

  belonging to the authorized person.

  The commissioning of the mechanism M for driving the tool 18 occurs if the following three conditions are met: - hand of the user threaded into the glove 120, - normal operation of the first transmitter-receiver circuit 128 for continuous transmission of the high frequency coded signal, - acceptance by the decoding circuit 132 of the access code entered on the

keyboard 42.

  The operation of the machine tool 10 is then possible as long as the distance d between the two antennas A1 and A2 is sufficient. As soon as the glove 120 approaches the danger zone, the second transmitter-receiver circuit 130 sends a command order to the decoding circuit 132 to stop the mechanism M.

  The access code can be entered on the keyboard 42 by means of the gloved hand.

  In this case, the third antenna A3 (FIG. 1) is extended from the reading area 48 to the support of the keyboard 42 so as to allow the reading of the signal coded by the third transceiver circuit 50, when the user enter their access code, and without placing their gloved hand in the area

reading 48.

  According to a development of the invention, the radio transmission implemented by the electronic circuit of the glove 20 or 120 can be replaced by any other transmission link, in particular infrared. In this case, the circuit 28, 128 of the glove is constituted by a light-emitting diode, and

  the detectors 23, 46 are formed by infrared relays.

Claims (10)

  1. Safety device for controlling a machine tool (10) driven by a mechanism (M), characterized in that it comprises: - a protective glove (20, 120) equipped with an electronic circuit (22 , 122) for transmitting a coded monitoring signal, said electronic circuit being mounted on a flexible printed circuit inside the glove, - first means for inhibiting the emission of the coded signal when the glove (20, 120) is not threaded by the user, - and a first detector (23) integral with the fixed frame (16) of the machine (10) for picking up the coded signal, and stopping the machine when the gloved hand   crosses a dangerous zone of travel of the tool (18).   2. Safety device according to claim 1, characterized in that the first means for inhibiting the emission of the coded signal are formed by a   human tissue detection sensor (24).   3. Safety device according to claim 2, characterized in that the   sensor (24) detects the presence of the hand by infrared or capacitive means.   4. Safety device according to claim 2, characterized in that the sensor (24) detects the presence of the hand by means of a mechanical micro-contact. 5. Safety device according to claim 1, characterized in that a second detector (46) is housed in a reading zone (48) for checking   permanent transmission of the coded signal from the glove (20, 120).   6. Safety device according to claim 1, characterized in that second means inhibit the emission of the coded signal in the event of non-compliance   the access code entered by the user.   7. Safety device according to any one of claims 1 to 6,   characterized in that the transmission of the coded signal from the glove (20, 120) is carried out by radio, the electronic circuit (22, 122) of the glove   comprising at least one transmitter circuit (28) or a first transmitter circuit -   receiver (128) associated with a first antenna (A1), while the first detector (23) comprises a receiver circuit (30) or a second circuit   transceiver (130) associated with a second fixed antenna (A2).   8. Safety device according to claim 7, characterized in that the second detector (46) comprises a third antenna (A3) housed in the reading zone (48), and coupled with a third transmitter-receiver circuit (50), connected with the second transmitter - receiver circuit (130) to a decoding circuit (132) with microprocessor, to which a keyboard (42) are connected and a control display (44).   9. Safety device according to claim 8, characterized in that the supply of the electronic circuit (22, 122) of the glove (20, 120) takes place at   from the machine by means of an induction supply circuit.   10. Safety device according to one of claims 1 to 6, characterized in   that the transmission of the coded signal from the glove takes place by infrared or radio.