Abstract:
A machine tool, in particular in a handheld configuration, that is equipped with tools for a sensory detection of a trajectory that serves as a guideline and is detected in characteristic values and read in, alternatively to a programmed trajectory. The characteristic values that are on a side of the machine tool are converted into control signals for a working line that is tracked mark-free.

Description:
[0001]    This application claims benefit of Ser. No. 10 2008 041 088.8, filed Aug. 7, 2008 in Germany and which application is incorporated herein by reference. To the extent appropriate, a claim of priority is made to the above disclosed applications. 
       TECHNICAL FIELD 
       [0002]    The invention concerns a procedure for operating a machine tool, in particular a handheld machine tool, with devices for a sensory detection of reference characteristics that are on the side of the work piece and for an arithmetical conversion of characteristic values that correspond with these characteristics into control signals, which serve for a guidance of the machine tool across from a corresponding work piece. The invention furthermore concerns also a machine tool that has to be operated according to the procedure. 
       BACKGROUND 
       [0003]    At machine tool, in particular handheld machine tools, which work for a material removal, especially jig- or circular saws as well as finger rotary cultivators, the view of the user is often restricted to the field of work or the working tool that is on the side of the work piece—and marks that might be there—due to handling, construction type and/or function. That complicates the working and can also impair the working results. Therefore it is often worked with auxiliary devices, thus for example with illuminating devices in order to improve the visibility at least in the immediate field of work. Furthermore also with observing devices that shall enable an indirect observation of the field of work. 
         [0004]    For such machine tools it is also worked with auxiliary devices, which should make the tracking of a desired working line easier, even if it is can only be seen insufficiently due to dirt or due to the covering of the machine tool. Thereby the guidance of the machine tool takes place along a trajectory as guideline that is parallel to the desired working line and shifted sideways. A guide shoe, which is overhanging sideways to the machine tool and which is arranged and applied at an adjustable radial-arm that is opposed to the machine tool and which can be shifted along the guideline serves as an auxiliary device. 
         [0005]    By adjusting the guide shoe across from the machine tool, thus by changing the distance that has been bridged over the radial-arm between the guide shoe and the machine tool, parallel working lines that are located shifted to a guideline can be driven. But this is always connected with a corresponding adjustment work. 
       SUMMARY 
       [0006]    The invention is based on the task to create better possibilities of guidance of a machine tool on a desired working line for the user, which follows a guideline, as well as depending on the configuration of the machine tool if necessary to support the user also in its guidance of the machine tool that is oriented by the guideline on such a working line. 
         [0007]    One aspect of the invention relates to a trajectory that is preset for the machine tool on the side of the work piece. The trajectory is detected by its characteristic values and is read in on the side of the machine. By the control signals for the working tool that correspond with these characteristic values, a working line that has to be driven and that corresponds with the read-in trajectory is provided mark-free. 
         [0008]    The tools, which serve the sensory detection of the reference characteristics that are on the surface and describe the trajectory, are hereby not used to read in the trajectory, but moreover also for the orientation of the machine tool towards characteristics that are on the side of the work piece when driving along the working line that is provided arithmetically and that corresponds with the read-in trajectory. Thereby the procedure according to the invention can be implemented at least without an additional significant effort on the side of the machine, but simultaneously track a once read-in thus detected trajectory several times, without additional adjustment works, because a noticeable illustration of the working line, for example by marks, is not necessary. 
         [0009]    The same applies basically also when a trajectory serves as a guideline that is not driven along and read-in with the aid of a trajectory on the side of the work piece, but instead is provided programmed, whereby it is in the range of the invention to configure the machine tool in such a way that it can be work on the basis of a trajectory that is either read in or programmed. 
         [0010]    When reading in the trajectory that creates the guideline it is detected at least in the course and direction towards the work piece, if the user should only be supported passively when driving along a corresponding working line, namely by corresponding hints as for example signal-beams and/or display illustrations of the corresponding section of the working line that has to be driven along and/or direction hints. Such hints can also be the displaying of the nominal direction and deviations hereto in color. 
         [0011]    If the user is actively supported at the guiding of the machine tool in particular at so-called semi-automatic systems, thus especially by an orientation of the working tool of the machine tool towards the working line that has to be driven along by a corresponding changing of the rotational position towards the machine tool, a trajectory that has been read in is not only detected according to its course and orientation, but moreover also the rotational position of the tool to the machine tool—corresponding hereto—is provided. The same applies also with regard to trajectories that are programmed. 
         [0012]    The sensory tools for detecting a trajectory that serves as a guideline as well as for guiding the machine tool along a mark-free working line that has to be driven along, each oriented at reference characteristics on the side of the work piece, are usefully created by so-called speed-over-ground or mouse sensors, which allow to detect the speed, the orientation of the machine and the type of track, thus its straight or cricket course. 
         [0013]    Independent of the guiding of the machine tool only by the user or semi-autonomously, thus at only direction oriented supporting of the machine tool by the user, the danger exists in particular at irregularities in the structure of the work piece and/or working lines with narrow curve radii, that with regard to an advance speed the working speed of the tool is big and that the tool gets therefore too hot, so that the work piece “burns out” in the area of the processing position while sawing at the sawing position. In order to face that an adaptive adjustment of the working speed of the tool to the advance speed is provided according to the invention for example by changing the number of strokes or the rotational speed. 
         [0014]    At machine tools, in particular at handheld machine tools such as jig or circular saws, it is generally a problem to meet the starting point on the side of the work piece for a desired working line that has to be driven along and additionally to orient the machine tool or the tool according to the direction of the course of the working line based on the starting point, in order to achieve a waste-free operation. This is particularly important if a trajectory is provided for the machine tool that is read in or programmed and based on that a working line has to be driven along mark-free, for whose position and orientation towards the work piece the position and orientation in the starting point is absolutely determining. 
         [0015]    With regard to this determination a detection of the reference characteristics on the side of the work piece in the area of the starting point to the work piece is provided according to the invention and furthermore the position of the machine tool to the work piece with regard to a reference position that is given by the reference characteristics is determined. This reference position is detected in its position to the working line that has to be driven along, so that by a display of the deviation a corresponding alternating orientation can takes place by the user or analogously on the side of the machine tool by an orienting control of the working tool. 
         [0016]    By such an orientation it is achieved and established that by reading in or programming preset trajectories can be exactly tracked as working lines not only in its alignment, but also in a desired position and/or orientation towards each other if necessary, so for example with a course that is parallel to each other; all this in a user-guided as well as only user-supported semi-autonomous operation of the machine tool. 
         [0017]    Such a procedure according to the invention is also useful at a guidance of a tool that only takes place on the side of the user along a working line that has to be tracked by default marks based on its starting point, but especially when such a working line is provided mark-free on the part of the machine tool, be it by reading in or programming, because in a semi-autonomous operation ultimately there are barely any correction possibilities on the part of the user by changing his guiding behavior. 
         [0018]    The invention furthermore concerns a machine tool, in particular a handheld machine tool, which enables a previously described procedure and which provides a working area for a working tool, which has to be positioned at a work piece. Furthermore with tools for a sensory detection of reference characteristics on the side of the work piece that are given in the area of the working tool, whereby a arithmetic and control unit for processing the sensory detected reference characteristics as well as for converting them into characteristic values and for adjusting with characteristics values is provided, which describe a default trajectory. By control signals that correspond with these characteristic values the orientation of the machine tool and/or the working tool towards a virtual working line that corresponds with the trajectory and that has to be tracked on the side of the work piece is carried out, and/or hints for guiding the machine tool on this working line are controlled for the user. This takes for example place in the form of display illustrations, or by orienting corresponding signal-aids, in particular optical signals-aids in the form of signals-beams. 
         [0019]    The tools that serve for the sensory detection of reference characteristics are created as optical tools in particular by sensors, especially mouse sensors, which are arranged in working direction upstream to the working tool and pointed at the work piece. Instead of such mouse sensors, by which the rotational direction of the machine tool, its advance speed as well as the course of the working line as a straight or curve can be detected, also mechanical sensors, such as friction wheels, friction rolls or balls can be used. The latter in particular in connection with sensors that are construed in the form of a camera, by which information can be won that corresponds by a picture comparison, that has to be processed by the arithmetic and control unit and that has to be converted into characteristic values as well as control signals. 
         [0020]    Particularly advantageous is the operation of the machine tool according to the invention in the form of jigsaws with an adjustable saw blade that is driven stroke-movably and that can be rotated around its longitudinal axis, whose rotational position is oriented at the corresponding working line by an actuator that belongs to the control and arithmetic unit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Further details and characteristics of the invention arise from the claims. Furthermore the invention is explained in the following with the aid of an embodiment. 
           [0022]    It is shown: 
           [0023]      FIG. 1  is a jigsaw in a perspective illustration as an example for a machine tool according to the invention, which provides a saw blade being a jig saw, which has to be operated semi-autonomously and which can be rotated around its longitudinal axis and adjusted in its rotational position by an actuator, and which meshes into a work piece in the illustration, on which the jig saw is positioned, 
           [0024]      FIG. 2  is a schematized illustration of a top view on the working area of the base plate of the jig saw that has been infiltrated by the saw blade at the indication of a working line for the saw blade, and 
           [0025]      FIG. 3  is an illustration that is similar to  FIG. 2 , in which the base plate of the machine tool is illustrated while approaching a work piece, for explaining the positioning of the machine tool at a work piece with an orientation towards a working line, which has to be driven along the work piece and which is based on a starting point for the tool. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]      FIG. 1  illustrates a handheld machine tool  1  in the form of a jigsaw  2 , which provides a housing  3  and which is adjustably supported by a base plate  4  on a work piece  5 . In working direction  6  in the front area of the jigsaw  2  it provides a saw blade  8  as a working tool  7 . It meshes in working operation into the work piece  5 . 
         [0027]    The jigsaw  2  provides furthermore a field of vision  10  on the side of the user, which spreads at least over the range of the working area  9  that is determined by the saw blade  8 , and as illustrated, which reaches out over it in working direction  6 , in order to provide the user with an optimal overview over the working conditions. The working area  9  and the field of vision  10  are illustrated as section that is provided in the base plate  4 , so that with regard to the working tool  7  corresponding with the size of the field of vision  10  a significant protrusion of the base plate  4  beyond the saw blade  8  results. 
         [0028]    The housing  3  of the jigsaw  2  provides a strap-like handle  11  in upwards direction opposed to the base plate  4  that is supported noticeably and that goes around a swiveling axis in working direction  6 , whose grip handle  12  spans in working direction  6  and arrives in the front at the front wall area  13  of the housing  3 . Upwards it merges into a guide knob  14 . In the area of the handle  11  a switch arrangement  15  is provided gripping under the grip handle  12 , by which the machine tool  1  can be switched on and off. Different operating modes of the jigsaw  2  can be adjusted over the switching device  16  that is provided on the longitudinal side of the housing  3 . 
         [0029]    The front wall area  13  of the housing  3  is layered offset contrary to the working direction  6  and running downwards in the direction of the base plate  4 . The thereby originating step  17  covers the tool entrance  18  for the saw blade  8 , which is driven stroke-movably according to the embodiment of the machine tool  1  as an electrically operated machine and in the direction of the arrow  19 . 
         [0030]    A first operating mode is the regulation work operation, at which the saw blade  8  that is pointed torque-proof in working direction  6  is operated only in direction of stroke (arrow  19 ). 
         [0031]    A further operating mode is the so-called pendulum stroke operation, at which the saw blade  8  that is overlaid to the stroke movement in the direction of the arrow  19  can be swiveled around a not shown swivel axis that runs transversely to the saw blade level. The actuator  20  that is provided for this purpose is partially illustrated. 
         [0032]    In a third operating mode, illustrated by the arrow  21 , the saw blade  8  can be swiveled in addition to the stroke movement (arrow  19 ) around a rotational axis  22  that runs in the direction of its longitudinal axis. The saw blade  8  can thereby be adjusted from its straight position, corresponding with a zero angle to the longitudinal axis  25  of the jigsaw  2 , into working directions that are angled to the longitudinal axis  25 . The jigsaw  2  can thereby be used as so-called scrolling jigsaw and can be operated at a correspondingly controlled adjustment as semi-autonomous jigsaw  2 . That means, that the user that is holding the jigsaw  2  basically takes over only the advance that is roughly pointed at the corresponding working direction  6 , and supports reaction forces that result from the working operation, but that the exact positioning of the jigsaw  2  that is pointed at a working line  24  and corresponding with it takes place by a rotational adjustment of the saw blade  8 . 
         [0033]    The jigsaw  2  is furthermore provided with tools  27  for a sensory detection of reference characteristics  28  on the side of the work piece, as they are shown in  FIG. 2 and 3  as characteristics that can be optically noticed at the work piece  5 , for example in the form of grains  32  or even work piece edges  39 . A camera  29  is indicated as a tool  27  for the sensory detection in the transition that is created by step  17 , but the corresponding area qualifies also for other sensor arrangements, as in particular line sensors. It is furthermore preferred to provide an illuminating arrangement  30  or also a signal-beamer as an advantage, if desired, the illuminating arrangement for improving the viewing conditions in the working area  9  and/or in the field of vision  10 , the signal-beamer as an optical orientation aid for a user in the direction of the machine tool  1  towards a working line  24 . 
         [0034]    Further tools  27  for the sensory detection of reference characteristics  28  on the side of the work piece are mouse sensors  31  that are arranged on the front side of the base plate  4  on both sides of the longitudinal axis  25 . 
         [0035]    It is furthermore schematically indicated in  FIG. 1  that the machine tool  1  is equipped with control tools  34 , thus in particular with an arithmetic unit  35  and a control unit  36 , preferred with a subordinate adjusting unit, which comprises an actuator for adjusting the rotational position of the saw blade  8 . A furthermore provided display field  37  serves in particular for providing the user with hints for the guidance of the machine tool, but can also be used for warning notices and such alike. The display field  37  is arranged in the front wall area  13 , preferably above step  17  and overhanging in the opposite direction to it, so that is located in the immediate field of vision of the user. 
         [0036]    According to the invention the tools  27  for the sensory detection are partially used under different aspects, thus for detecting a trajectory  41  ( FIG. 3 ) that is tracked by the machine tool  1  at a work piece on the one hand, and corresponding with that, for orienting by detecting characteristics on the side of the work piece as reference characteristics ( 28 ) on the other hand, if a desired, unmarked working line  24  that is on the side of the work piece shall be driven along, which corresponds with the read-in trajectory  41 . 
         [0037]    If it is worked with a camera  29  the required movement data can be determined by an image comparison, if it is worked with mouse sensors  31  the corresponding movement data results from the detected reference characteristics of the work piece surface, thus for example grains  32  or edges  39 . 
         [0038]    Instead of the detection of a tracked trajectory and its storage, in order to be able to use it subsequently as guideline for a working line  24  that has to be driven along, the guideline of corresponding movement data for a working line  24  that has to be driven along can also take place by an arithmetical way and be provided programmed. 
         [0039]    With the tools  27  for a sensory detection the position of a machine tool  1 , in particular a jigsaw  2  to a work piece  5 , at which the jigsaw  2  should be positioned, can also be detected, as it is indicated in  FIG. 3 .  FIG. 3  illustrates this situation and due to simplicity reasons only the base plate  4  of the jigsaw  2  is shown in an illustration that is analogous to  FIG. 2 , positioned opposed to the work piece  5 , so that the base plate  4  is initially positioned with its front side  38  contrary to the edge  39  of the work piece  5 . If the jigsaw  2  moves along in working direction  6 , the base plate  4  runs towards the work piece  5  and thus the edge  39  and subsequently also other reference characteristics—such as the grain  31 —into the observation area of the sensory tools  27 , in particular the mouse sensors  31  at first. But a corresponding detection is also possible by a camera  29 . 
         [0040]    Thereby a defined orientation of the jigsaw  2  to the work piece  5  oriented at reference characteristics  28  is possible, may it for example be an edge  39  and/or a grain  32 , and corresponding with this orientation also the driving along a working line  24 , which is equivalent to a read in or programmed trajectory  41  and which is based on a starting point  40  on the side of the work piece, which almost corresponds on the side of the machine as initial point of the trajectory  41  with the rotational axis  22  of the saw blade  5 . Such a trajectory  41  is for example indicated by dotted lines in  FIG. 3 , the corresponding working line  24  on the side of the work piece on the other side by a solid line, despite of the fact that the working line  24  is not provided as a mark at the work piece  5 . The illustration in  FIG. 3  is based on a reference line that is provided by the edge  39 , to which the jigsaw  2  is positioned vertically with its longitudinal axis  25 . Also this orientation towards the edge  39  as reference line, or to another corresponding reference line, is usefully illustrated for the user for example in the display field  37  when positioning the saw blade  8  in the starting point  40 . 
         [0041]    If the jigsaw  2  is lead towards the work piece  5  by the user, usually only a rough orientation of the jigsaw  2  towards the desired working direction as well as towards the correspondingly desired or also provided, for example marked starting point  40 , is provided. As soon as the work piece  5  is almost reached by this means and it is located in the detection area of the sensory tools  27 , deviations to the orientation towards the starting point  40  are usefully illustrated in the display field  37  and corresponding direction hints are provided. The same applies preferably also for the orientation of the jigsaw  2  towards the reference line. It is particularly advantageous to signalize a correct allocation, if necessary to activate the jigsaw  2  not until a correct allocation. 
         [0042]    A targeted approaching of the starting point  40  with the saw blade  8  of the jigsaw  2  is thereby at least basically possible, and therefore also based on the starting point  40  a working that this oriented along the starting line  24  is ensured, especially because a small offset, which can be compensated by an angular positioning of the saw blade  8  in the starting point  40 , can subsequently be balanced by rotating the saw blade  8  and the initially present offset has practically no effect on the cross section, because it is notched in the starting point  40  and based on that an orientation of the saw blade  8  towards the working line  24  takes place. 
         [0043]    With the procedure according to the invention, which reliably enables the driving along a working line  24  guided by a user or semi-autonomous based on a corresponding starting point  40 , good work results can be achieved in a user guided as well as semi-autonomous operating. User guided at a not rotating saw blade  8 , or at most at a manually rotating saw blade  8 , for example by the guide knob  14  due to the guiding hints for example in the display field  37 , in semi-autonomous operation due to the guidance by the saw blade  8  at a supporting and advancing on the side of the user perhaps in the direction of the working line  24 , thus at an appropriate handling of the machine tool  1  by the user. 
         [0044]    In particular at a rotating saw blade  8 , and thus in a semi-autonomous operation, also relatively narrow radii can be sawed, whereby the danger increases that the user does not take this into account in his supporting of the jigsaw  2  or in the orientation of his advance force and/or advance speed that is oriented towards the jigsaw  2 . In order to prevent damages at the work piece  5  and/or at the tool in such cases, in particular the saw blade  8 , it proves to be useful if an adaptive adjustment of the working speed of the tool towards the advance speed takes place, and this in particular under consideration of the corresponding course of the working line  24 . The adjustment of the working speed is usefully undertaken by changing the number of strokes of the saw blade  8 .