Abstract:
In order to obtain a simple, inexpensive and low-maintenance monitoring device for controlling the setting width of individual teeth of saw blades or belt-saw blades, in particular for controlling the setting result of a setting machine the present invention invisages that the monitoring device comprises at least one photo-detector whose light beam at least partly runs through one or both regions laterally next to the running-past saw blade or belt-saw blade, into said regions the set teeth project.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to a monitoring device for controlling the setting width of individual teeth of saw blades or belt-saw blades, in particular for controlling the setting result of a setting machine.  
           [0002]    From DE 195 17 482 A1 it is known to determine the deviation of an actual setting from a nominal setting by way of a contact-less monitoring, e.g. opto-electronically.  
           [0003]    Usually for the opto-electronic monitoring of the setting result there are applied line cameras in order with this to document the result and with the presence of a deviation of the actual setting width from the nominal setting width an automatic correction of the setting machine is carried out. These cameras have the disadvantage that they are expensive and sensitive to contamination and that an exact focussing onto the region to be monitored is necessary. By way of this there arises a considerable maintenance expense for the exact adjusting and monitoring of the focussing and for the regular cleaning of the camera. Otherwise one must reckon with unusable results.  
         BRIEF SUMMARY OF THE INVENTION  
         [0004]    It is the object of the invention to specify a monitoring device of the previously mentioned type, which with relatively low manufacturing costs ensures a reliable operation with as low as possible maintenance.  
           [0005]    The object is achieved by the invention in that the monitoring device comprises at least one photo-detector whose light beam at least partly runs through one or both regions laterally next to the running-past saw blade or belt-saw blade, into said regions the set teeth project. Photo-detectors are very much more inexpensive to obtain and adjust than a line camera. With the use of narrow parallel light beams between the light emitter and light receiver an exact focussing onto the region to be monitored may advantageously be done away with. Since a lens for imaging the region to be monitored onto a camera line is done away with with the device according to the invention this also may not get contaminated and the maintenance expense is correspondingly reduced.  
           [0006]    Although as a rule one photo-detector would be sufficient in order to monitor both sides of the saw blade, for example using a mirror, an embodiment form of the invention is preferred in which two photo-detectors are provided for monitoring both lateral regions of the saw blade or belt-saw blade.  
           [0007]    If the photo-detector comprises a laser, one obtains a sharply limited parallel light beam which is very well suited to the monitoring of the setting result.  
           [0008]    In a further formation of the invention it is envisaged that the photo-detector is designed as a laser scanner with which the laser serving as a light emitter on the one side and a light receiver on the other side are connected to one another by a U-shaped bow and thus are adjusted and fixed in their relative position to one another.  
           [0009]    Such a laser scanner may according to a further formation of the invention in each case be assembled on a laterally traversable and fixable carriage in order to be able to particularly simply and safely carry out the exact setting of the light beam onto the region to be monitored.  
           [0010]    If the light beam with respect to the plane of the saw blade or belt-saw blade has a small angle, with respect to the optical conditions in the region of the teeth projecting laterally to the right and the left of the saw blade there results no essential change with respect to the arrangement of the light beam parallel to the saw blade. The mentioned arrangement however has the advantage that in contrast to the parallel arrangement of the light beam the backing of the saw may not falsify the measuring result. If this backing on account of any type of disorder of the belt-saw blade advance is laterally deflected, with the arrangement according to the invention it may not get into the region of the light beam.  
           [0011]    In an advantageous formation of the invention it is envisaged that the cross section of the light beam effective for the monitoring is dimensioned and arranged in a manner such that it essentially encompasses half the belt-saw blade body and the maximum setting width. By way of the overlapping of the light beam with the belt-saw blade body apart from the setting result simultaneously the middle position of the set tooth to the belt-saw blade body may be monitored and where appropriate corrected.  
           [0012]    In order to ensure a centering which is required for a reliable determining of the setting width there is provided a centering device which centers the running-past belt-saw blade with respect to the photo-detectors.  
           [0013]    In one formation of the centering device this comprises two lateral jaws which are movably guided perpendicular to the saw blade plane and which are elastically pressable laterally onto the belt-saw blade, which is preferably effected pneumatically, wherein further there is provided a mechanical synchronization of a movement of the two jaws in opposite directions. In this manner the elastically mounted jaws may continuously laterally yield should the thicknesss of the belt-saw blade change or other lateral forces occur by way of disorder, for example by way of the waviness of the belt-saw blade. With this it is however always guaranteed that the jaws in each case are displaced by the same path distance one the one hand to the right and on the other hand to the left so that also a thicker belt-saw blade is always led symmetrically to a middle plane lying between the jaws.  
           [0014]    In a further formation of the synchronization it is envisaged that the jaws in each case are connected to a rack, and that the toothings of the rack are in engagement with opposite sides of a pinion.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    One embodiment example of the invention is hereinafter described in more detail by way of the drawings. The figures with this individually show  
         [0016]    [0016]FIG. 1: a part of a saw blade in a lateral view;  
         [0017]    [0017]FIG. 2: an enlarged plan view from direction A of FIG. 1 of the same saw blade;  
         [0018]    [0018]FIG. 3: a schematic represention of a monitoring device according to the invention;  
         [0019]    [0019]FIG. 4: a schematic representation of a centering device.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    In FIG. 1 one recognises a belt-saw blade  1  which normally is provided for use in belt-saw blade saws. The belt-saw blade  1  has teeth  2  which are arranged on a belt-saw blade body  5  and are designed as one piece with this. The setting of bi-metal belt-saw blades is of course likewise possible. Along a line  3 , the teeth  2 , as also shown in FIG. 2, are lateraly bent out of the plane of the belt-saw blade body  5  to the front and to the rear, so that there arise two groups of teeth, specifically a tooth group  2   a  which is bent to one side of the belt-saw blade  1 , and a tooth group  2   b  which is bent to the other side of the belt-saw blade  1 . Each tooth group  2   a ,  2   b  defines a setting width indicated by way of the dashes  4   a ,  4   b.    
         [0021]    The setting is normally carried out in an automatic setting machine, wherein disorders may occur with the result that the actual setting width deviates from the nominal setting width. Since the setting width  4  on the other hand is decisive for the perfect functioning of the belt-saw blade, the setting result must be monitored and given deviations from the nominal value where possible automatically corrected. At least in this case an alarm must be triggered.  
         [0022]    For the monitoring of the setting result there is provided a monitoring device  6  schematically represented in FIG. 3. The monitoring device  6  comprises two photo-detectors  7 ,  8  which in each case have a light emitter S and a light receiver E arranged opposite the light emitter S. The light emitter S consists of two lasers from which laser beams  9 ,  10  proceed which meet in the respectively allocated light receiver E. In the middle of FIG. 3 one recognises the belt-saw blade  1  in section in one view according to a direction indicated with B in the FIGS. 1 and 2. The belt-saw blade body  5  is centered with respect to a middle plane by way of a centering device described further below, wherein the teeth  2   a ,  2   b  project laterally to the left and right respectively.  
         [0023]    The two laser beams  9 ,  10  are arranged in a manner such that they irradiate the two regions on the right and left side of the belt-saw blade  1  into which the laterally set teeth  2   a  and  2   b  respectively project. With this, laser beam  9  is provided for monitoring the teeth projecting out to the right and laser beam  10  for monitoring the teeth  2   a  projecting out to the left. Preferably the light photo-detectors with a light emitter S and with a light receiver E are designed as laser scanners, i.e. are rigidly connected by way of a U-shaped bow. The laser scanners are preferably in turn mounted on a carriage which is not shown, so that each photo-detector is displaceable as a unit in the arrow direction  12  and after adjusting the respective laser beam  9 ,  10  are fixable onto the region to be monitored.  
         [0024]    The belt-saw blade  1  for checking the setting result is transported in the advance direction  13  (see FIG. 1) through the monitoring device. In order to avoid disorders of the measuring result by way of lateral movements of the belt-saw blade body  5  into the region of a laser beam  9 ,  10  the laser beams are not arranged parallel to the belt-saw blade body  5  or to the middle plane  11 , but at a small angle  14  to the middle plane  11 . Furthermore the cross sections of the laser beams  9 ,  10  are dimensioned such that apart from overlapping the maximum setting width  4   a ,  4   b  they also approximaltely overlap half the thickness of the belt-saw blade body  5 . By way of this the relative position of the belt-saw blade body  5  to the middle plane may be optically recorded and evaluated, since at the moment when the respective laser beam  9  beams through the gap between two teeth  2   a  and  2   b  it is still only partly shadowed by the section of the belt-saw blade body which projects into the region of the laser beam  9  and  10 .  
         [0025]    The signals being emitted from the light receivers are via measuring conduits  15  led to evaluation electronics which preferably consist of a programmable microprocessor. With deviations of the setting result from the predetermined nominal setting width via a signal conduit  17  either an alarm may be triggered or a correcting intervention in the setting machine may be automatically effected. The same applies for a deviation of the belt-saw blade body  5  from the middle position defined by the middle plane  11 .  
         [0026]    In order to hold the belt-saw blade body  5  as centered as possible there is provided a centering device shown in FIG. 4. This consists of two centering jaws  18 ,  19  which in each case in associated parallel guides  20 ,  21  are movably guided perpendicularly to the saw blade plane or to the middle plane  11  in the arrow direction  12  and by way of two pneumatic pressing devices  22 ,  23  are elastically pressed onto the belt-saw blade body  5  of the belt-saw blade  1  in order to guide the belt-saw blade  1 . In order to ensure that the guiding of the belt-saw blade  1  is always effected symmetrically to the middle plane  11  the movement of the two centering jaws  18 ,  19  in the arrow direction  12  is sychronized to one another in opposite directions. For the synchronization the two centering jaws  18 ,  19  are in each case connected to a rack  24 ,  25 , wherein the respective toothings of the racks bear on opposite sides of a pinion  26  and are in engagement with the toothing of the pinion. With a movement of a centering jaw  18  as a result the other centering jaw  19  is forced into an opposite movement so that the guiding of the belt-saw blade  1  is effected always symmetrically to the middle plane also with changes of the belt-saw blade thickness.  
       LIST OF REFERENCE NUMERALS  
       [0027]    [0027] 1  belt-saw blade  
         [0028]    [0028] 2  teeth  
         [0029]    [0029] 2   a  tooth group  
         [0030]    [0030] 2   b  tooth group  
         [0031]    [0031] 3  line  
         [0032]    [0032] 4   a  setting width  
         [0033]    [0033] 4   b  setting width  
         [0034]    [0034] 5  belt width  
         [0035]    [0035] 6  monitoring device  
         [0036]    [0036] 7  photo-detector  
         [0037]    [0037] 8  photo-detector  
         [0038]    [0038] 9  laser beam  
         [0039]    [0039] 10  laser beam  
         [0040]    [0040] 11  middle plane  
         [0041]    [0041] 12  arrow direction  
         [0042]    [0042] 13  advance direction  
         [0043]    [0043] 14  angle  
         [0044]    [0044] 15  measuring conduit  
         [0045]    [0045] 16  evaluation electronics  
         [0046]    [0046] 17  signal conduit  
         [0047]    [0047] 18  centering jaw  
         [0048]    [0048] 19  centering jaw  
         [0049]    [0049] 20  parallel guide  
         [0050]    [0050] 21  parallel guide  
         [0051]    [0051] 22  pressing device  
         [0052]    [0052] 23  pressing device  
         [0053]    [0053] 24  rack  
         [0054]    [0054] 25  rack  
         [0055]    [0055] 26  pinion  
         [0056]    S light emitter/laser  
         [0057]    E light receiver