Abstract:
A tool for chip removing machining includes a holder and a cutting insert removably mounted therein. The insert includes a shaft having opposite ends and defining a first longitudinal center line. A cutting head projects integrally from at least one end of the shaft. The cutting head includes a cutting edge forming an angle of 45° with the first longitudinal center line. Alternatively, or additionally, the cutting head defines a second longitudinal center line forming an angle of 45° with the first longitudinal center line.

Description:
RELATED INVENTION  
       [0001]    This application claims priority under 35 U.S.C. §§ 119 and/or 365 to Patent Application No. 0000689-0 filed in Sweden on Mar. 2, 2000, the entire content of which is hereby incorporated by reference.  
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to a tool for chip removing machining, whereby the tool comprises a holder as well as a cutting insert fixed in the holder, which cutting insert has at least a first cutting head having a first major cutting edge. The invention also relates separately to the cutting insert included in the tool.  
         PRIOR ART  
         [0003]    A machining tool, which has a cutting insert that, in turn, has a cutting head angled in relation to a mounting shaft, is previously known from WO 95/29781. A characteristic feature of this cutting insert is that the minor cutting edges of the cutting head are not parallel to each other, making it possible for the cutting insert to be fed in two different directions, which are parallel to the respective minor cutting edge. It should also be observed in this context that the major cutting edge is perpendicular to the longitudinal direction of the shaft.  
           [0004]    A cutting insert is previously known from EP 0 385 280, which has a cutting head as well as a mounting shaft, whereby the cutting head is hook-shaped with respect to the shaft. According to a preferred embodiment, the cutting head has an extension, which is at a right angle to the axis of the shaft. Also an alternative embodiment shown in the above-mentioned WO 95/29781 has a design which in principal is corresponding to that of EP 0 385 280.  
         SUMMARY OF THE INVENTION  
         [0005]    A primary aim of the present invention is to provide a tool and a cutting insert of the kind defined in the introduction, whereby a small number of different holders and cutting inserts, respectively, make possible a large number of possible combinations as regards cutting operations which may be made with the tool according to the present invention. That is, many different orientations of inserts relative to holders are made possible by a relatively small number of different holders and inserts.  
           [0006]    Another aim of the tool and the cutting insert, respectively, according to the present invention is to improve accessibility in different cutting operations in comparison with known tools and known cutting inserts, respectively, having the corresponding outer dimensions.  
           [0007]    The present invention relates to a tool for chip removing machining comprising a holder and a cutting insert removably mounting therein. The insert comprises a shaft having opposite ends and defining a first longitudinal center line. A cutting head projects integrally from at least one end of the shaft. The cutting head defines a second longitudinal center line forming an angle of 45° with the first longitudinal center line. Alternatively, or additionally, the cutting head includes a cutting edge forming an angle of 45° with the first longitudinal center line.  
           [0008]    The present invention also pertains to the cutting insert per se.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The objects and advantages of the invention will become apparent from the following detailed description of preferred embodiments thereof in connection with the accompanying drawings, in which like numerals designate like elements, and in which:  
         [0010]    [0010]FIG. 1 shows in plan view a first embodiment of a cutting insert according to the present invention;  
         [0011]    [0011]FIG. 2 shows a plan view of a second embodiment of a cutting insert according to the invention;  
         [0012]    [0012]FIG. 3 shows a plan view of a third embodiment of a cutting insert according to the invention;  
         [0013]    [0013]FIG. 4 shows a plan view of a fourth embodiment of a cutting insert according to the invention;  
         [0014]    [0014]FIG. 5 shows a plan view of a fifth embodiment of a cutting insert according to the invention;  
         [0015]    [0015]FIG. 6 shows a plan view of a part of a tool according to the present invention;  
         [0016]    [0016]FIG. 7 shows a side view of the tool according to FIG. 6;  
         [0017]    [0017]FIG. 8 shows a perspective view of the tool according to FIG. 6;  
         [0018]    [0018]FIG. 9 shows a plan view of the tool according to FIG. 6, whereby the clamp for reasons of clarity has been removed, and a cutting insert according to FIG. 4 is mounted therein;  
         [0019]    [0019]FIG. 10 shows a plan view of the tool according to FIG. 6, whereby the clamp for reasons of clarity has been removed and a cutting insert according to FIG. 2 is mounted therein;  
         [0020]    [0020]FIG. 11 shows a perspective view of the tool according to FIG. 10;  
         [0021]    [0021]FIG. 12 shows a feasible type of machining performed by a cutting insert according to the present invention;  
         [0022]    [0022]FIG. 13 shows a plan view of an additional cutting insert according to the present invention; and  
         [0023]    [0023]FIG. 14 shows an assortment of cutting inserts, both according to the present invention and prior art, and holders, whereby different types of machining which respective cutting inserts may carry out are also indicated.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0024]    In FIGS.  1 - 5 , a respective number of cutting inserts  1   a ,  1   b ,  1   c ,  1   d ,  1   e  are shown, which constitute cutting inserts according to the present invention. Each one of the cutting inserts la-le comprises a shaft  3   a ,  3   b ,  3   c ,  3   d ,  3   e  as well as at least a first cutting head  5   a ,  5   b ,  5   c ,  5   d ,  5   e  projecting from an end of the shaft, which cutting head has a first major cutting edge  6   a ,  6   b ,  6   c ,  6   d ,  6   e . What generally distinguishes a cutting insert  1   a - 1   e  according to the present invention is that, as seen in a plan view, a longitudinal center line C 2  of the cutting head  5   a ,  5   b ,  5   c ,  5   d ,  5   e  forms an angle of 45° with the longitudinal center line Cl of the shaft  3   a - 3   e . Furthermore, a line L through the cutting edge  6   a - 6   e  of the first cutting head  5   a - 5   e  forms an angle of 45° with the longitudinal center line Cl of the shaft  3   a - 3   e.    
         [0025]    The cutting inserts  1   a ,  1   b ,  1   c  are provided with a second angled cutting head  5 ′ a ,  5 ′ b ,  5 ′ c  at the opposite end of the shaft  3   a ,  3   b ,  3   c . These second cutting heads  5 ′ a ,  5 ′ b ,  5 ′ c  also have a major cutting edge  6 ′ a ,  6 ′ b ,  6 ′ c . The cutting inserts  1   a  and  1   b  illustrated in FIGS. 1 and 2 are mirror-inverted in relation to each other, whereby the cutting heads  5   a ,  5 ′ a ;  5   b ,  5 ′ b  on each of the cutting inserts  1   a ,  1   b  are angled in opposite parallel directions from the appurtenant shaft  3   a ,  3   b.    
         [0026]    The cutting insert  1   c  illustrated in FIG. 3 also has two cutting heads  5   c  and  5 ′ c , whereby said cutting heads  5   c ,  5 ′ c  are angled to the same direction side of the appurtenant shaft  3   c . In the corresponding way as for the first cutting heads  5   a - 5   e , a line L′ through the second major cutting edges  6 ′ a ,  6 ′ b ,  6 ′ c  forms an angle of 45° with the longitudinal center line Cl of the shaft  3   a ,  3   b ,  3   c . A longitudinal center line C 3  of the cutting head  5 ′ a ,  5 ′ b ,  5 ′ c  forms an angle of 45° with the longitudinal center line C 1  of the shaft  3   a - 3   e . Thus, the two cutting heads  5   c ,  5 ′ c  form a 90° angle to one another. In the plan views according to FIGS.  1 - 5 , the major cutting edges  6   a ,  6 ′ a ,  6   b ,  6 ′ b ,  6   c ,  6 ′ c ,  6   d ,  6   e  are parallel to the plane of the paper.  
         [0027]    The tool according to FIGS.  6 - 8  comprises a holder  10 , in which an insert seat for receiving a cutting insert  1   a ,  1   b ,  1   c ,  1   d  or  1   e  according to the present invention is arranged. In particular, the insert  1   c  or  1   d  is shown in FIGS.  6 - 8 . A clamp  11  is attached on top of the cutting insert, said clamp  10  being fixed in the holder by means of a screw  12 . By tightening the screw  12 , the clamp  10  will fix the cutting insert in the appurtenant insert seat in the holder  10 .  
         [0028]    In FIG. 9, for reasons of clarity, the holder  10  is shown without clamp  11 . In that connection, it is seen that the insert seat of the holder  10  has an end stop in the form of a pin  13 . As is seen in FIG. 9. the end of the shaft  3   d  disposed opposite from the cutting head abuts against said pin  13 . The design of the end stop as a pin  13  entails the advantage that said end stop also may be used as a stop for cutting inserts which have cutting heads at both ends of the shaft, as will become apparent.  
         [0029]    It will be appreciated that the insert seat of the holder includes a seat surface  20  on which the insert is placed. The pin  13  has a cylindrical stop surface  26  against which an end of the insert shaft abuts. The surface  26  defines a center axis extending perpendicular to the seat surface  20 .  
         [0030]    In FIGS. 10 and 11, where the clamp, for reasons of clarity, is omitted, it is shown how a cutting insert  1   b  having cutting heads  5   b  and  5 ′ b  at both ends of the shaft  3   b  may be attached in the holder  10 . As is most clearly seen in FIG. 10, the insert seat in the holder  10  is formed with a recess  14  extending alongside the pin  14  in a direction transversely of the center axis of the insert shaft for receiving the non-active cutting head  5 ′ b , i.e., the cutting head which is not in an active position. Also in this case, the pin  13  acts as an end stop for the cutting insert  1   b , in that the pin  13  cooperates with one of the side surfaces of the non-active cutting head  5 ′ b  of the cutting insert  1   b . Thanks to the shaft  3   b  being fixed laterally in the insert seat of the holder  10 , abutment of said side surface against the pin  13  will ensure that the cutting insert  1   b  is secured against displacement in the longitudinal direction of the shaft  3   b  towards the non-active cutting head  5 ′ b . That is, cooperation between the side surface of the non-active cutting head  5 ′ b  and the pin  13  constitutes an end stop for the cutting insert  1   b . Said end stop works in the corresponding way also when the insert  1   b  is reversed such that the cutting heads  5   b  and  5 ′ b  change places with each other.  
         [0031]    The use of a cutting insert  1   d ′ according to the present invention for internal turning is shown in FIG. 12. Said cutting insert  1   d ′ constitutes a variant of the cutting insert  1   d  according to FIG. 4, whereby one of the side edges of the cutting head  5   d ′ of the cutting insert  1   d ′ constitutes a major cutting edge  15 , which carries out machining of the work piece. The edge  6   d ′ corresponding to the major cutting edge  6   d  of the cutting insert  1   d  defines, in that connection, the clearance angle a marked in FIG. 12. As is seen in FIG. 12, also in this embodiment, a line L through the major cutting edge  15  forms an angle of 45° with the longitudinal center line C 1  of the shaft  3   d ′.  
         [0032]    The cutting insert  1   b ″ according to the present invention illustrated in FIG. 13 differs principally from the cutting insert  1   b  according to FIG. 2 in that as seen in plan view the cutting heads  5   b ″ and  5 ′ b ″ have continuously curved cutting edges  6   b ″,  6 ′ b ″, more precisely a cutting edge which has a circular shape as seen in plan view. As for the angling of the cutting heads  5   b ″,  5 ′ b ″ in relation to the shaft  3   b ″, each of the longitudinal center lines C 2  and C 3  of the respective cutting heads  5   b ″ and  5 ′ b ″ form an angle of 45° with the longitudinal center line Cl of the shaft  3   b ″.  
         [0033]    In FIG. 14, a number of cutting inserts and a number of holders are shown, whereby the cutting inserts  1   a - 1   e  constitute cutting inserts according to the present invention while the cutting inserts S 1  represent prior art inserts. The holders  10  and  10 ′ have different rear shapes (not shown), whereby the holder  10  is intended for external tools while the holder  10 ′, which for instance consists of a bar, is intended for internal tools. The cutting inserts may arbitrarily be combined with any one of the holders  10 ,  10 ′.  
         [0034]    In FIG. 14, a workpiece  16  is also shown, in which different types of machining operations are marked, the majority of which advantageously may be made by means of a tool according to the present invention.  
         [0035]    Feasible Modifications of the Invention  
         [0036]    The detailed design of the cutting insert according to the present invention may naturally be varied within the scope of the invention. As is seen in the embodiments accounted for above, the cutting heads may thus have different designs as regards the position of the major cutting edges but also as regards surfaces for chip breaking and clearance. Also the design of the shaft may be varied, for instance depending on the design of the insert seat and the clamping members of the holder.