Abstract:
The invention relates to a machine tool monitoring device with an identification unity for identifying the operating situation of a machine tool. According to the invention, the machine tool monitoring device has at least one projection unit for defining at least one region to be monitored.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a machine tool monitoring device according to the preamble of claim  1 . 
       BACKGROUND  
       [0002]    A machine tool monitoring device with an identification unit for identifying the operating situation of a machine tool is already known. 
       SUMMARY 
       [0003]    The invention relates to a machine tool monitoring device with an identification unit for identifying the operating situation of a machine tool. 
         [0004]    According to the invention, the machine tool monitoring device has at least one projection unit for defining at least one region to be monitored. By the term “projection unit”, particularly a unit is to be understood in this context, which projects regions, respectively zones, in particular regions to be monitored, onto an object, preferably on a workpiece, and thereby preferably makes said regions identifiable, especially optically visible, to an operator of the device. In so doing, the regions, respectively zones, are arranged around a tool and consequently contribute to the safety of an operator during the operation of the machine tool. Furthermore, by the term “region to be monitored” particularly a region is understood, which is arranged around a tool and warns the operator of a danger due to being in close proximity to said machine tool; and/or an operation, respectively actuation, of the machine tool is decreased, respectively interrupted, in said region due to the presence of human tissue. By the term “operating situation”, in particular a situation of an operation, respectively an actuation of the machine tool, respectively of a tool of the machine tool, is to hereby be understood. In so doing, a risk of injury to an operator as, for example, cutting off a finger, respectively a hand, can at least be reduced, respectively prevented. Preferably the operator is made aware of an impending danger by an optical definition of the regions to be monitored. 
         [0005]    If the projection unit defines at least two regions to be monitored for the monitoring of an operating process of the machine tool, an advantageous graduation of the regions to be monitored into various safety regions can thereby be achieved. By the term “operating process of the machine tool”, in particular an operation especially like sawing, cutting etc. by the machine tool can thereby be understood. 
         [0006]    According to the invention, the projection unit furthermore has an optical projection unit, whereby an advantageous defining, in particular an optical defining, of the regions to be monitored can be achieved; and in so doing, an advantageous transmission of said regions to the operator can likewise be achieved. 
         [0007]    According to the invention, the machine tool monitoring device additionally has an identification unit for identifying human or animal tissue and or a workpiece, whereby an additional safety function can be achieved for an operator and/or further objects of a human or animal nature. For example, if the identification occurs in the region of the tool, a warning would thereby be transmitted to the operator. Moreover, an advantageous discrimination between the workpiece and a hand of the operator can thereby be made possible. 
         [0008]    In an additional configuration of the invention, it is proposed that the identification unit defines at least two regions to be monitored for the monitoring of an operating process of the machine tool, whereby advantageous, different safety stages of the machine tool monitoring device can be achieved. The regions to be monitored by the projection unit and the regions to be monitored by the identification unit advantageously at least partially overlap. 
         [0009]    A particularly good visibility of the regions to be monitored by the identification unit can be achieved for an operator of the machine tool if the regions to be monitored by the projection unit define the regions to be monitored by the identification unit, in particular optically define. 
         [0010]    A particularly high safety standard for an operator can be advantageously achieved and/or an impending danger to an operator can advantageously be made visible if at least one region to be monitored by the projection unit has an optical and/or visual appearance, which changes if human or animal tissue and/or a workpiece move into the region to be monitored. Moreover, this can cause an operator to unlearn a careless work practice, as, for example, repeatedly allowing a hand to rest in one of the regions being monitored. 
         [0011]    According to the invention, a different mode of operation of the machine tool is furthermore assigned in each case to the regions being monitored when a human and/or animal tissue is identified. In so doing, a mode of operation of the machine tool can be adapted to a dangerous situation, which is immediately impending, and thereby a risk potential can be advantageously reduced for an operator during the operation of the hand-held machine tool. 
         [0012]    If a warning mode is assigned to at least one of the regions to be monitored, an advantageous safety measure can be achieved for an operator by said operator being made aware that a body part of his is in a dangerous situation, which is indicated by a proximity to the tool of the machine tool. 
         [0013]    The safety of the operator can be advantageously improved if the identification unit concurrently with a machine tool drive unit, which is provided to actuate the machine tool, is equipped to slow down the machine tool drive in the warning mode, and/or a safety cut-out of the machine tool is assigned to at least one of the regions to be monitored. In this context of a “safety cut-out”, in particular an at least partially automatic cut-out and a fully automatic cut-out, which is especially advantageous, are to be understood, whereby a termination of the drive, respectively the operation of the machine tool occurs as soon as human or animal tissue is located in the region to be monitored, which is assigned to the safety cut-out. For this purpose, provision is preferably made for the identification unit to determine a position and/or speed, in particular to determine a position and/or speed of human or animal tissue and/or a workpiece by, for example, determining a dielectric constants In so doing, an operation of a saw can be especially advantageously stopped when the workpiece is missing. 
         [0014]    In a preferred embodiment of the invention, it is proposed that the machine tool monitoring device, in particular the identification unit, has at least one UWB radar sensor (ultra-wideband radar sensor). A high degree of information density and thereby an effective monitoring can be achieved with the utilization of ultra-wideband signals. By the term “UWB radar sensor”, respectively “ultra-wideband radar sensor”, in particular a radar sensor is to be understood in this context, by which an ultra-wideband radar signal can be produced, transmitted, received and/or evaluated. Especially an electromagnetic signal, which has a useful frequency range with a medium frequency in the frequency range of 1 GHz to 15 GHz and a frequency band width of at least 500 MHz, is understood by the term “ultra-wideband (or UWB) radar signal”. 
         [0015]    An especially effective identification can be achieved if the machine tool monitoring device, in particular the identification unit, has an antenna array. By the term “antenna array”, a group of a plurality of antennas, which are different from each other, is to be understood in this context, said antennas being fed during the operation with a signal to be transmitted by means of a common signal production unit. The antenna array advantageously has at least one ultra-wideband radar antenna. 
         [0016]    Accuracy when identifying the operating situation can be increased if the antenna array is configured as a phase-variable antenna array. By the term “phase-variable” antenna array, in particular an antenna array is to be understood in this context, to which at least one phase shifting means is assigned, which is provided for changing at least one relative phasing between two signals, which are emitted from different antennas of the antenna array. In an additional configuration of the invention, an infrared sensor, which advantageously detects a human or animal tissue by means of temperature using a reflection spectrum, a camera, which preferably possesses an intelligent object detection, and/or additional detection, respectively identification, elements can be alternatively employed instead of a UWB radar sensor and an antenna array. 
         [0017]    The identification unit advantageously comprises a computation unit, which is provided for the purpose of identifying an operating situation by means of an evaluation of parameters, which is based on fuzzy and/or neuronal logic. A large and complex amount of information can be quickly evaluated by the computation unit based on the acquired signal with the aid of fuzzy logic. Fuzzy logic represents in particular logic, which assigns a probability value in a range between 0 (false) and 1 (true) to the occurrence of a certain event. Advantageous self-learning functions of the machine tool monitoring device can be achieved by neuronal logic. 
         [0018]    According to the invention, the identification unit has a data bank, wherein an operating situation is assigned to a set of parameters, in an advantageous modification. An especially rapid identification process of an operating situation can thereby be achieved by examining a correlation between the acquired parameters and an operating situation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Additional advantages result from the following description of the drawing. Examples of embodiment of the invention are depicted in the drawing. The drawing, the description and the claims contain numerous characteristics in combination. The specialist will also advantageously consider the characteristics as individual entities and consolidate them into meaningful, further combinations. 
           [0020]    The following are shown: 
           [0021]      FIG. 1  is a machine tool with a machine tool monitoring device according to the invention in a schematic depiction, 
           [0022]      FIG. 2  is a partial region of the machine tool with the machine tool monitoring device in a perspective view, 
           [0023]      FIG. 3  is a partial region of the machine tool with the identification unit in a schematic depiction, and 
           [0024]      FIG. 4  is a partial region of an alternative machine tool with a machine tool monitoring device in a perspective view. 
       
    
    
     DETAILED DESCRIPTION  
       [0025]    A machine tool  14  composed of a circular table saw is schematically depicted in  FIG. 1 . The circular table saw comprises a tool  30  composed of a circular saw blade and a sawing table  42 , wherein the tool  30  is rotationally fixed around a rotation axis  44 . An actuation of the tool  30  results by means of a machine tool drive unit  28  of the machine tool  14 . In addition the machine tool  14  comprises a protection cover  46 , which encloses the tool  30  in a circumferential direction to said tool  30  in a region, which projects out of the machine tool  14  for the purpose of machining objects, respectively workpieces  50 . Furthermore, the machine tool  14  has a machine tool monitoring device  10  with a projection unit  16  and an identification unit  12 , which are provided to protect an operator from injury during the operation of the machine tool  14 . The identification unit  12  is provided for an identification of an operating situation, in particular a mode of operation, of the machine tool  14  and for a detection of human and/or animal tissue  26  and/or the workpiece  50 , as, for example, a hand of the operator, and is therefore disposed beneath a sawing table plate  52 . In order to perform said identification, the identification unit  12  has a computation unit  38  and a data bank  40 . The projection unit  16  is provided to project regions to be monitored  18 ,  20  onto the workpiece  50  to be machined during the operation of the machine tool  14 . For this purpose, the projection unit  16  is disposed in a front region  54  by means of a holding device  56  ( FIG. 2 ), which is configured separate from the protection cover  46  and is covered by said cover  46 . In so doing, a protective function of the projection unit  16  is guaranteed even if the protection cover  46  has been removed. It is also basically conceivable for the projection unit  16  to also be directly integrated into, respectively disposed in, the protection cover  46 . In so doing, the projection unit  16  consists of an optical projection unit  16 . 
         [0026]      FIG. 2  shows a partial region of the machine tool  14 , which is composed of the circular table saw, with the tool  30 . The holding device  56  has a holding arm  58 , whereupon a retaining element  64  is disposed on a side facing a front region  60  of the tool  32 . The front region  60  of the tool  30  is defined as the region of the tool  30 , which is in contact with the workpiece  50  to be machined during an operating process. The retaining element  64  is provided for the disposal of the optical projection unit  16 . Two regions to be monitored are defined  18 ,  20  using the projection unit  16 , the two regions to be monitored  18 ,  20  being projected onto a workpiece surface  66 , respectively a sawing table surface  68 . The two regions to be monitored  18 ,  20  by the projection unit  16  are provided for the purpose of marking a danger zone, respectively two different danger zones, so that said zone(s) is optically visible to an operator during the operation of the machine tool  14 . The first danger zone, respectively the first region to be monitored  18 , is thereby disposed directly around the tool  30 , respectively in the contact region of the tool  30  with the workpiece  50 . The second danger zone, respectively the second region to be monitored  20 , is disposed around the tool  30  and the first region to be monitored  18  at a greater distance to the tool  30  than the first region to be monitored  18 . 
         [0027]    The two regions to be monitored  18 ,  20  are radiated by the projection unit  16  with diverse, colored light for an optical discrimination between said regions  18 ,  20 . For this purpose, the projection unit  16  has a laser unit  70 , which projects laser light of a certain color onto each of the two regions to be monitored  18 ,  20 ; and in so doing, the laser light color of the first region to be monitored  18  varies from the laser light color of the second region to be monitored  20  so that an optical discriminability of the two regions to be monitored  18 ,  20  is provided. The colors of the laser light can furthermore be changed as a function of a color of the workpiece surface  66  by the operator of the machine tool  14  via an unspecified input unit. Moreover, the projection unit  16 , respectively the laser unit  70 , is provided for the purpose of changing an optical and/or visual appearance of the second region to be monitored  20  as soon as human tissue  26 , especially a hand of the operator, or animal tissue  26  and/or the workpiece  50  moves into said region to be monitored  20 . The change in the optical and/or visual appearance results from a change in the laser light color and/or a change in the laser light intensity, as, for example, a blinking of the laser light and/or additional light signals. Further optical and/or acoustic warning signals by the projection unit  16  as an alternative or in addition to the changes, which are shown, are conceivable at all times. 
         [0028]    A detection of human or animal tissue  26  results by means of the identification unit  12  ( FIG. 3 ). The identification unit  12  has two regions to be monitored  22 ,  24  for this purpose, which essentially correlate to the two regions to be monitored  18 ,  20  by the projection unit  16  so that the regions to be monitored  22 ,  24  by the identification unit  12  are optically marked off by the regions to be monitored  18 ,  20  by the projection unit  16  for an operator of the machine tool  14 . Furthermore, provision is made for the two regions to be monitored  22 ,  24  to monitor an operating process, as, for example, sawing, of the machine tool  14 . The identification unit  12  has a phase-variable antenna array  34  with a plurality of UWB radar sensors  32 ,  72 , which are distributed onto both of the regions to be monitored  18 ,  20 . The UWB radar sensors  32 ,  72  comprise in each case a UWB radar antenna  36 ,  74 , which is provided for emitting, respectively receiving, an ultra-wideband radar signal. During the operation of the machine tool, provision is made for the identification unit  12  to determine the position of human or animal tissue  26  by means of the phase-variable antenna array  34 , respectively the UWB radar sensors  32 ,  72 . In an additional configuration of the invention, a determination of the speed of human or animal tissue  26 , which is moving itself, as, for example, the movement of the hand of the operator, and/or of the workpiece  50  using the identification unit  12  is also furthermore alternatively or additionally conceivable. 
         [0029]    A different mode of operation of the machine tool  14  is assigned in each case to the two regions to be monitored  22 ,  24  by the identification unit  12 , which are equipped with UWB radar sensors  32 ,  72 , as soon as a hand of the operator is located in one of the regions to be monitored  22 ,  24  by the identification unit  12 . A warning mode of the machine tool  14  is thereby assigned to the second region to be monitored  24 . Besides an output of an optical warning signal in the second region to be monitored  20  by the projection unit  16  by means of the projection unit  16 , respectively the laser unit  70 , in the warning mode of the machine tool  14 , provision is made for the identification unit  12  together with the machine tool drive unit  28  to reduce the rotational speed of the tool  30 . If the hand of the operator is located in the first region to be monitored  22  and consequently said hand is in the immediate proximity of the circular saw blade, the machine tool  14 , respectively an operation of the circular saw blade, is automatically shutdown by the identification unit  12 . In so doing, the hand situated in one of the regions to be monitored  22 ,  24  is ascertained in the accordant region to be monitored  22 ,  24  by means of the antenna array  34 , respectively the UWB radar sensors  32 ,  72  concurrently with the computation unit  38 , by means of which an evaluation of sensed data, respectively parameters of the UWB radar sensor  32 ,  72 , occurs. An evaluation by the computation unit thereby results via fuzzy, respectively neuronal, logic. As soon as the hand is detected within one of the regions to be monitored  22 ,  24 , the computation unit selects appropriate parameters for the warning mode, which is assigned to the detected operating situation, and sends said parameters to the machine tool drive unit  28  and/or to the projection unit  16  via an unspecified data line. The parameters are stored for this purpose in the data bank  40 , the computation unit  38  selecting the parameter from a set of parameters, to which in each case an operating situation is assigned. Using the parameters selected by the computation unit  38 , the projection unit  16  is induced to output warning signals in the second region to be monitored  20  by the projection unit  16 : respectively the rotational speed of the circular saw blade, respectively a shutdown of a drive of the circular saw blade together with the machine tool drive unit  28 , is set. 
         [0030]    An alternative example of embodiment of a machine tool  14  to  FIGS. 1 to 3  is depicted in  FIG. 4 . Components, characteristics and functions, which essentially remain the same, are basically denoted with the same reference numerals. In order to distinguish between the examples of embodiment, the letter “a” is however added to the reference numerals of the example of embodiment in  FIG. 4 . The following description essentially limits itself to the differences vis-à-vis the example of embodiment in  FIGS. 1 to 3 ; and in so doing, reference can be made to the description of the example of embodiment in  FIGS. 1 to 3  with respect to components, characteristics and functions, which remain the same. 
         [0031]    The machine tool  14   a  comprises a panel sawing machine. The panel sawing machine has a tool  30   a  with a protection cover  46   a,  which are disposed so that they can be tilted around a tilting axis in relation to a sawing table  42   a.  Said tool  30   a  is also equipped with a machine tool monitoring device  10   a.  For this reason, a tool holding device  76   a  of the machine tool  14   a  has a retainer rail  78   a,  wherein the tool  30   a  together with the protection cover  46   a  can be tilted, and two holding arms  80   a,  which are provided for a securing of the position of the tool  30   a  and the protection cover  46   a  and are disposed on both sides of the tool  30   a.  The holding arms  80   a  are in each case disposed on the retainer rail  78   a  and in the region of a rotation axis  82   a  of the tool  30   a  at the protection cover  46   a.    
         [0032]    Furthermore, the holding arms  80   a  have in each case a retaining element  64   a  on an end region  84   a,  which faces away from the retainer rail  78   a,  for the disposing of the projection unit  16   a.  A projection, respectively marking off of regions to be monitored  18   a,    20   a  by the projection unit  16   a,  respectively a detection of human tissue within the regions to be monitored  22   a,    24   a  by an identification unit  12   a  of the machine tool monitoring device  10   a,  takes place analogously to the description of the  FIGS. 1 to 3 .