Safety method and optoelectronic sensor

p0001The invention relates to a method for securing a hazardous zone of a moving, an engagement point comprising the tool, in particular a vertically downwardly moved the upper tool of a bending press, wherein the hazard area is determined by the extent of the point of engagement of the tool and the stopping distance of the tool along the direction of movement, wherein a optoelectronic sensor is moved together with the tool and monitors the danger zone, and is being triggered on detection of an intrusion into the danger zone a shutdown to halt immediately the tool movement. The invention further relates to a tool having a corresponding opto-electronic sensor.

p0002Background of the Invention is the effort to prevent injury to an operator who works on the moving tool of a machine, for example by the operator to be processed workpieces supplies the tool. In the case of said press brake can - without appropriate security measures - the upper tool a violation or separation of the fingers or hands of the operator cause.

p0003An immediate risk of injury to the operator within the danger zone, which extends from the point of attack of the tool in the direction of movement of the tool. The point of application of the tool includes, for example, a ram or a punch, and it extends, in particular at said press brake, typically along a longitudinal direction, for example along a bending line or cutting edge of the moving tool. The danger zone thus corresponds to a region of space by triggering a shut-off the tool nor distance traveled is determined firstly by the extension of the application zone and the other by the overrun of the tool, ie by.

p0004To secure this danger area, it is known mitzubewegen at least one transmitting device and a receiving device of an optoelectronic sensor with the tool. This sensor monitors by constantly sending and receiving a collimated transmitted light beam, whether an intervention is carried out in the danger zone. If this is detected based on an interruption of the transmitted light beam, a shutdown is triggered, which leads to a continuation of the tool movement.

p0005These known securing methods and sensors can not provide the desired safety in all applications. This is firstly due to the fact that the actually monitored by the sensors known part of the danger zone some distance from the point of attack of the tool takes account of the slowing down path, so that the areas immediately adjacent to the point of attack part of the danger zone is not monitored. Above all, the known monitoring principle is essentially limited to the detection of static interference, ie interventions that already exist at the time of tool movement and can be detected only subsequently, namely as a result of the associated movement of the sensor, the relevant body part of the operator indirectly monitored in the part of the danger zone passes.

p0006From the <patcit id="pcit0001" dnum="WO0067932A"><text>WO-A-0067932</text></patcit> are known a method with the features of the preamble of claim 1 and a tool having the features of the preamble of claim 10.

p0007It is an object of the invention in a moving tool the safety of the operator to increase with respect to all types of possible interventions, without compromising the efficiency of the work process is impaired.

p0008This object is achieved by a method having the features of claim 1.

p0009The object is achieved for a tool with an optoelectronic sensor in a corresponding manner by the features of independent claim 10.

p0010The invention provides additional security against so-called dynamic interventions, ie against interference from the movement of the operator, which take place when the tool movement has already begun. Such dynamic operations are typically carried out from the operator side, particularly obliquely from above or from the front. For example, it often happens that the operator noticed an unexpected slippage of the workpiece to be machined and therefore - regardless of the tool movement already used - nachgreift as an immediate response to the danger zone to perform readjustment. A slippage of the operator's hands from the tool during the movement against a stop device to be pressed workpiece may be a typical dynamic engagement.

p0011In the invention, a backup with respect to such dynamic intervention is performed by an additional monitoring is performed at least within a boundary surface, which - in the end bell forms a kind of protection - at any desired form. The limiting surface has namely with respect to a plane which runs parallel to the tool movement and perpendicular to the extension direction of the point of attack of the tool, a cross-section which extends at least along a circular arc or - extends beyond - in particular in the radial direction.

p0012In the invention, therefore, a monitoring area is provided with a boundary surface, the minimum extent - is defined by a circular arc - in cross section. The center of this circular arc is located - relative to the direction of movement of the tool - in front of the point of attack of the tool. In the case of the vertically moving down the upper tool of a bending press, the center of said circular arc is therefore at a certain distance below the point of attack.

p0013In addition, said arc has a radius which is at least selected so large that the said boundary surface extends in the radial direction at least up to the point of attack of the tool, so that with respect to the direction of movement of the tool no monitoring free gap between the boundary surface and the point of attack of the tool consists.

p0014The radius of said circular arc is also referred to as "monitoring radius".

p0015The invention thus provides improved security of the danger zone to dynamic interventions. Nevertheless - as in the known securing methods and sensors - a non-hazardous, and therefore permissible readjustment of the workpiece to be machined possible, namely by setting the surveillance region or its limiting face is limited with respect to the direction of movement of the tool in space, so that engagement in the monitoring area subsequent space area does not trigger a shutdown.

p0016It is preferred that the boundary surface of the monitored zone is adjacent to the tool. In this way it is guaranteed that no interference between the point of attack of the tool and the monitoring area can be carried out, which is possible with fast dynamic interventions lead to an injury.

p0017Preferably, the boundary surface of the monitored zone - corresponding to the minimum cross-sectional dimension in accordance with a circular arc - convex with respect to the point of application of the tool.

p0018and thus, the boundary surface of the monitored zone - - To create a comprehensive as possible shield against dynamic interference, the said circular arc preferably extends along a segment angle of at least 30 °, in particular of approximately 90 ° or approximately 180 °. These angles refer with regard to the application background of a bending press in particular a substantially vertical monitoring radius as a starting point.

p0019According to this angle to the cross section of the limiting surface may thus have substantially the shape of a quarter circle or a half circle, which can be interrupted by the tool and its point of application. In other words, the monitoring range may have substantially the form of a circular quadrant or a half of the circle.

p0020Furthermore, it is preferred that the boundary surface of the monitored zone extends along the extending direction of the point of attack of the tool. The boundary surface therefore covers, for example, the outer surface of a cylinder segment, especially a quarter or half cylindrical segment.

p0021In a preferred embodiment of the invention, at the boundary surface along the circular arc and / or along the extending direction of the point of attack of the tool to form a substantially closed monitored area, so that any engagement or penetration of the boundary surface can be detected. Such a closed surface can be realized for example by adjacent light beams.

p0022To the shape of the boundary surface of the monitored zone is further to be noted that, while through said circular-arc cross section, the minimum extent is specified basically. However, can be adapted to the shape of the workpiece to be machined, the course. Alternatively or additionally, the boundary surface can be interrupted at one point, on the basis of the structure of the tool intervention in the danger area is anyway inherently excluded.

p0023For the dimensioning of the monitoring area is preferably a residual amount is taken into account, which is always kept at a switching off or stopping the tool. This residual amount is determined generally by the largest part of the body of the operator, which can reach into the danger area under dynamic approach. The necessary residual amount is determined from the defined body part diameter and the allowable pinch. For a finger guard a possible residual amount may for example be about 10 to 14 mm.

p0024can be carried out to the effect that the extension of the consideration of the residual amount in the extension of the monitoring area in the moving direction of the tool - from the point of attack of the tool - is at least the sum of the monitoring radius and the illustrated rest height above. In the case of the vertically moving down the upper tool of a bending this into account so leads to an expansion of the monitoring area down.

p0025The extension of the circular arc radius predetermining minimal monitoring is preferably determined by the response time of the optionally triggered turn-off and / or the maximum speed of approach or entry of the operator, in particular by the product of the response time and maximum approach speed. This ensures that even in the fastest possible intervention of the trip occurs before the intruding into the monitored zone body part of the operator comes into contact with the tool. With such a dimensioning of the monitoring radius, for example, between 20 and 50 mm, in particular, be 24-40 mm.

p0026Alternatively, it can be considered for the design of the monitoring radius, the moving speed of the tool, the response time of the switch-off and / or the stopping of the tool. In particular, the radius can be monitoring the sum of the product of speed of movement and response on the one hand and on the other hand at least overtravel. In this case, the entire braking distance of the tool is taken into account, in particular with regard to an engagement extension in the direction of movement of the tool. With such a dimensioning of the monitoring radius, for example, 6 to 16 mm, be in particular between 10 and 12 mm.

p0027Regarding the position of the center of the circular arc described, this can of the point of attack of the tool in the direction of movement of the tool at least the monitoring radius starting - be spaced - according to one of the above-described mathematical principles.

p0028The monitoring of the monitored zone takes place within the boundary surface, ie with respect to the entire area enclosed by the boundary surface-space volume.

p0029Finally, it should be noted to the movement of the tool, that these in a relatively fast closing movement and a subsequent, slow closing movement may be divided for processing, wherein the workpiece is detected by the tool and processed, in particular formed only in the context of this machining movement.

p0030The transition from the fast closing movement in the slow closing or machining movement is preferably in a switching point, which is programmed or taught by the operator. The objective of the operator is to put this point as close to the workpiece surface. The monitoring and the protection device is preferably from that switching off (so-called muting), since the protection is drawn off by the slow closing or machining movement.

p0031The transmitting device comprises, for example, one or more laser diodes or light-emitting diodes whose emission light beam is expanded by means of a transmitting optical system, so that this transmitter is suitable for monitoring a volume of space. For this purpose, a spatially resolving receiver device is provided, for example CCD or CMOS receiver having a matrix-shaped arrangement of receiving elements.

p0032According to the monitoring function, the transmitting device and / or the receiving device is preferably arranged within said circular arc, wherein this arrangement relates parallel to the tool movement and perpendicular to the extension direction of the point of attack of the tool to the cross section previously mentioned. In this arrangement, the transmitted light beams preferably extend parallel to the direction of the point of application of the tool. To perform the tool movement without hindrance, it is preferable that the transmitting device and / or the receiving device is provided outside the danger area of ​​the tool in a generally known side arrangement.

p0033The transmitting device and the receiving device can be constructed as a so-called active-active system in a direct confrontation, or as active-passive system in which the transmitting device and the receiving device together face a reflector.

p0034The sensor has an evaluation device which is able to detect an interruption of the transmission light on the basis of the received signal of the receiving means and optionally triggers the shutdown process. Of course, this evaluation device need not be moved together with the tool.

p0035Further embodiments of the invention are recited in the dependent claims.

p0036The invention will be exemplified with reference to the drawings; in which:<dl id="dl0001"><dt>FIGS. 1a and 1b</dt><dd>Parts of a bending press in a schematic side view with a further boundary surface of the monitored zone, namely at different times of the mold movement,</dd><dt>Fig. 2, 3 and 4</dt><dd>Parts of a bending press in a schematic side view, each having different boundary faces of the monitored zone, and</dd><dt>FIGS. 5a and 5b</dt><dd>Parts of a known press brake, in a front view and a side view.</dd></dl>

p0037The in <figref idrefs="f0004">FIGS. 5a and 5b</figref> known bending press shown has an upper tool 11 and a lower tool 13. The upper tool 11 can be driven to a vertically downward closing movement 15 to ultimately one between the upper tool 11 and lower tool 13 inserted workpiece, such as a sheet to deform.

p0038The spatial region which extends, starting from the upper tool 11 in the direction of the closing movement 15 up to the lower tool 13, constitutes a danger zone 17 for the operator, which introduce the workpiece between the upper tool 11 and lower tool 13 and adjust there in a certain position and keep to (see. <figref idrefs="f0004">Fig. 5b</figref>).

p0039For the known monitoring the danger zone 17, a transmitting device 19 and receiving means 21 are provided which are mounted in an opposite position on the two sides of the upper tool 11 and accordingly follow the closing movement of 15 (<figref idrefs="f0004">Fig. 5a</figref>). The transmitting device 19 emits a transmitted light beam 23 in the direction of the receiving device 21. The transmitted light beam 23 has a rectangular cross section. He runs inside the danger zone 17, namely with respect to the direction of the closing movement 15 of the upper tool 11 slightly spaced (<figref idrefs="f0004">Fig. 5b</figref>).

p0040If an interruption or attenuation of the received transmitted light is detected, a trip occurs, to stop the closing movement of the upper tool 15 11th Such a shutdown occurs, for example, when the lower part of the danger zone 17 is a hand of the operator and when due to the downward movement 15 of the upper tool 11 and thus the transmitted light beam 23 takes the hand from a certain point in an interruption of the transmitted light beam 23 (static interference) ,

p0041<figref idrefs="f0001">FIGS. 1a and 1b</figref> in contrast, show the surveillance as method and sensor according to the invention.

p0042In <figref idrefs="f0001">FIGS. 1a and 1b</figref> are also an upper tool 11 and a lower die 13, on which a workpiece to be deformed rests 25th The upper tool 11 first performs a quick closing movement 15th The point of attack, so the lower tip of the upper tool 11 is characterized by reference numeral 27th This engagement point 27 extends as a stamp in the viewing direction.

p0043According to the invention a monitoring region 29 is used for securing of the hazardous area of ​​the top tool 11 monitors, in which the <figref idrefs="f0001">FIGS. 1a and 1b</figref> is hatched and by - the in <figref idrefs="f0001">FIGS. 1a and 1b</figref> represented as a solid line - limiting surface 31 is limited.

p0044The boundary surface 31 has on the two sides of the upper tool 11 each have a section in the form of a circular arc 33. The two circular arcs 33 have a common center 35, which is located with respect to the closing movement direction 15 below the point of engagement 27 of the upper tool eleventh The in<figref idrefs="f0001">Fig. 1A</figref> dashed lines radius 37 of the respective circular arc 33 is dimensioned such that the boundary surface 31 well above the point of application 27 connects to the upper tool eleventh

p0045In the area of ​​the top tool 11, the boundary surface 31 has a portion 39 which is adapted to the contour of the upper die 11 so that the monitoring area 29 substantially immediately adjacent to the upper tool eleventh Thus, one end of the respective circular arc 33 extends in the region of the upper tool 11 in a substantially horizontal direction, and the respective other end is substantially vertically downward. The two circular arcs 33 form a semi-circle, the course of which is adapted in the region of the upper die 11 according to the portion 39 of the boundary surface 31 to the shape of the upper tool eleventh

p0046In addition, the monitoring range is 29 extended downwards, namely by the boundary surface 31 two vertical sections 41 having, which adjoin the vertical expiring end of each arc portion 33rd The extension of the monitored zone 29 according to the vertical sections 41 downwards is thus a residual height 43rd

p0047Finally, the monitoring range is 29 bounded below by a horizontal section 45 of the periphery 31st

p0048The monitoring of the danger zone, both within the surveillance area 29 and along the boundary surface 31 is provided by a - not shown - transmitting device and receiving device in a confrontation in a corresponding manner as in <figref idrefs="f0004">Fig. 5a</figref> shown. Accordingly, the monitor area 29 and the boundary surface 31 extending according<figref idrefs="f0001">FIGS. 1a and 1b</figref> in the viewing direction, that is parallel to the direction of the engagement point 27 of the upper tool 11th

p0049The end of the backup process is as follows:

p0050The upper tool 11 is first driven with active surveillance, a comparably fast closing movement 15 vertically downward. Here, the monitoring area 29, its boundary surface 31 and thus also the center 35 of the circular arcs 33 with the upper tool 11 to move with it. Meanwhile, can be done under the surveillance area 29 and below the horizontal portion 45 of the periphery 31 is still an intervention into the danger zone.

p0051However, if an interference in any part of the monitoring area 29 is performed, and if the boundary surface 31 is due to an approach of the operator penetrated at any section 33, 39, 41, 45, this is detected as an interruption of light emitted from the transmission device transmitting light. Then, a shutdown is initiated to stop the upper tool 11 and thereby prevent possible injury to the operator.

p0052Once the upper tool 11 and the monitoring area 29 in the <figref idrefs="f0001">Fig. 1B</figref> Position shown is reached, switching from the fast closing movement 15 to a comparatively slow Berabeitungsbewegung through which the workpiece 25 is to be deformed. Simultaneously, the monitoring is deactivated. The protection of the operator will be realized by the slow closing or machining movement.

p0053The backup method and the sensor according to the invention thus offer over the known securing the danger zone in accordance with the <figref idrefs="f0004">FIGS. 5a and 5b</figref> the advantage of a security against dynamic interventions is ensured by the operator. If namely, takes place during the fast closing movement 15 intervention in the danger area, for example, by a so-called Nachgreifen, is ensured by the radial extension of the monitored zone 29 along the circular arcs 33 to the radius 37 that timely switching off the movement of the top tool 11 takes place.

p0054With regard to intervention, obliquely from above or from the side of radius 37 is, for example, at least so large that it corresponds to the product of the response time of the switch-off and the maximum approach speed of the operator.

p0055<figref idrefs="f0002 f0003">FIGS. 2-4</figref> show respective side and cross sectional views of further embodiments of a monitoring.

p0056<figref idrefs="f0002">Fig. 3</figref> and <figref idrefs="f0003">4</figref> show embodiment of the invention there is no monitoring for the entire area enclosed by the boundary surface area volume occurs.

p0057In the embodiment of <figref idrefs="f0002">FIG. 2</figref> is merely a backup provided on the operator side facing the upper die 11 so that the monitoring area 29 in the cross sectional view shown occupies substantially a quarter of a circular surface or in relation to its spatial extent comprises fourth cylinder segment.

p0058In the example of <figref idrefs="f0002">FIG. 2</figref> the boundary surface 31 of the monitored zone 29 is not specifically monitored, as is expressed by the dashed representation of the boundary face 31st However, it is also possible here to the boundary surface to monitor the 31st

p0059In the embodiment of <figref idrefs="f0002">Fig. 3</figref> is monitored, for example, along the boundary surface 31, ie, along the semicircular arc 33, the vertical portions 41 and the horizontal portion 45th

p0060The center 35 of the arc 33 is located exactly at the radius 37 of the arc 33 below the point of application 27 here.

p0061is for the lower part of the monitoring area 29 - similar to the embodiment according to <figref idrefs="f0001">FIGS. 1a and 1b</figref> - A minimal residual height 43 provided.

p0062<figref idrefs="f0003">Fig. 4</figref> shows the minimum required dimension of the boundary surface 31, which is required to achieve a safeguard against over interference from the side and obliquely from above.

p0063Here a monitoring occurs only along the circular arc 33 (solid line) or along the extension of the arc 33 in the viewing direction. The circular arc 33 extends over at least 30 °, the bisector of the circular arc 33 and of the corresponding circle segment forms an angle of approximately 45 ° to the horizontal. The boundary surface 31 thus extends flat convex.

p0064The center 35 of the arc 33 is arranged around the radius 37 just below the point of attack 27th

p0065The embodiments according to <figref idrefs="f0001">FIG. 1a, 1b</figref>. <figref idrefs="f0002">2, 3</figref> and <figref idrefs="f0003">4</figref> it should be noted that the extension, in particular the radial extent of the monitored zone 29 and the boundary surface 31 can go via the monitoring minimum required radius. So corresponds to the<figref idrefs="f0001">FIGS. 1a and 1b</figref> Radius shown 37 of arcs 33 is not necessarily the minimum required monitoring radius, but may go beyond this, to ensure, for example, a complete enclosure of the underside of the upper tool 11th It is also possible that the boundary surface 31 in cross section has not necessarily a circular arc shape, but for example, a rectangular course.

LIST OF REFERENCE NUMBERS

p0066<dl id="dl0002" compact="compact"><dt>11</dt><dd>upper tool</dd><dt>13</dt><dd>lower tool</dd><dt>15</dt><dd>closing movement</dd><dt>17</dt><dd>danger area</dd><dt>19</dt><dd>transmitting device</dd><dt>21</dt><dd>receiver</dd><dt>23</dt><dd>Sending light beams</dd><dt>25</dt><dd>workpiece </dd><dt>27</dt><dd>attack site</dd><dt>29</dt><dd>monitoring area</dd><dt>31</dt><dd>boundary surface</dd><dt>33</dt><dd>arc</dd><dt>35</dt><dd>Focus</dd><dt>37</dt><dd>Radius of the arc</dd><dt>39</dt><dd>Portion of the boundary surface in the region of the upper tool</dd><dt>41</dt><dd>Vertical section of the boundary surface</dd><dt>43</dt><dd>rest height</dd><dt>45</dt><dd>Horizontal portion of the periphery</dd></dl>