EP3372767B1

EP3372767B1 - Safety device for closing inspection doors

Info

Publication number: EP3372767B1
Application number: EP18160261.6A
Authority: EP
Inventors: Loris Marchesi; Guglielmo Pellacani; Ermes Prati
Original assignee: Mix Srl
Current assignee: Mix Srl
Priority date: 2017-03-09
Filing date: 2018-03-06
Publication date: 2019-07-24
Anticipated expiration: 2038-03-06
Also published as: EP3372767A1; IT201700025960A1

Description

The present invention relates to a safety device for inspection doors of machines with moving parts.
A safety device for inspection doors of the known art is disclosed in US7,814,621 B1 .
Industrial machines are known which are provided with a box-like enclosure inside which there is a chamber for accommodating moving parts designed to perform various operations. In particular, machines are known which have moving parts such as rotating shafts provided with tools suitable for example to mix, shred or move the material being processed. These machines generally have one or more inspection ports formed on the box-like enclosure and closed by corresponding hinged doors, which must be opened in order to perform cleaning or maintenance interventions or to check visually the material being processed.
In order to avoid risks for the health and safety of assigned personnel, currently applicable statutory provisions regarding safety requires machine manufacturers to provide appropriate systems for controlling the opening of the inspection doors which comprise a safety electric lock mounted between the door and the outside of the box-like enclosure, which is normally locked closed in order to prevent the opening of the door and is actuated to open by a safety electrical panel.
Typically, the main body of the electric lock is mounted on the outside of the enclosure at one of the free sides of the inspection port and the actuator is coupled to the door.
This electrical panel is provided with a mushroom-shaped switch and is connected to a sensor for detecting the stopping of the actuation motor of the rotating shaft and with a sensor for checking for the absence of rotation at the rotating shaft and allows the opening actuation of the electric lock only when the operator presses the mushroom-shaped button and the sensors detect that both the actuation motor and the rotating shaft are motionless.
As is known, electric locks are constituted generally by a main body which is associated with a head provided with one or more actuator insertion openings, so-called "key". When the door is closed, the electric lock is closed and the actuator is kept locked in its seat by activating a stroke limit sensor, which sends to the electrical panel a signal for clearance to start the actuation motor. When the electric lock is actuated to open, the actuator is released, so as to allow the opening of the door.
By means of the system for controlling the opening of the door described above the operator should be placed in safety conditions that are adequate for the execution of his duties.
However, even these safety systems of the known type are not free from drawbacks, which include the fact that the risk remains that the electric lock might be tampered with, by inserting a spare actuator in the corresponding seat, so as to allow the actuation of the motor even when the door is open.
Typically, this tampering of the safety system, despite being unauthorized and contrary to currently applicable safety standards, is performed in order to speed up the execution times of cleaning and maintenance interventions, especially if they must be performed rather frequently so as to not have to wait for the opening times of the electric lock, or due to negligence or unreliability of the assigned operators or due to the need to monitor the machine during operation in order to understand the nature of certain malfunctions or failures.
However, this tempering makes safety systems of the known type entirely ineffective, exposing operators to a serious risk of injury or even death should they intervene inside the machine while the rotating shaft is in operation. It should be considered that for large machines the operator, by leaning in through the inspection port, might fall into the chamber or in any case remain crushed by the moving parts.
The aim of the present invention is to eliminate the drawbacks described above of the background art, providing a safety device for inspection doors of machines with moving parts that allows to avoid tampering with the electric locks and to prevent the opening of the doors in conditions other than the design conditions, ensuring the regular safe operation of the machines, without risks for the health and safety of the assigned operators.
Within this aim, an object of the present invention is to be able to adapt it easily to various machine types and configurations.
A further object of the present invention is to be able to incorporate various types of commercially available electric lock.
Another object of the present invention is to not entail onerous and expensive structural modifications to machines of the known type.
A still further object of the present invention is to have a structure which is simple, relatively easy to provide in practice, safe in use and effective in operation, as well as relatively modest in cost.
This aim and these and other objects which will become better apparent hereinafter are all achieved by the present safety device for inspection doors of machines with moving parts, of the type comprising a substantially box-like enclosure inside which there is a chamber for accommodating moving parts and which is provided with at least one inspection port associated with a door that is pivoted about a rotation axis and can move between a closed configuration and an open configuration of said port, which comprises a safety electric lock provided with a main body associated with a head which bears at least one opening for the insertion of an actuator and is normally closed with the actuator coupled to the main body so as to prevent the opening of the door and is associated with opening actuation means for the release of the actuator so as to allow the opening of said door, characterized in that said electric lock is adapted to be arranged proximate to said rotation axis with the main body associated with said enclosure and in that it comprises an articulation arm which can be associated with said door and is pivoted about a rotation pivot which can be associated with said enclosure at said rotation axis, which is associated with a tab provided with a through slot, the tab being adapted to obstruct at least partially the opening for the insertion of the electric lock when the actuator is disengaged and the arm rotates between the closed and open configurations of the door and to keep free the opening for the insertion of the actuator, passing through the slot and the locking of the rotation of the arm in the closed configuration of the door
Further characteristics and advantages of the present invention will become better apparent from the detailed description of a preferred but not exclusive embodiment of a safety device for inspection doors of machines with moving parts, illustrated by way of nonlimiting example in the accompanying drawings, wherein:

Figure 1 is a perspective view of a portion of a machine provided with a safety device for inspection doors according to the invention, with the corresponding door in the closed configuration;
Figure 2 is a view, similar to Figure 1, with the door in the open configuration;
Figure 3 is a perspective view of the device according to the invention with the door and the electric lock closed;
Figure 4 is a sectional view of the device of Figure 3;
Figure 5 is a perspective view of the device according to the invention with the door closed and the electric lock open;
Figure 6 is a sectional view of the device of Figure 5;
Figures 7 and 9 are perspective views of the device according to the invention with the electric lock open and the door in successive opening steps;
Figures 8 and 10 are sectional views of the device respectively of Figures 7 and 9.

With particular reference to the figures cited above, the reference numeral 1 generally designates a safety device for inspection doors of machines with moving parts.
The device 1 can be advantageously incorporated in a machine 100 of the type that comprises a substantially box-like enclosure 101 inside which there is a chamber 102 for accommodating moving parts (not shown) and which is provided with at least one inspection port 103 which is associated with a corresponding door 104 which is hinged about a rotation axis A and can move between a closed configuration (Figure 1) and an open configuration (Figure 2).
The shape and the dimensions of the enclosure 101 and of the corresponding chamber 102 may the any, and so can be the number, location and shape of the ports 103 and of the corresponding doors 104.
Furthermore, the rotation axis A of the door 104 can have any arrangement with respect to the enclosure 102.
The machine 100 is provided with moving parts (not shown) which are configured as a function of the industrial application for which it is intended. Typically, these moving parts can be constituted by one or more rotating shafts provided with tools, for example, for the mixing, shredding or movement of the material being processed.
In the embodiment shown, the enclosure 101 has a cylindrical shape and the port 103 is substantially rectangular and the corresponding door 104 thereof is hinged along a rotation axis A which is parallel to the longitudinal extension of said enclosure.
Preferably, there are manual quick coupling hooks 105 for further locking of the door 104 in the closed configuration and gas cylinder actuators 106 for supporting the door 104 in the open configuration.
Furthermore, the machine 100 has motor means for the actuation of the moving parts and is provided with a safety electrical panel for the actuation of said motor means, which is connected to first sensors for detecting the actuation of said motor means and to second motor means for detecting the absence of motion at the internal elements of the machine 100 and is provided with a controller which can be operated by an assigned operator, these elements not being shown and described in detail as they are known to the person skilled in the art.
The device 1 comprises a safety electric lock 2 of the conventional type, which is provided with a main body 3 associated with a head 4 which bears at least one opening 5 for the insertion of a key-type actuator 6.
The electric lock 2 is normally locked closed with the actuator 6 coupled to the main body 3 so as to prevent the opening of the door 104 and is associated with opening actuation means to release the actuator 6 so as to allow the opening of the door 104. Such actuation means are of the electric type and are managed by means of the electrical panel described above in manners which are known to the person skilled in the art and therefore are not described in detail.
The electric lock 2 has at least the main body 3 with the corresponding head 4 associated with the enclosure 101, i.e., not integral in rotation with the door 104. In the embodiment shown, the actuator 6 also is associated with the enclosure 101 and does not rotate with the door 104.
Furthermore, the electric lock 2 is arranged proximate to the rotation axis A and not at one of the free sides of the port 103.
The device 1 comprises an articulation arm 7 which is associated with the door 104 and is pivoted about a rotation pivot 8 which is associated with the enclosure 101 at the rotation axis A.
The arm 7 is associated with a tab 9 which is provided with a through slot 11, which is adapted to obstruct at least partially the opening 5 when the actuator 6 is disengaged and the arm 7 rotates between the closed and open configurations of the door 104 and to keep it open for the insertion of the actuator 6 through the slot 11 in the corresponding opening 5 when the arm 7 is in the closed configuration of the door 104.
When the electric lock 2 is closed, the engagement of the actuator 6 through the slot 11 prevents the rotation of the arm 7 and therefore the opening of the door 104.
Usefully, the device 1 comprises a base element 10 which is associated with the enclosure 104 proximate to the port 103, which supports the pivot 8 about which the arm 7 is pivoted and with which the main body 3 of the electric lock 2 is associated.
The electric lock 2 is mounted on the base element 10 so that the direction of extraction/insertion of the actuator 6 is aligned with the extension of the pivot 8.
Preferably, the base element 10 is composed of a block which is associated with the enclosure 101, on which a plate for connection to the main body 3 of the electric lock 2 is screwed which is shaped as a function of the type of electric lock in use. The main body 3 of the electric lock 2 can be mounted on said plate by virtue of locking screws.
In the embodiment shown, the arm 7 is extended along the entire dimension that is transverse to the rotation axis A of the door 104, protruding on the opposite side of said axis in order to support a quick coupling hook 105. Different shapes of the arm 7 are not excluded in any case.
Furthermore, there are two additional rotational supports 107 of the door 104 which are articulated about the rotation axis A by means of respective hinges 108 which are applied to the enclosure 101 and support respective quick coupling hooks 105.
The number, arrangement and shape of the supports 107 can vary as a function of the requirements of the specific application. For doors 104 having small dimensions, the supports 107 might be absent.
The ends that are opposite with respect to the rotation axis A of the arm 7 and of the supports 107 are crossed by a transverse rod 109 which is connected to the gas cylinder actuators 106.
The tab 9 is constituted by a plate which has a substantially circular shape and is extended around the pivot 8.
The plate 9 rotates integrally with the arm 7 about the pivot 8, so that when the arm is in the closed configuration of the door 104 the slot 11 faces the opening 5 so as to allow the insertion/extraction of the actuator 6 into/from said opening.
It should be noted that the plate 9 is arranged proximate to the head 4 of the electric lock 2 in order to avoid transverse insertions of a modified actuator.
Preferably, the plate 9 and the arm 7 are formed integrally monolithically.
Furthermore, the base element 10 comprises an element 12 for covering any secondary insertion openings for the actuator 6 provided on the head 4 of the electric lock 2, which are not visible in the figures.
Furthermore, the device 1 comprises a stem 13 which is inserted so that it can slide in a direction that is substantially parallel to the extension of the pivot 8 by an extent that is equal to an active stroke along a corresponding seat 17 associated with the base element 10. The stem 13 slides integrally with the actuator 6.
As an alternative to or in the absence of the stem 13, the actuator 6 might be associated slidingly directly with the enclosure or be free.
The plate 9 comprises a peripheral notch 14 through which the stem 13 is inserted and the stem 13 is provided with a transverse slot 15, through which the plate 9 can move rotationally during the movement of the arm 7 between the closed and open configurations of the door 104.
With the electric lock 2 open, the stem 13 is translated by an extent that is equal to the active stroke, so as to arrange the slot 15 at the plate 9 in order to allow the rotation of the arm 7 and thus the opening of the door 104.
The device 1 is provided with stroke limiting elements which limit the sliding of the stem 13 along the corresponding seat 17 and are not shown in detail.
In the configuration for the closure of the door 104 with the electric lock 2 closed, the stem 13 is inserted through the notch 14 of the plate 9 and prevents the rotation of the arm 7, since the slot 15 is moved by the plate 9.
The stem 13 therefore acts as a bolt, contributing to the retention of the closed configuration of the door 104.
Furthermore, the device 1 comprises a handle 16 for the movement of the stem 13, which is integral with the actuator 6 of the electric lock 2.
Preferably, the actuator 6 is screwed to the handle 16 by means of locking screws.
The operation of the present invention is as follows.
With the door 104 closed, the hooks 105 fastened and the electric lock 2 closed (Figures 1, 3 and 4), the assigned operator activates on the electrical panel the control for actuating the opening of the electric lock 2. The electrical panel provides clearance to activate the means for the opening actuation of the electric lock 2, so that the actuator 6 is released.
By acting on the handle 16, the stem 13 is translated (to the left with reference to the figures) until the slot 15 is arranged at the plate 9 and the actuator 6 is extracted completely from the plate 9 through the corresponding slot 11 (Figures 5 and 6).
The operator releases the hooks 105 so as to be able to open the door 104.
During the opening rotation of the door 104 the plate 9 obstructs, at first partially and then completely (Figures 7-10), the opening 5 of the electric lock, preventing the insertion of an actuator with the door 104 not perfectly closed.
In practice it has been found that the described invention achieves the proposed aim and objects and in particular the fact is stressed that the device according to the invention allows to avoid any tampering with the systems for controlling the opening of the inspection doors by means of the insertion of actuators in the electric lock when the door is not perfectly closed, ensuring optimum safety conditions for the assigned operators.
Furthermore, the device according to the invention can be applied to any type of industrial machine without particular modifications with respect to known construction methods and allows the use of electric locks of the known type.
The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.
All the details may furthermore be replaced with other technically equivalent elements.
In practice, the materials used, as well as the contingent shapes and dimensions, may be any according to the requirements without thereby abandoning the protective scope of the claims that follow.

Claims

A safety device (1) for inspection doors of machines with moving parts, of the type comprising a substantially box-like enclosure (101) inside which there is a chamber (102) for accommodating moving parts and which is provided with at least one inspection port (103) associated with a door (104) that is pivoted about a rotation axis (A) and can move between a closed configuration and an open configuration of said port, the safety device comprising:
a safety electric lock (2) provided with a main body (3) associated with a head (4) which bears at least one opening (5) for the insertion of an actuator (6) and is normally closed with the actuator (6) coupled to the main body (3) so as to prevent the opening of the door (104) and is associated with opening actuation means for the release of the actuator (6) so as to allow the opening of said door, wherein

said electric lock (2) is adapted to be arranged proximate to said rotation axis (A) with the main body (3) associated with said enclosure (101) and in that it comprises an articulation arm (7) which can be associated with said door (104) and is pivoted about a rotation pivot (8) which can be associated with said enclosure (101) at said rotation axis (A), which is associated with a tab (9) provided with a through slot (11), the tab (9) being adapted to obstruct at least partially the opening (5) for the insertion of the electric lock (2) when the actuator (6) is disengaged and the arm (7) rotates between the closed and open configurations of the door (104) and to keep free the opening (5) for the insertion of the actuator (6), passing through the slot (11) and the locking of the rotation of the arm (7) in the closed configuration of the door (104).
The device (1) according to claim 1, characterized in that said tab (9) comprises a substantially circular plate which is extended around said pivot (8).
The device (1) according to claim 1 or 2, characterized in that it comprises a base element (10) which can be associated with said enclosure (101), which supports said pivot (8) and with which the main body (3) of said electric lock (2) is associated.
The device (1) according to claim 3, characterized in that it comprises a stem (13) which is inserted so that it can slide in a direction that is substantially parallel to said pivot (8) for an extent that is equal to an active stroke along a corresponding seat (17) associated with said base element (10).
The device (1) according to claims 1 or 2 and 4, characterized in that said tab (9) comprises a peripheral notch (14) in which said stem (13) is inserted so as to pass through when the arm (7) is in the configuration for the closure of the door (104) and in that said stem (13) comprises a transverse slot (15) through which said tab (9) can move in rotation in the rotation of the arm (7) between the closed and open configurations of the door (104), with the electric lock (2) open the stem (13) being translated by said active stroke in order to arrange said slot (15) at said tab (9).
The device (1) according to claim 4, characterized in that said actuator (6) and said stem (13) slide integrally, the electric lock (2) being adapted to be arranged so that the direction of insertion/extraction of the actuator (6) with respect to the corresponding opening (5) is substantially parallel to said rotation axis (A).
The device (1) according to claim 6, characterized in that it comprises a handle (16) for the movement of said stem (13) and of said actuator (6).
The device (1) according to claim 3, characterized in that said base element (10) comprises a block which can be associated with said enclosure (101) and is associated with a coupling plate of the main body (3) of said electric lock (2).
The device (1) according to claim 3 or 8, characterized in that said base element (10) comprises an element (12) for covering any secondary insertion openings provided in the head (4) of said electric lock (2).
A machine (100), comprising a substantially box-like enclosure (101) inside which there is a chamber (102) for the accommodation of moving parts and which is provided with at least one inspection port (103) which is associated with a door (104) that is pivoted about a rotation axis (A) and can move between a closed configuration and an open configuration of said port, characterized in that it comprises a device (1) according to one or more of claims 1-9 which is interposed between said door (104) and said substantially box-like enclosure (101).