Abstract:
A tool for treatment of rock, masonry or concrete by drilling, grinding or cutting off, the tool has a plurality of cutting segments each having a plurality of bonded cutting bodies formed as diamond crystals and subjected to an abrasive wear during an operation, a tool base body which carries the cutting segments, and at least one marking provided on at least one segment and forming a wear indicator, the at least one marking being arranged so that it changes during operation of the tool with wear of the cutting segments.

Description:
BACKGROUND OF THE INVENTION 
     The present invention generally relates to tools. More particularly, it relates to a tool which is used for treatment of rock, masonry or concrete. 
     A tool, in particular for treatment of rock, masonry or concrete is disclosed for example in the European patent document EP-B-514 822 and formed as a rock drill. The rock drill is provided with eight cutting segments which are distributed over the periphery and composed of a plurality of bonded cutting bodies, in particular diamond crystals. During the working operations they are subjected to material-removing wear. The cutting segments are mounted on a tool base body. In order to differentiate different types of cutting segments, marks are provided in the cutting segments. They distinguish from the binding medium of the corresponding cutting segment by color and during a corresponding application of the tool can not be lost. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a tool of the above mentioned general type, in which the use condition of the tool can be determined in a simple manner without comparison with other, non-used tools. 
     In keeping with these objects and with others which will become apparent herein after, one feature president invention resides, briefly stated, in a tool, in particular for treatment of rock, masonry or concrete, for example by drilling, grinding or cutting off, which has a plurality of cutting segments composed of a plurality of bonded cutting grains such as diamond crystals and subjected during the operation to a material-removing wear, and which also has a tool base body which carries the cutting segments, wherein in accordance with the present invention at least one cutting segment has at least one mark which serves as a wear indicator for the tool, in that the at least one marking is arranged so that its appearance or property or its relative length to cutting surface of the cutting segment change during the use of the tool as a result of the wear. 
     When the tool is designed in accordance with the present invention, it provides for the above mentioned highly advantageous results. 
     In accordance with another feature of the present invention, the marking can be formed as an indicator provided on the tool and formed and as a scale with associated value data. It can be arranged at least partially on the tool base body, and applied after the production of the cutting segments on the tool, for example by a laser treatment. On the other hand, the mark can be also applied on the cutting segment during the manufacture of the tool. 
     In accordance with another feature of the present invention, the marking can be formed as at least one intermediate member provided in at least one cutting segment and having a cross-section which is changeable in the abrasion direction of the cutting segment. The intermediate member can be different from the cutting segment by color. 
     Also, the marking can be formed by differently deep axial notches in the outer periphery of the cutting segments, by several axial throughgoing openings in the cutting segment, by lines, etc. 
     The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1-6 are views showing tools which are formed as cutting off disks and are provided with various markings for determination of a wear condition of the tool, in accordance with the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     A tool in accordance with the present invention, which is disclosed in this application as an example, can be formed as a cutting off disk  10  shown in FIG.  1 . The cutting off disk has a tool base body  11  which has a substantially disk-shaped construction. The tool base body  11  has a central mounting hole  12  for mounting of the cutting off disk  10  on the drive shaft of a not shown angular grinder. 
     The cutting off disk  10  is provided with a plurality of cutting segments  13  which are arranged on its outer periphery and uniformly distributed over it. The cutting segments  13  each have a plurality of cutting grains, in particular diamond crystals which are bound by means of a suitable binder. The binder for the inventive cutting off disk can be for example a metal alloy, such as bronze. It is mixed in a powder form with the cutting grains and thereafter is sintered. The cutting segments  13  are mounted each on a supporting piece  15  of the base body  11 . The neighboring supporting pieces  15  are separated from one another by a radially outwardly open slot  14 . For preventing a notch action, the slots  14  are provided at their inner ends with circular passages  23 . 
     The cutting segments  13  during the use of the cutting off disk  10  are subjected to abrasive wear. In other words, with the increased use of the cutting off disk  10  they become smaller. In order to determine the wear condition of the cutting segments  13 , in this embodiment the cutting segment  13 ′ is provided with three markings  16 . The markings  16  are formed as axial notches which are provided on the outer periphery of the cutting segments  13 ′ and have different depths. A first notch  16   a  has a radial depth which extends over substantially three quarters of the radial thickness of the cutting segment  13 ′. A second notch  16   b  extends over substantially the half of the radial thickness of the cutting segment  13 ′. A third notch  16   c  extends over substantially a quarter of the radial thickness of the cutting segment  13 ′. 
     During the use of the cutting segments  13 ,  13 ′ over their service life, they are subjected to abrasion or wear, by which the dimensions of the notches  16   a ,  16   b ,  16   c  and thereby the appearance of the markings  16  are changed. With the increased wear, the relative length of the markings  16  to a cutting surface  17  of the cutting segments  13 ,  13 ′ changes. With increased wear the notches  16   a ,  16   b ,  16   c  become smaller, until approximately at three quarters of the maximum thickness of the cutting segments  13 ,  13 ′, the notches  16   a ,  16   b ,  16   c  are completely removed. 
     The markings  16  with the notches  16   a ,  16   b ,  16   c  are applied preferably during the production of the cutting segments  13  in the cutting surface  17  of the cutting segment  13 ′. This can be performed for example by a laser treatment. In addition to the markings  16 , an indicator  24  formed as a scale can be provided on an end side of the tool base body  11  by means of laser engraving. The scale can have value data, such as for example one quarter, two quarters, three quarters, etc., which are associated with the corresponding notches  16   a ,  16   b ,  16   c.    
     FIG. 2 shows a second embodiment of the tool in accordance with the present invention. Same or similar parts of this embodiment are identified with the same reference numerals. 
     In FIG. 2 the cut off disk  10  also has a plurality of cutting segments  13  with a special segment  13 ′ provided with the markings  16 . The markings  16  here are formed as axial openings  18   a ,  18   b ,  18   c  which are located in the region X of the cutting segment  13 ′ shown on an enlarged scale in FIG. 2 a . The openings  18   a ,  18   b ,  18   c  have different radial distances from a central axis  26  of the cutting off disk  10 . The openings  18   a ,  18   b ,  18   c  open at the end side of the cutting segment  13 ′ and thereby are easy to observe. With increased wear of the cutting segment  13 ′, the relative position of the openings  18   a ,  18   b ,  18   c  to the cutting surface  17  changes. The openings  18   a ,  18   b ,  18   c  become closer to the cutting surface  17  when the surrounding material is removed during the operation. As can be seen from FIG. 2, in this embodiment also an indicator  24  with a scale is provided. 
     FIG. 3 shows the tool in which the markings  16  are formed by lines  19   a ,  19   b ,  19   c . The lines extend substantially parallel to a tangent to the outer periphery of the tool  10  and are laterally open on different cutting segments  13 ′ at different radial distances from the central axis  26 . The lines  19   a ,  19   b ,  19   c  extend partially on the tool base body  11 , on which also the scale  24  is provided. The wear condition is therefore determined by the position of the corresponding intersection point of the cutting surface  17  and the lines  19 . 
     FIG. 4 shows another embodiment of the tool in accordance with the present invention. Here the cutting segments  13 ′ which carries the marking  16  has an incline  20  in a peripheral direction. Its length forms a value for the wear condition of the tool  10 . The indicator  24  is formed by parallel, radially extending lines  19 . Corresponding value data are associated with the lines. 
     FIG. 5 shows a tool in accordance with still another embodiment of the present invention, in which the markings  16  are arranged in the center of the segment  13 ′ and formed by a single, wide notch  21  having lateral inclined surfaces  25 . The size of the notch  21  with the inclined surfaces  25  represents a value for the wear condition of the tool  10 . The indicator  24  is formed by a pair of lines  25  which have a different parallel distance and end in the region of the notch  21 . 
     Finally, the tool in accordance with the embodiment of FIG. 1 has the marking  16  which is arranged between two neighboring cutting segments  13 ′. The marking  16  has an intermediate member  22  which is conical in a radial direction and has a composition different from the material of the cutting segment  13 . With increased wear the cross-section of the marking  16  is reduced. The intermediate member  22  can be designed for example in color, so that it is different from the cutting segments  13 ′. The intermediate member  22  can be also integrated in one of the cutting segments  13 ′. 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
     While the invention has been illustrated and described as embodied in tool, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention. 
     What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims: