Abstract:
A groove cutting tool has a groove insert and a tool holder. The groove insert can be replaced by using a lever tool. The lever tool penetrates into a slot by way of an ejector portion and is able to assume several positions in the slot either in order to contact the groove insert and to push it out of its receiving means or in order to push away a clamping jaw and to open the receiving means for the groove insert.

Description:
CLAIM TO PRIORITY 
     This application is a National entry application of German Application No. 102012017424.1, filed on Sep. 4, 2012, the entire contents of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a tool holder for a groove cutting tool, to a groove insert and to the groove cutting tool itself. 
     BACKGROUND OF THE INVENTION 
     Groove inserts are built into rotary cutters or also milling cutters as a replaceable unit in order to be replaced when worn. Groove inserts are extremely small in size such that their secure fastening in the tool holder has to be ensured, also in the case of a lateral feed. 
     The groove inserts have lateral faces which are exposed in the tool, i.e. the groove inserts are received in a positively locking manner in the receiving means between their top surface and their bottom surface, possibly also their rear surface and are held by means of a clamping force. The opening of the receiving means for replacing the cutting insert is effected by means of a separate lever tool which is to be placed in position laterally and has a bearing continuation which penetrates into an opening in the tool holder and an ejector continuation which penetrates into a rear slot which proceeds from the receiving means. By pivoting the lever tool, the ejector continuation slips along a path and impacts against the bottom surface of the clamping jaw in order to raise said clamping jaw and to spread open the receiving means. As an alternative to this, the ejector continuation can be pressed against the rear surface of the groove insert in order to push said groove insert in the clamped state out of the receiving means. 
     As an alternative to this, there are solutions where the ejector continuation is able to penetrate into an opening of the clamping jaw and the clamping jaw is able to be moved directly upward. 
     DE 197 39 855 A1 shows a groove cutting tool having a tool holder where there is a slot on the rear surface proceeding from the receiving means. Said slot has a portion which is greater in cross section and into which the ejector continuation penetrates when inserted, and a connecting portion which tapers toward the receiving means and into which the ejector continuation is pressed when the tool holder is opened. When pivoting the lever tool in the direction of the groove insert, the clamping jaw is pressed upward and the groove insert is able to be pulled out. 
     SUMMARY OF THE INVENTION 
     It is the object of the invention to create a tool holder which simplifies the replacing of the groove insert. Furthermore, a groove insert which is optimized to the tool holder according to the invention is to be provided as well as a groove cutting tool which is distinguished by easier replacement of the cutting insert. 
     The tool holder according to the invention of a groove cutting tool has a receiving means for a groove insert, where the receiving means is defined on one side by a clamping jaw and on the other side by a base of the tool holder, and where the receiving means at the back of the groove insert merges into a slot which separates the clamping jaw from the base. The slot forms a connecting link for an ejector continuation of a lever tool which can be inserted laterally into the slot, and has several portions. Provided are a central insertion portion, an ejector portion which is adjacent to the insertion portion and leads to the receiving means as well as an expanding portion which leads from the insertion portion in the direction of the slot bottom for opening the receiving means. 
     In the case of the tool holder according to the invention there are a total of at least three positions for the lever tool. Along with the insertion portion which enables the insertion of the lever tool, it is possible to push out the groove insert directly in a direction proceeding from the insertion portion by the ejector portion pushing directly against the groove insert in order to release it from the support. The expanding portion proceeds from the insertion portion in the opposite direction, the slot tapering in this case. When the ejector continuation is moved out of the insertion portion into the expanding portion or when it is moved along the expanding portion, the ejector continuation presses against the bottom surface of the clamping jaw in order to pivot up said clamping jaw. The tool holder according to the invention consequently allows for either the groove insert to be pushed out directly or, as an alternative to this, the clamping jaw to be raised. 
     Between the insertion portion and the ejector portion and/or the insertion portion and the expanding portion the slot preferably has a stop nose which projects into the slot. Said stop nose separates the three portions from one another such that the ejector continuation of the lever tool initially has to overcome a resistance by slipping along the stop nose and having to push said stop nose away before it is able to pass into an adjacent portion of the slot. Consequently, the positions of the ejector continuation are clearly defined and no unwanted movement of the ejector continuation is able to occur. This has been possible in the past when there was a kind of springing-back of the clamping jaw when the lever tool was inserted. 
     The stop nose is preferably realized between the ejector portion and the insertion portion on the base-side edge of the slot and/or between the insertion portion and the expanding portion on the tool-holder-side edge of the slot. 
     According to one embodiment, between the insertion portion and the expanding portion the stop nose can at the same time form a tapering which is responsible for opening the tool holder when the ejector continuation is pressed into the expanding portion. 
     As an alternative to this or in addition to it, the expanding portion can, however, also have a reducing width proceeding from the insertion portion to the slot bottom. 
     The tool holder should have at least one pivot bearing opening for the lateral insertion of a pivot bearing continuation on the lever tool. Said pivot bearing continuation can preferably be provided on the base. 
     One option is also to realize the pivot bearing opening as an elongated hole such that, on the one hand, the pivot bearing opening acts as a pivot bearing and, on the other hand, as a longitudinal guide. 
     When viewed from the side, the slot can extend in a V-shaped manner, the insertion portion in particular lying in the deepest region of the “V” in this case. 
     The slot can start from a bottom edge of the receiving means, in particular from the transition of the bottom edge to a rear surface of the receiving means. It has been shown that a slot positioned in such a manner simplifies the realization of the different positions of the lever tool and reinforces clamping force through feed force as the top clamping jaw and the rear system are connected. 
     The receiving means can be defined at the edge by a profiled holding structure for forming positive locking with the groove insert; this means that the edge of the receiving means is profiled in portions, preferably completely over the entire length. The holding structure is realized, for example, as a V-groove or a trapezoidal groove, in particular as a prism groove. The form of the corresponding edge of the groove insert is complementary to this at least in portions. 
     The importance of the rear surface of the receiving means, i.e. the rear edge, is not to be underestimated for the supporting of the groove insert. Said edge, according to the preferred embodiment, also has a holding structure with a groove, in particular a prism groove. Said groove merges into the slot. 
     The ejector portion has a slot width and extends in relation to the pivot bearing opening such that the ejector continuation of the lever tool is pivotable about the pivot bearing opening as far as into the receiving means, preferably without contacting the tool holder and pressing it away directly as a result. 
     Over and above this, as already explained, the present invention relates to a groove insert for fixing in a tool holder according to the invention. The groove insert has two opposite ends, where a front surface which forms a main free face extends on one end and a rear surface extends on the opposite end. Over and above this, there is a top surface, a bottom surface as well as lateral faces. The main cutting edge is formed between the front surface and the top surface, where a holding structure, which is convex in cross section and is in particular trapezoidal, is realized along the top, the bottom and the rear surface. Between the bottom surface and the rear surface there is a beveled working surface for the lever tool (beveled with reference to the side view). 
     The lever tool is applied with an own face, the alignment of which is able to be positioned in an optimized manner with respect to the direction of the introduction of force. Once, by pivoting the lever tool in the direction of the groove insert, the ejector continuation is moved in a preferred manner obliquely against the groove insert, an application on the rear surface is avoided. 
     Laterally between the working surface and the lateral faces in each case there can be a prism face which extends obliquely with respect to the rear surface, with respect to the working surface and with respect to the corresponding lateral faces, i.e. the corners of the groove insert are provided with a bevel in said region. On the one hand, said bevel reduces the volume of the groove insert which is expensive to produce, on the other hand, as a result the ejector continuation does not press against an edge or corner. 
     The groove insert according to the invention is not an indexable insert, correspondingly it also has only one main cutting edge. 
     Finally, the invention also relates to a groove cutting tool having a tool holder according to the invention and a groove insert which is insertable into the tool holder so as to be replaceable, in particular a groove insert according to the invention. 
     One embodiment of the invention provides that the groove cutting tool has a groove insert which has a working surface for the ejector continuation which extends substantially at right angles with respect to the path of movement of the ejector continuation prior to contacting the groove insert. Consequently, the force for ejecting is to be introduced into the groove cutting tool in as perpendicular a manner as possible. 
     The slot can extend in relation to the pivot bearing opening in such a manner that the ejector continuation, when moving from the insertion portion as far as up to contact with the groove insert, does not exert any expanding force onto the clamping jaw. 
     In addition, the pivot bearing opening as a longitudinal groove and the lever tool can be realized such that the ejector continuation, when moving out of the insertion portion as far as up to contact with the groove insert, executes a curved, in particular circular-segment-shaped path and/or extends along a linear path when moving along the expanding portion. According to one configuration of the invention, it is provided that the rake face follows the profile of the main lip. The resulting step-shaped geometry of the rake face has a positive effect on chip formation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the invention are produced from the following description and from the following drawings, to which reference is made and in which: 
         FIG. 1  shows a side view of a portion of the groove cutting tool according to the invention with a tool holder according to the invention and a groove insert according to the invention; 
         FIG. 2  shows a view of a detail of the groove cutting tool according to  FIG. 1  in the region of the groove insert; 
         FIG. 3  shows a side view of the tool holder according to the invention according to  FIG. 1 ; and 
         FIG. 4  shows a perspective view obliquely from behind of the groove insert according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a groove cutting tool, for example for groove cutting. The groove cutting tool includes a tool holder  10  which has a base  12 , also called a carrier, for a groove insert  14  as well as a clamping jaw  16  which is integrally formed on the base  12 . 
     In the case of the embodiment shown, the clamping jaw  16  does not have a passage opening for a clamping means in the form of a clamping screw, however this possibility would also be realizable as an alternative. 
     The clamping jaw  16  presses from above onto the cutting insert  14  and clamps said cutting insert between itself and the base  12 . 
     A so-called receiving means  18 , into which the cutting insert  14  penetrates and in which it is also held, is formed between the clamping jaw  16  and the base  12 . The receiving means is designated in  FIG. 3  by the reference  18 . 
     The receiving means  18  is defined by a top surface  20  of the base which forms a bottom edge of the receiving means  18 , a bottom surface  22  of the clamping jaw  16  as well as a rear surface  24  formed in the clamping jaw  16 . 
     As shown by way of dotted lines, the edge forming the top surface  20 , the bottom surface  22  and the rear surface  24  preferably has a profiled holding structure for forming positive locking with the cutting insert  14 , this being in the form of a groove, in particular a prism groove which can have a V-shaped or trapezoidal form. 
     Corresponding to the faces defining the groove in a lateral manner, the cutting insert shown in  FIG. 4  preferably has correspondingly inclined faces  26  such that flat contacts with the edge of the receiving means are produced. The convex holding profile on the top surface  28 , the rear surface  30  and the bottom surface  32  of the cutting insert  14  is shown in  FIG. 4 . In the region of the top surface  28 , as an alternative also the rear surface  30  and the bottom surface  32 , the profile can be provided with a depression  34  in order to save material. The holding structures produce a positive locking hold for the cutting insert  14  in the tool holder  10 . 
       FIG. 3  clearly shows that a slot  36  proceeds from the receiving means  18 , said slot together with the recess  18  separating the clamping jaw  16  in portions from the base  12 . 
     The slot  36  proceeds from the rear bottom end of the receiving means  18 , i.e. from the transition of the rear surface  24  to the top surface  20  of the base  12 . 
     The course of the slot can preferably be V-shaped according to  FIGS. 1 to 3 . 
     Different portions are produced in the slot  36  and these are explained in the simplest manner in conjunction with a lever tool  40  which is shown in  FIG. 1  by way of dot-dash lines. 
     The lever tool  40  is, for example, a type of rod/strip, from which an ejector continuation  42  as well as a bearing continuation  44 , which is at a spacing from said ejector continuation, protrudes laterally. The two continuations  42 ,  44  are preferably pins which are circular in cross section. 
     The tool holder  10  has at least one pivot bearing opening  46  in the region of the base  12 , two pivot bearing openings  46 ,  48 , which when viewed in the longitudinal direction of the cutting tool are located approximately at the same height but are axially offset with respect to one another, being provided in the exemplary embodiment shown. 
     In the case of the embodiment shown, which is, however, not to be understood as restricting, the pivot bearing opening  46  is realized as an elongated hole which extends transversely with respect to the longitudinal extension, whereas the pivot bearing opening  48  is a circular opening. 
     When the bearing continuation is inserted into the pivot bearing opening  46 , the ejector continuation  42  penetrates into the central insertion portion  50  of the slot  36  which is shown in  FIG. 1 . 
     The form of the slot  36  is realized such that the ejector continuation  42  is able to be inserted laterally exclusively into the insertion portion  50  without having to be pressed into the slot by expending any force. 
     Proceeding from the insertion portion  50 , an ejector portion  52  of the slot  36  extends as far as up to the receiving means  18 . In the opposite direction, the slot  36  merges from the insertion portion  50  into an expanding portion  54  which is preferably realized as a rectilinear path. 
     As can be found, above all, in  FIG. 2 , in each case a stop nose  56  or  58  is provided between the insertion portion  50  and the ejector portion  52  on the one hand and between the insertion portion  50  and the expanding portion  54 . The stop nose  56  which projects into the slot  36  is provided on the base-side edge of the slot  36  and the stop nose  58  is provided between the insertion portion  50  and the expanding portion  54  on the tool-holder-side edge of the slot  36 . 
     Both stop noses  56 ,  58  are preferably realized as rounded projections. The stop noses  56 ,  58  are provided for the purpose of forming a resistance for the ejector continuation  42  when said ejector continuation is to be moved from one portion into the adjacent portion  50  to  54 . Consequently, the lever tool is always in a clear position. 
     In the central position of the ejector continuation  42  shown in  FIG. 2 , said ejector continuation is held between the two stop noses  56 ,  58 . If the lever tool  40  is pivoted about the pivot bearing continuation  44  in the direction of the groove insert  14  (see arrow to the left in  FIG. 1 ), the ejector continuation  42  then slips easily upward on account of the stop nose  56  in order to lift the clamping jaw slightly and in order then to slide it over the stop nose  56 . The ejector continuation  42  does not then exert any more force directly onto the clamping jaw  16 , but rather is moved in the ejector portion  52  in order to press against the groove insert  14  and to push the same outward out of the support. 
     If the clamping jaw  16  is to be pressed upward in order to insert a new groove insert  14 , the ejector continuation  42  is pressed from the center position, the insertion portion  50 , into the expanding portion  54 , the ejector continuation  42  in this case having firstly to overcome the stop nose  58  by pressing the clamping jaw  16  far enough upward. In the case of this at least approximately linear movement, the pivot bearing continuation  44  is moved vertically inside the pivot bearing opening  46  which is realized as an elongated hole such that no pure pivoting movement of the lever tool  40  occurs. The ejector continuation  42  presses the stop nose  58  and consequently the clamping jaw  16  upward (see dot-dash line in  FIG. 2 ). 
     The width of the expanding portion  54  is reduced in the direction toward the bottom  60  of the slot  36 . As a consequence, the deeper the ejector continuation  42  is pressed into the expanding portion  54 , the wider the receiving means  18  is opened. 
     In order to achieve a lever action which is better for some situations, the lever tool  40  can also be inserted into the pivot bearing opening  48 . As can be seen in  FIG. 2 , the V-shaped slot  36  has a deepest region in which the insertion portion  50  is located. 
     As already explained beforehand, the slot  36  proceeds from the bottom edge of the receiving means  18 , i.e. from the base-side edge (top surface  20  of the base  12 ). The groove which forms the holding structure on the tool holder  10  in the region of the base-side bottom edge and of the rear surface  24  (see  FIG. 3 ), merges into the slot  36 . 
     The groove insert  14  according to  FIG. 4 , which is optimized for the tool holder  10 , is explained in more detail below. The groove insert  14  has two opposite ends, a front surface forming a main free face  70  being present on one end and a rear surface  30  which has already been explained on the opposite end. Over and above this, there is the bottom surface  32  and the top surface  28 . A main cutting edge  74  is realized at the transition between the front surface and the top surface  72 . In a side view, i.e. when looking onto the lateral faces  76 , the groove insert is beveled between the bottom surface  32  and the rear surface  30  thus forming a working surface  78  for the ejector continuation  42 , said working surface abutting against the rear surface  30  and extending obliquely. 
     The alignment of the working surface  78  is directed in such a manner in relation to the tool holder  10  that the line of movement (see arrow to the left in  FIG. 1 ) of the ejector continuation  42  is substantially at right angles with respect to the working surface  78  when the ejector continuation  42  impacts against the cutting insert  14 . 
     The edge between the working surface  78  and the respective side wall  76  is also beveled, thus forming a prism face  80 . Said prism face  80  is inclined with respect to the rear surface  30 , with respect to the working surface  78  and with respect to the lateral faces  76 . 
     In the case of the embodiment shown, the groove insert is not realized as an indexable insert so that the length of the holding structures is as long as possible.