Abstract:
In a roughness scanner comprising a scanning arm with a scanning needle mounted at one end thereof, a skid carrier having an end supporting a skid with the scanning arm extending along the skid carrier in spaced relationship therefrom, the skid has at one side a guide plate including an opening through which the scanning needle extends and a space formed above the guide plate which space is open at least at one side thereof down to the guide plate, so that any liquid collected by the needle and moving upward into the space above the guide plate can flow again out of that space.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This is a continuation-in-part application of pending international application PCT/EP2006/007053 filed Jul. 18, 2006 and claiming the priority of German Application No. 10 2005 035 786.5 filed Jul. 27, 2005. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The invention resides in a roughness scanner particularly for industrial applications, but also for laboratory use. 
         [0003]    Roughness scanners are used to determine the roughness of a surface. To this end, the roughness scanner includes a skid of a size of a few millimeters which is in contact with the workpiece. A very fine scanner needle extends through an opening in the skid and into contact with the workpiece surface. The vibrations of the scanner needle caused by the roughness of the surface during the skid over the workpiece are picked up just like in a record player and converted into electrical signals and are evaluated for determining a characteristic roughness value. 
         [0004]    The scanner needle and the skid are very small components which are also very sensitive. The opening through which the scanner needle extends is, for example, only one millimeter wide or even smaller. Although it is not in compliance with the measuring specifications, the roughness scanners may at times come into contact with oily workpiece surfaces. Such problems occur mainly during use in connection with manufacturing equipment. The oil present on the workpiece surface then accumulates around the scanner needle in the skid opening whereby it is slowly transported by the vibrations of the needle into interior of the roughness scanner. However, because of its viscosity the oil influences the measurements undesirably, so that the measuring results of such a roughness scanner are no longer reliable. It must therefore be flushed out which, because of the small dimensions of the roughness scanner requires special skills. Furthermore, it is difficult to remove solvent or flushing medium from the roughness scanner. They adhere, for example, to the surfaces areas between the skid and the scanner needle because of capillary effects. A visual examination whether the gap around the scanner needle is free from solvents or flushing liquids, washing liquids, oils or similar media, is impossible without magnifier and is even with a magnifier not reliably possible. 
         [0005]    It is therefore the object of the present invention to provide a roughness scanner, which is usable reliably also in connection with manufacturing procedures. 
       SUMMARY OF THE INVENTION 
       [0006]    In a roughness scanner comprising a scanning arm with a scanning needle mounted at one end thereof, a skid carrier having an end supporting a skid with the scanning arm extending along the skid carrier in spaced relationship therefrom, the skid has at one side a guide plate including an opening through which the scanning needle extends and a space formed above the guide plate which space is open at least at one side thereof down to the guide plate, so that any liquid collected by the needle and moving upward into the space above the guide plate can flow again out of that space. 
         [0007]    Since the opening receiving the scanner needle is open toward the front and/or the rear the cleaning fluid can be admitted to the scanner needle without difficulty and can also be again removed. It is also easily possible to clean the gap formed by the skid around the scanner needle with compressed air. 
         [0008]    The capillary effect otherwise present between the scanner needle and the skid opening causes a pumping effect by which otherwise oil is directed into the roughness scanner. This pumping effect is eliminated by the open configuration of the skid. Oil which has entered between the skid and the scanner needle can be discharged again toward the front and the rear. In any case, it is not conducted further into the roughness scanner. 
         [0009]    The scanner needle preferably is a diamond tip or a steel needle which is provided with a diamond tip. It extends through the opening provided in the skid without contacting the wall thereof. Preferably the scanner tip narrows down in this area, that is, it has, for example, a cone-like shape. 
         [0010]    The plate, which is formed at the skid and though which the scanner needle extends, is preferably slightly arched at it end facing the workpiece. The arch can have a curvature in the direction of movement of the scanner or in a direction transverse to the movement of the scanner. Also, the radii of the curvature may be different. A curvature transverse to the direction of movement makes it possible to hold the roughness scanner at slightly different angles with respect to the workpiece surface. It does not need to be oriented exactly parallel to the workpiece surface. The curvature in the direction of movement is advantageous if concave surface areas such as bare walls are scanned. 
         [0011]    The plate is connected to a clamp by at least one, but preferably two, support arms which project from the two long edges of the plate. An upper arched section of each arm forces the clamp for attaching the skid carrier. The space present between the two arms is, with respect to the direction of movement, preferably open toward the front as well as toward the rear. The respective opening extends preferably directly to the plate. Fluids which have entered the space between the arms via the opening provided in the plate can therefore freely flow out again. This reduces the soiling sensitivity of the roughness scanner and facilitates the cleaning thereof. 
         [0012]    Further features and advantageous embodiments of the invention will be described below on the basis of the accompanying drawings showing an embodiment of the roughness scanner according to the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  shows schematically the roughness scanner in a longitudinal cross-sectional view; 
           [0014]      FIG. 2  is an exploded perspective view of the roughness scanner according to  FIG. 1 ; 
           [0015]      FIG. 3  shows the skid of the roughness scanner according to  FIGS. 1 and 2  in a bottom view of the skid; 
           [0016]      FIG. 4  shows the skid of  FIG. 3  in a longitudinal cross-sectional view; 
           [0017]      FIG. 5  is a front view of the skid shown in  FIGS. 3 and 4 ; 
           [0018]      FIG. 6  is a perspective view of the skid shown in  FIGS. 3 to 5 , and; 
           [0019]      FIG. 7  shows a modified embodiment of the skid for a roughness scanner according to  FIG. 1  in a perspective view. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0020]      FIG. 1  shows a roughness scanner  1  having a base body  2  provided with a skid carrier  3  in the form of a tube which projects from the base body  2 . In place of a tubular skid carrier  3 , a skid carrier in the form of a U-profile may be used. Furthermore, it may be in the form of an oval tube, a circular tube, a rectangular tube or of similar shape. Through the skid carrier  3 , a lever arm  5  extends which is part of a scanning arm  4  and which carries at its free end a scanning needle  6 . The scanning needle  6  is held in a socket  7  which supports it at the end of the lever arm  5 . 
         [0021]    The scanning arm  4  is movably supported by the base body  2  via spring joints  8 ,  9  ( FIG. 2 ) and includes a second lever arm  10  which cooperates with a sensor  11  for picking up movements and position changes of the scanning arm  4 . Signals of the sensor  11  can be taken up from the outside via plug-in contact pins  12 ,  13 . 
         [0022]    The roughness scanner  1  preferably has a cylindrical outer shape. It is accommodated in a cylindrical housing  14  of an advancing apparatus which is not shown and is movable in a direction as indicated in  FIG. 1  by an arrow  15  for the scanning of a workpiece surface. To this end, the scanning needle  6  is provided with a scanning tip  17  which may be, for example, in the form of a diamond tip. 
         [0023]    The skid carrier  3  is provided at its end  18  remote from the base body  2  with a skid  19  by way of which the roughness scanner  1  is disposed on the workpiece surface  16 . The skid  19  supports the roughness scanner  1  on the workpiece surface  16  and forms the measurement reference for the deflection of the scanning tip  17 . At it bottom side, it includes a section in the form of a plate  20  which is polished at the bottom and, as shown in  FIGS. 4 ,  5  and  6 , is slightly curved.  FIG. 5  shows the curvature in a plane which extends in this case normal to the advancing direction. In this plane the curvature is clearly greater than the curvature shown in  FIG. 4  in a plane extending in the advancing direction. The underside of the plate  20  is polished, so that it can slide easily and smoothly across the workpiece surface. 
         [0024]    The plate  20  includes an opening  21  whose diameter, as shown in  FIG. 4 , is substantially greater than the thickness D of the plate  20 . The opening  21  is preferably arranged outside the center of the plate  20 . It is arranged closer to, with respect to the direction of movement  15 , rear edge  22  than to the front edge  23  of the plate  20 . 
         [0025]    Two essentially parallel legs  24 ,  25  ( FIG. 5  or  6 ) extend upwardly from the plate  20  so as to form between them a relatively wide space  26 . Above, the plate  20 , in the direction of movement  15 , front edge  23  and also above the rear edge  22  the plate  20  is not provided with upwardly extending legs, that is, the space  26  between the legs  24 ,  25  is provided toward the front and the rear with openings  27 ,  28 . 
         [0026]    The legs  24 ,  25  from at their upper ends clamping members  29 ,  30  in the form of sleeve members of semi-circular cross-section by which the skid  19  is engaged with the skid carrier  3 . 
         [0027]    For additional mounting of the skid  19  to the skid carrier  3 , a clamping piece  31  may be inserted into the end opening between the clamping members  29 ,  30  as approved from  FIG. 2 , which closes the skid carrier of the end like a plug. 
         [0028]    The roughness scanner  1  as described above operates as follows: 
         [0029]    During operation, the roughness scanner  1  is pulled in the advancing direction  15  over the workpiece surface  16 . The skid  19  slides herein with the lower arched and polished surface of the plate  20  over the workpiece surface  16 . At the same time, the scanning lip  17  scans the workpiece surface whereby the scanning needle  6  is subjected to microscopic movements normal to the workpiece surface  6 . The small pivot movements of the scanning arm  4  are detected by the sensor  11  and converted to electric signals which can be picked up. Any liquids present on the workpiece surface such as oil or oil residues may collect on the needle whereby the annular gap formed between the needle tip  17  and the wall of the opening  21  may be filled with the respective liquid. With additional accumulation, such liquids finally overflow over the top of the opening  21  and spread out on the top side of the plate  20 . However, there is no further accumulation. The liquids then can freely flow out via the rear and front edges  22 ,  23 . In any case, liquids will not move up along the scanning needle  6  and enter the skid carrier  3 . 
         [0030]    If it should become necessary to clean the roughness scanner  1 , it can easily be brushed with a cleaning liquid or a cleaning liquid may be sprayed onto it or it may be immersed into a cleaning liquid. It is also possible to spray cleaning liquids through the openings  27 ,  28  onto the scanning needle  6  and flush them out again or blow them out again by compressed air. Also, liquids collected on the scanning needle  6  during scanning such as oils may be directly blown out by compressed air. 
         [0031]      FIG. 7  shows a modified embodiment of a skid  19 ′. Based on the same reference numerals, the earlier description applies also to this embodiment. However, other then described earlier, the skid  19 ′ includes a space  26  which is not only open toward the opposite front and rear ends, but toward three sides. The plate  20  is only supported by the leg  25 ; the leg  24  is omitted. The clamping member  30  is enlarged, so that it alone is sufficient for supporting the skid  19 ′. It may, for example, extend over more than 180° around the skid carrier  3 . In this embodiment, the space  26  around the needle  6  is particularly well accessible. The opening  21  may be a bore as shown or, alternatively, it may be a passage in another form, for example, in the form of a slit. Such a slit may extend longitudinally or transverse to the advancing direction  15 . The same applies to the skid  19 . 
         [0032]    The roughness scanner  1  according to the invention includes a skid  19  which at least includes a relatively large opening  27  and/or  28  arranged above a plate  20  forming the actual skid structure and extending directly from the plate  20 . The scanning needle  6  extends at a relatively large distance from the walls  24 ,  25  defining the space between the legs  26  so that no capillary effects are present. Only between the wall of the opening  21  in the plate  20  a narrow annular gap is formed around the needle  6 . Liquids reaching this annular gap however are again conducted out as soon as they reach the space  26  between the legs  24 ,  25 . The liquids will not enter the interior of the roughness scanner  1 .