Abstract:
A metal cutting tool has a supporting tool, which has a recess for accommodating a cutting plate. The cutting plate is provided with a damping trough, which is held in the supporting tool by a clamping claw. The clamping claw is fixed against the supporting tool by a clamping screw. A pressure piece is placed on the clamping claw and its underside facing the cutting plate is provided with a cam, which is in contact with the clamping trough and the clamping claw pulls the pressure piece toward the clamping screw.

Description:
[0001]    This application is a continuation of U.S. patent application Ser. No. 13/427,325 filed Mar. 22, 2012, pending, hereby incorporated by reference in its entirety, which is a continuation of U.S. Ser. No. 11/528,788 filed Sep. 28, 2006, now U.S. Pat. No. 8,388,273 B2, incorporated herein by reference in its entirety, which is a continuation of U.S. Ser. No. 10/483,886 filed Jun. 10, 2004, abandoned, which is a §371 of PCT/DE02/02665 filed Jul. 19, 2002, and claims priority from German 101 36 635.3 filed Jul. 26, 2001 and 102 08 266.9 filed Feb. 26, 2002. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to a metal-cutting tool and an associated cutting plate. 
         [0003]    The prior art for a cutting insert, here an indexable cutting plate made of ceramic material, is constituted by cutting plates that have a smooth surface or that have a great variety of clamping troughs and are inserted so as to be clamped in a supporting tool for the purpose of machining metallic materials. The disadvantage of this technology in the case of smooth cutting plate surfaces is the lack of a form-locking connection with the supporting tool with respect to the clamping force. In the case of cutting plates that have a clamping trough admittedly there is in addition a form-locking connection, but as a result of the clamping in the clamping trough the cutting plate is loaded by the clamping elements in terms of force to a very great extent over a comparatively small area, something which can lead to stresses in the cutting plate or even breakages. Furthermore, in the case of the clamping systems that exist today not all the possible positive factors are combined in one system. 
         [0004]    A metal-cutting tool, substantially consisting of a supporting tool which has a recess to accommodate a cutting plate that is provided with a clamping trough held in the supporting tool by a clamping claw, the clamping claw being fixed on the supporting tool by way of a clamping screw, is known from EP 0 753 366 B1. Arranged on the clamping claw there is a pressure piece which, on the underside facing the cutting plate, is provided with a cam which is in tight contact with the clamping trough. Furthermore, the clamping claw pulls the pressure piece in the direction of the clamping screw. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0005]    The underlying object of the invention is to combine, by means of simple components, as many positive factors in one system as possible and to achieve an optimum clamping situation as a result of the cooperation thereof. In this connection, the manufacturing tolerances of the various components are to be compensated for, an additional form-locking connection with controlled clamping-force limitation is to result, and a configuration of the component parts that counteracts the machining forces is to be used as a basis for avoiding a loss of clamping force during use. 
         [0006]    In accordance with the invention this object is achieved by according to the present invention. 
         [0007]    In accordance with the invention, the clamping trough is formed in a circular shape and in the center has a spherical or circular elevation. The cam on the pressure piece consists of a circular ring that is adapted thereto and tightly engages into the clamping trough whilst surrounding the elevation. As a result an optimum fit of the cutting plate in the supporting tool is guaranteed. 
         [0008]    In an advantageous development, the clamping claw has on its underside located above the pressure piece a spherical elevation which engages into a spherical depression on the pressure piece. 
         [0009]    In this connection, the radius of the spherical elevation on the clamping claw is advantageously greater than the radius of the spherical depression in the pressure piece, as a result of which a transmission of force can be effected by way of the outer edges. 
         [0010]    The pressure piece is preferably secured to the clamping claw with clearance by a way of a screw. 
         [0011]    In order to protect the clamping claw from impinging filings, expediently the pressure piece has a raised part on the front side. 
         [0012]    The pressure piece preferably consists of a wear-resistant material, such as hard metal, HSS or ceramic material. 
         [0013]    In a preferred development, an open region centrically or concentrically surrounds the ring on the pressure piece, and this open region is centrically or concentrically surrounded by a bearing surface that rises towards the center of the ring at an angle. 
         [0014]    The clamping claw is advantageously guided on the supporting tool by way of an incline with a form of clamping-force limitation. 
         [0015]    In an alternative embodiment, the clamping claw is guided on the supporting tool by way of two inclines, with the two inclines extending in parallel and being separated from each other by way of a slit. 
         [0016]    The two inclines advantageously extend at an angle of 10° to 45° in relation to the longitudinal axis of the clamping claw. 
         [0017]    Advantageously, the two inclines have a cylindrical surface, and the supporting tool has cylindrical lateral surfaces adapted thereto. 
         [0018]    A cutting plate in accordance with the invention is provided with a clamping trough, with the clamping trough being formed in a circular shape and having a spherical or circular elevation in the center and being capable of being installed in the cutting tool that has been described. 
         [0019]    The formation as an indexable cutting plate is advantageous. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  shows a view of a cutting plate in accordance with the invention; 
           [0021]      FIG. 2  shows a view of the cutting tool with the cutting plate inserted; 
           [0022]      FIG. 3  shows the cutting tool in accordance with  FIG. 2  in an exploded view; 
           [0023]      FIG. 4  shows the cutting tool in accordance with  FIG. 2  in section; 
           [0024]      FIG. 5  shows an enlarged view of the cooperation between the clamping claw, the pressure piece and the cutting plate; 
           [0025]      FIG. 6  shows a section through a clamping trough; 
           [0026]      FIG. 7  shows a view of the upper side of a pressure piece; 
           [0027]      FIG. 8  shows a view of the underside of a pressure piece; 
           [0028]      FIG. 9  shows a view of a clamping claw; 
           [0029]      FIG. 10  shows an enlarged section of the clamping claw, the pressure piece and the cutting plate; 
           [0030]      FIG. 11  shows the underside of a further variant of the clamping claw; 
           [0031]      FIG. 12  shows a slit in the clamping jaw; 
           [0032]      FIG. 13  shows the cylindrical surface of the two inclines; and 
           [0033]      FIG. 14  shows the cooperation of the clamping claw and the supporting tool cross section. 
       
    
    
     DETAILED DESCRIPTION  
       [0034]      FIG. 1  shows a cutting insert or a cutting plate  10  as an indexable cutting plate for the metal-removing processing of metallic work pieces. The cutting plate  10  has in the centre a circular clamping trough  11 , with there being positioned in turn in the centre of the latter a spherical or circular elevation  12 . This clamping trough  11  and elevation  12  are to be used to fix the cutting plate in an appropriate receiver, here called a plate seat, on a suitable supporting tool. 
         [0035]      FIG. 2  shows the spatial representation of the cutting plate  10  that has been described in the clamped state on a supporting tool  13 . Special attention is to be given in this connection to the pressure piece  14  (see also  FIG. 3 ) which on the underside has the counter-form of the clamping trough in the cutting plate previously described. The clamping force that develops as a result of tightening the clamping screw  17  is transferred by way of the clamping claw  16  to the cutting plate  10 . As a special feature, the clamping claw has, on the underside located above the cutting plate, a spherical elevation  18  which projects into a spherical depression  19  in the pressure piece  14  and is secured with clearance by means of the screw  15 . 
         [0036]    A cross section through the plate seat is shown in  FIG. 4  in which the cooperation of the clamping elements shall be described. When tightening the clamping screw  17 , the clamping claw  16  moves downwards and at the same time slides backwards with the incline  20  on a similar incline in the supporting tool. Since the clamping claw by way of the spherical elevation  18  on the side lying opposite the incline and as a result of the clamping force that develops is connected to the pressure piece  14  in a form-locking manner by means of the spherical depression  19 , and since the elevation  21  of the pressure piece in turn engages in a form-locking manner into the trough of the cutting plate, the movement that is directed sideways into the plate-seat corner is transferred by means of the individual clamping elements to the cutting plate. See also in this connection  FIG. 10 . When the clamping-force limitation  22  is reached, the lever movement of the clamping claw is increased. The pressure piece  14  exerts an even greater pressure on the cutting plate and now also additionally presses with its bearing surface  23  on the surface of the cutting plate. The outstanding feature of this cooperation is that with the combination of all the elements the cutting plate is no longer able to move out from its plate seat as a result of the forms and inclines that are provided. 
         [0037]      FIG. 5  again shows an enlarged view of the cooperation of the clamping claw, the pressure piece and the cutting plate. 
         [0038]      FIG. 6  shows a section through the circular trough  11  of the cutting plate. In the centre of the latter can be seen the circular or spherical elevation  12 . A special feature in this connection is that the elevation  12  has the shape of a sphere and lies above the trough base and below the cutting plate surface. The trough contour is circular in cross section and runs as it were about the perpendicular axis of the sphere, this being reminiscent of the baking tin of the American donut. 
         [0039]    The upper side of the pressure piece  14 , which has as a special feature the described spherical indentation  19  or spherical hollow or depression, is shown in  FIG. 7 . 
         [0040]    The underside of the pressure piece  14  which has, as a special feature, an elevation  21 , a donut shape, which is the counter-form of the clamping trough on the cutting plate, is shown in  FIG. 8 . Additional features are the bearing surface  23 , which rises at an angle towards the centre of the donut, and the open region  25  which is to protect the trough edge of the cutting plate from surface contact and thus damage and insufficient seating. See also in this connection  FIG. 10 . 
         [0041]    A further special feature of the pressure piece is its constitution, being made from a wear-resistant material, such as hard metal, HSS or ceramic material, and the raised part  24  of the outer contour to protect the clamping claw from the filings which are formed during machining (see  FIG. 7 ). The sphere/spherical-indentation connection is also used for tolerance and position-compensation between the clamping element and the cutting plate. 
         [0042]      FIG. 9  shows the underside of the clamping claw with the spherical elevation  18  which has been described. A special feature of this sphere is, moreover, the fact that the diameter of the sphere is somewhat greater than the diameter of the spherical indentation in the pressure piece  14  in order to enable there to be transmission of force by way of the sphere/spherical-indentation outer edges  26 , see  FIG. 10 , and not by way of punctiform loading at the spherical-indentation base and the tip of the sphere. A further feature is the incline  20  on the clamping claw (see  FIG. 4  and  FIG. 9 ) which guides by way of an incline in the supporting tool. These inclines have the effect that when tightening the clamping screw a lateral movement of the clamping elements is effected that is to pull the cutting plate into the corner of the plate seat. This clamping claw is intended for supporting tools that have comparatively small dimensions. 
         [0043]      FIG. 11  shows the underside of a further variant of the clamping claw  16  with the spherical elevation  18  that has been described. This clamping claw  16  is intended for supporting tools whose dimensions permit the installation of this element which is comparatively large on account of its manner of construction. A special feature of this clamping claw is the incline  26  which is shaped differently in the rear region in comparison with that in  FIG. 9 . It extends, as can be seen in  FIG. 12 , separated by a slit  27 , at an angle of 10° to 45°. The inventive feature of these two inclines  26  is provided by their cylindrical surfaces  28 . These have the effect that when tightening the clamping screw in addition to the lateral movement of the clamping claw self-centering in a recess  29  specifically produced therefor is effected on the corresponding supporting tool  13 . See in this connection  FIG. 13 . 
         [0044]    The special feature of the recess  29  on the supporting tool  13  in  FIG. 13  is in turn the cylindrical surface of the two inclines  30  which extend in parallel and the radius of which is designed so as to be somewhat greater than the cylindrical surfaces  28  of the clamping claw. This consequently renders possible an approximate line contact between the inclines and a self-centering sliding movement along the contacting lateral cylinder surfaces  28  and  30 .  FIG. 14  shows this cooperation of the clamping claw and the supporting tool in cross section.