A tool for chip-breaking machining

Abstract: A milling tool comprises a number of peripheral recesses (5), each one of which accomodating on one hand a cartridge (6) with a seat for a detachable cutting insert (17), and on the other hand a clamping wedge (7) which is tightenable by means of a clamping screw (11). The clamping wedge (7) has a first, trailing bearing surface (19) for cooperation with a second, leading bearing surface (20) on the cartridge. At a radial distance from the first bearing surface (19) and angled in relation to it, is provided a secondary bearing surface (27) for clamping of the cutting insert (17). In a first step, the clamping wedge may be tightened only provisionally in and for the fixing of only the cartridge (6), and then it may also clamp the cutting insert by further tightening to an inner end position. Thus, the cutting insert may be replaced or indexed without the cartridge (6) or the clamping wedge (7) necessarily having to be removed.

Description: Technical Field of the Invention The present invention relates to a tool intended for chip-breaking machining, which tool comprises a body that is rotatable around a central geometrical axis, said body having a peripheral envelope surface in which one or several recesses being delimited by a bottom wall and leading and trailing walls is/are provided, which diverge outwardly from the bottom wall, each one of said recesses separately having the purpose of accomodating on one hand a cartridge with a cutting insert being provided in a seat in said cartridge, and on the other hand a clamping wedge intended for fixing the cartridge, said wedge being tightenable by means of a clamping screw in engagement with a threaded hole that ends in the bottom wall in the body, the trailing wall of the recess having a first serrations provided to cooperate with an analogous second serrations on a trailing side of the cartridge opposed to the cutting insert, while the leading wall of the recess is smooth in order to cooperate with an equally smooth leading surface of the clamping wedge, and a trailing bearing surface of the clamping wedge and a leading bearing surface of the cartridge both being smooth in order to, when in contact with each other, permit a substantially radial dislocation of the clamping wedge relative to the cartridge in connection with the fastening of the latter. In particular - although not exclusively - the invention relates to milling tools, e.g., square shoulder facemills, facemills, slitting cutters or the like. Prior Art A tool realized in the shape of a milling cutter of the type as generally described above, is previously known from EP 0548036 A1. In this case, the individual cartridge can be introduced into the appurtenant recess from either the front or the back of the tool body, the determination of the axial position of the cartridge relative to the recess being adjusted by means of a radially oriented pin provided on the lower side of the cartridge, which pin is arranged to engage into a depression formed in the bottom wall of the recess, said depression having a larger diameter than the pin. Furthermore, each individual cutting insert is fastened on the appurtenant cartridge by means of a headed screw that extends through a through-hole in the cutting insert and is tightened into a threaded hole in the cartridge. The fact that the construction includes not only a clamping wedge for fixing only the cartridge per se , but also a particular clamping screw for fixing the cutting insert on the cartridge, in practice this means that the tolerance chain between on the one hand the tool body and its axis of rotation, and on the other hand each one of the numerous cutting inserts, becomes long. Inter alia , this leads to a situation where the precision of the positioning of the cutting inserts relative to the tool body (which in practice should be less than 1/100 mm) may easily be lost or become unsatisfactory, e.g., when the cutting inserts are to be replaced or indexed, or when for any reason, the cartridge has to be dismounted and remounted. In addition thereto, precisely the work of fine-adjusting the cutting inserts and the appurtenant cartridges relative to the tool body is tedious and time-consuming; something that is particularly disturbing when the milling tool is to operate at high speeds of rotation and/or in tough materials, which give limited life of the cutting edges of the inserts and, thereby, necessitate frequent replacement or indexing of the cutting inserts. A tool according to the preamble of independent claim 1 is known through FR 2210125 A and US 2664617 A. Objects and Characteristics of the Invention The present invention aims at eliminating the above mentioned inconveniences of previously known tools of the type in question and creating an improved tool, in particular a milling tool. Thus, a primary object of the invention is to provide a tool with detachable cutting inserts which may be fixed in seats in appurtenant cartridges without other means than the clamping wedges that are used for the fixing of the cartridges in the peripheral recesses of the tool body. A further object is to provide a tool in which the individual cartridge as well as the appurtenant cutting insert are capable of, with ease, taking up exactly defined operative positions relative to the tool body in connection with the mounting of, on one hand, the cartridge in the recess and, on the other hand, the cutting insert in the cartridge seat. Another object is to create a tool with a good ability to withstand at least minor break-downs in connection with, e.g., instantaneous and abrupt impact and shock loads. In particular, the cartridge shall be capable of resisting such loads without being seriously damaged or dislocated from its basic position. Still another object of the present invention is to provide a tool particularly intended for milling purposes, which may work at very high speeds of rotation, e.g., up to the range of 20 000 to 30 000 rpm. One particular aspect of the invention aims at providing a tool whose cutting inserts are secured centrifugally in a reliable way, even when the tool is caused to rotate at very high speeds of rotation. According to the invention, at least the primary object is achieved by means of the features that are defined in the characterizing portion of claim 1. Advantageous embodiments of the invention are further defined in the dependent claims. Brief Description of the Appended Drawings In the drawings: Fig. 1 is a perspective exploded view showing a part of a tool according to the invention, more specifically in the form of a milling tool, a number of cartridges and cutting inserts belonging to the tool being illustrated at a distance from the tool body, Fig. 2 is a perspective view of an individual cutting insert which forms part of the tool, Fig. 3 is a further perspective view showing an alternative embodiment of the cutting insert, Fig. 4 is a partial, schematic side view showing a cartridge, a cutting insert and a clamping wedge in a first functional state, Fig. 5 is a side view corresponding to Fig. 4 showing said components in a second functional state, Fig. 6 is a third side view showing a third functional state, Fig. 7 to 9 are side views of the same type as in Fig. 4 to 6, but showing an alternative embodiment of the cutting insert, viz. the embodiment that is illustrated in Fig. 3, and Fig. 10 is a simplified planar view of a portion of an alternative embodiment of the tool according to the invention, viz. in the form of a slitting cutter. Detailed Description of Preferred Embodiments of the Invention In Fig. 1, reference numeral 1 designates in general a body in the shape of a milling cutter head which is rotatable around a central geometrical axis (not shown). In the example, the body 1 is delimited by a peripheral, envelope-like surface 2 that extends between opposed gable surfaces 3, 4, of which the former is constituted by a front side, in whose proximity the cutting inserts of the tool are located, while the latter is constituted by a rear side, to which a rotatable spindle or the like(not shown) is connected in a suitable manner. Outwardly diverging recesses 5, which have the purpose of accomodating on the one hand a cartridge 6, 6a, and on the other hand at least one clamping wedge 7 are formed in the envelope surface 2. Each individual recess 5 (see also Fig. 4 to 6) is delimited by a leading wall 8, a trailing wall 9 and a bottom wall generally designated 10. The clamping wedge 7 cooperates with, and is tightenable by, a screw 11 which is in engagement with a threaded hole 12 that leads to the bottom wall 10 of the recess 5. More specifically, the screw 11 is of the type that comprises both a right-hand thread and a left-hand thread, these threads being separated from each other via a waist portion. One of these threads engages with the hole 12 in the tool body, while the other thread engages with a threaded through-hole 13 in the clamping wedge 7. The two male threads on the screw 11 have a certain play relative to the female threads of the holes 12, 13. Thanks to the existence of double threads on the screws 11, it becomes possible to move the clamping wedge 7 in a way known per se that gives increased velocity relative to the body, e.g., with double velocity in comparison with one single thread in connection with a rotation of the screw in either direction of rotation. The trailing wall 9 of recess 5 has a first serrations generally designated 14 which is arranged to cooperate with an analogous, second serrations 15 on a trailing side of the cartridge 6. In this context it should be pointed out that the terms "leading" and "trailing" walls, respectively, relate to the direction of rotation of the tool, which is indicated by the arrow A. Thus, when seen in the direction of rotation of the tool, the serrations 15 are formed on that trailing side of the cartridge that is facing away from a leading side in which a seat 16 is provided for a cutting insert 17. The leading wall 8 of an individual recess 5 (see also Fig. 4 to 6) is (at least partly) smooth and suitably planar in order to cooperate with an equally smooth and planar leading surface 18 on the clamping wedge 7. A trailing bearing surface 19 on the clamping wedge 7 is equally smooth and planar in order to cooperate with a leading, planar and smooth bearing surface 20 on the cartridge 6. As a result of the fact that said surfaces 8, 18, 19 and 20 are smooth, the clamping wedge may be moved without any obstacles substantially radially relative to the tool body and the cartridge in connection with the clamping of the latter. Although the serrations 14, 15 are of known type, which is an advantage, it deserves mentioning that the same are generally formed of ridges that are separated by intermediate grooves. As may be seen in Fig. 1 in combination with, e.g., Fig. 4, the individual toothings or serrations thus comprises a set of elongated, straight and inter-parallel ridges which may engage in the grooves of the other serrations. Advantageously, both the ridges and the grooves have a triangular cross-sectional shape, the free crests of the ridges being topped so that the ridges do not touch the bottoms in the cooperating grooves when the serrations are brought into engagement with each other. This implies that each individual ridge in one of the serrations is wedged very firmly between a pair of adjacent ridges in the other serrations. In other terms, a plurality of wedge joints is obtained at the boundary between the cartridge and the tool body. In practice, the top angle between the flank surfaces of the individual ridge (and the corresponding angle between the side surfaces of the individual groove) may amount to about 65°. Advantageously - however not necessarily - the serrations 14 extend the whole way along the axial length of the recess 5, i.e., between the gable surfaces 3, 4, and the serrations 15 extend along the whole length of the cartridge 6. As far as the milling tool shown in the drawings has been described hereto, it is substantially known from EP 0548036 A1. To make sure, before the distinguishing features of the tool according to the invention are described more thoroughly, it should be pointed out that the two different embodiments of cutting inserts that are shown in Fig. 2 and 3 are illustrated simultaneously in Fig. 1. More specifically, the cutting insert 17 according to Fig. 2 is shown coupled with a cartridge 6 which in a certain respect differs from the two cartridges 6a that accomodate a cutting insert 17' of the type shown in Fig. 3. In practice, only cartridges with cutting inserts of one and the same uniform type are used on the milling tool, but due to space reasons it has been chosen to illustrate the two different types of cutting inserts and cartridges in one and the same drawing figure. Reference is now made to Fig. 2, 4, 5 and 6, which illustrate the invention as it is applied with the cartridge 6 shown to the left in Fig. 1. In this case, the cutting insert 17 is of a simple type, as far as it is delimited by substantially planar top and bottom sides 21, 22, and a number of oblique relief surfaces 23. Between the top side 21 and the individual relief surface 23 a cutting edge 24 is formed. The seat 16 in the cartridge 6 has of course a shape that is suited to the shape of the cutting insert. Thus, the seat is delimited by a planar bottom surface 25 and two side surfaces 26 extending perpendicularly to each other, which are inclined relative to the bottom wall 25 at the same angle as the angle between the relief surfaces 23 of the cutting insert and the bottom side 22. It is characteristic for the present invention that the clamping wedge 7, besides an inner portion 7' on which the before-mentioned, trailing bearing surface 19 is formed, comprises an outer part 7'' with a secondary bearing surface 27 which is dislocated backwards relative to the first-mentioned bearing surface 19. In other words, the secondary bearing surface 27 is situated behind an imaginary plane in the straight extension of the surface 19. Moreover, the leading bearing surface 20 on the cartridge 6 is formed on an inner part 6' of the cartridge, being located radially inside the seat 16. The bearing surface 20 is inclined at a certain, restricted angle relative to the top surface 21 of the cutting insert and the bottom surface 25 of the seat, respectively. In Fig. 6, according to which the cartridge as well as the cutting insert are shown in a fixed state, α designates an angle between, on the one hand the leading wall 8 of the recess 5 and on the other hand the top surface 21 of the cutting insert. In this state, the bearing surface 20 is parallel to the wall 8, of which follows that the angle of obliquity between the bearing surface 20 and the bottom surface 25 of the seat is one and the same as the angle α. According to the concrete practical example, this angle amounts to 12°. In practice, the angle α may vary, but should lie within the range 8 to 25°, suitably 10-20° and preferably 11-15°. The secondary abutment surface 27 on the clamping wedge 7 also extends at a certain, restricted angle to the trailing bearing surface 19, viz. at said angle α. At its radial outer edge, the leading abutment surface 20 of the cartridge 6 transposes into an oblique chamfer surface 28, along which an inner end portion 29 of the clamping wedge may slide in connection with its introduction into the space between the cartridge and the leading wall 8 of the recess. Advantageously, this inner end portion 29 is also formed with a chamfer surface 30 that is inclined at an acute angle relative to the rear bearing surface 19 of the clamping wedge. In Fig. 4, the clamping wedge 7 is shown in a non-tightened state. A geometrical central line is designated B, which in the state according to Fig. 4 is common for the screw 11 and the two threaded holes 12, 13 in the tool body and the clamping wedge, respectively. In this state, the front surface 18 of the clamping wedge is somewhat inclined relative to the leading wall 8 of the recess, more specifically at an angle designated β. In practice, the angle β may amount to about 3°. The function of the invention should be evident from a comparison between Fig. 4, 5 and 6. In the state as shown in Fig. 4, the cutting insert 7 is separated from the cartridge 6, and the cartridge is inserted into the recess 5 without being influenced by the clamping wedge 7, which however, in its turn, is mounted on the screw 11 and kept fastened relative to the body by the fact that the inner thread of the screw is provisionally tightened in the hole 12. By tightening the screw 11 (which may be done from the outside of the clamping wedge by means of, e.g., a hexagon key), in a first step the clamping wedge may be moved to the position that is shown in Fig. 5. Here, the clamping wedge has been pulled in so far that the trailing bearing surface 19 of the clamping wedge has abutted the leading bearing surface 20 of the cartridge, after the two chamfer surfaces 28, 30 having slid along each other and passed each other. In connection with the moment when the chamfer surface 30 passes the chamfer surface 28, a wedging effect is achieved that brings the serration 15 of the cartridge into a distinct engagement with the serration 14 of the tool body. At the same time, the clamping wedge is brought to turn anti-clockwise around the fulcrum that is created by the linear edge 31 between the wall 8 and a vaulted surface 32 between the recess 5 and the envelope surface 2 of the tool body. More specifically, the clamping wedge is forced to turn in such a way that its leading surface 18 is laid with complete surface contact against the leading wall 8 of the recess. It is true that this requires that the geometrical central axis for the threaded hole 13 in the clamping wedge, said axis being designated C in Fig. 5, need be turned by β° relative to the central axis B for the threaded hole 12, but in practice this angular change may very well be accomodated by the previously mentioned play between the male threads of the screw 11 and the female threads of the holes 12, 13. When the clamping wedge 7 has taken its position as shown in Fig. 5, the cartridge per se is fixed in a reliable way by the wedge joint between the serrations 14, 15. However, the cutting insert 17 is still freely movable into and out of the seat 16, in that the distance between the secondary bearing surface 27 and the seat bottom 25 is somewhat larger than the thickness of the cutting insert. In practice, this dimensional difference, which in Fig. 5 is designated D, amounts to 0,2 to 0,4 mm, depending on the overall geometry of the construction. In a concluding, third step that is shown in Fig. 6, the screw 11 and the clamping wedge 7 are finally tightened. Thereby, the secondary bearing surface 27 on the clamping wedge will be gradually moved radially inwards relative to the cutting insert, in order to be finally pressed and wedged against the top side 21 of the cutting insert. In this state, the clamping wedge thus fixes not only the cartridge 6 but also the cutting insert 17. In connection with a change or indexing of the cutting insert 17, this may be quickly and easily detached from the cartridge by the simple measure of screwing out the screw and the clamping wedge a bit, to the position which is shown in Fig. 5 and in which the secondary bearing surface 27 is distanced from the top side of the cutting insert. In this state, the cartridge 6 is still reliably fixed in the appurtenant recess; more specifically by the fact that the clamping wedge still presses the cartridge by a force resultant R (see Fig. 6) that hits the serration 14 at a level outside its innermost ridge. Being able to utilize one and the same means, namely the clamping wedge, for fixing both the cartridge and the cutting insert, without any necessity of detaching and remounting the cartridge in connection with the removal of the cutting insert from the seat, is a considerable advantage in connection with the practical use of the tool, on the one hand, in view of the fact that the risk of tolerance errors is reduced, and on the other hand in view of the fact that the changing and indexing of the cutting insert are simplified. Another advantage of the invention is that the point of contact between the bearing surfaces 19, 20 of the clamping wedge and the cartridge form an abutment that is deeply located in the appurtenant recess, which abutment effectively counteracts possible tendencies of the cartridge and the cutting insert to tip in connection with situatins when the cutting insert is exposed to large tangential forces. The contact place deeply located in the recess between the bearing surfaces 19, 20 also brings about possibilities to shape the clamping wedge with a limited radial height. In other words, the outwardly facing surface of the clamping wedge may be placed relatively deeply within the recess in relation to the operative cutting edge of the cutting insert, while attaining a large space for chip removal adjacent to the top side of the cutting insert. In this context it should also be mentioned that the absence of clamping screws for the cutting insert improves the conditions for using cutting inserts of hard and brittle materials, such as ceramics. In practice, the tool construction illustrated in Fig. 1 permits the body 1, as such, to be made of aluminium or another light material, while the cartridges and clamping wedges may be made of steel or similar material. By giving the tool body, which is voluminous in comparison to the cartridges and the clamping wedges, a low weight, the total weight of the tool can be radically reduced; something that on one hand makes possible shorter acceleration and retardation times in connection with frequently repeated starting and stopping operations, and on the other hand makes possible an operative running with extremely high speeds of rotation, e.g., in the range of 20 000 to 30 000 rpm. In practice, the embodiment described in connection with Fig. 2, 4, 5 and 6 with a cutting insert with planar top and bottom sides, is suitable for running at medium high speeds of rotation, e.g., up to the range 10 000 to 20 000 rpm, but less so for extremely high speeds of rotation. In Fig. 3 and 7 to 9, and in the right part of Fig. 1, an embodiment of the invention is shown that may be advantageously used when it is desired to work with extra-ordinarily high rotation speeds. As may be seen in Fig. 3, this embodiment comprises a cutting insert 17', in whose top side 21 is formed a first depression 33 which has the shape of a substantially V-shaped groove that extends between two opposed edges of the insert. More specifically, the V-groove 33 is delimited by two planar side surfaces 33'. In Fig. 3 may also be seen how the V-groove 33 extends at a certain acute angle relative to two opposed cutting edges (for the simple reason that the milling tool is foreseen for square shoulder facemilling and has an overall geometry adapted for this purpose). Furthermore, a female recess generally designated 34 ends in the bottom surface 17'. In practice, this recess may be comparatively shallow and have a rotation-symmetrical shape, e.g., the basic shape of a frustum of a cone. As may be seen in the right part of Fig. 1 as well as in Fig. 7 to 9, a male means 35 is provided on the bottom side 25 of the cutting insert seat, for engagement with the female recess 34 in the cutting insert. In practice, the male means may have the same basic shape as the recess 34, but on all sides being smaller than the latter, so that the external side of the male means normally never comes in touch with the internal side of the female recess. In Fig. 7 to 9 may be seen how the secondary bearing surface 27 of the clamping wedge 7 in this case is provided on a special heel 36 on the clamping wedge. More specifically, on this heel 36 is provided a surface designated 37, which in turn extends at a certain, moderate angle to the trailing, primary bearing surface 19 of the clamping wedge. The angle designated λ in Fig. 9 between the individual side surface 33" in the V-groove 33 and the top surface 21, may amount to about 8°. The secondary bearing surface 27 is inclined relative to surface 37 by the same angle λ, i.e., by 8°. Of course, the angle λ may deviate from exactly 8°, but in practice it should lie within the range of 6 to 12°. When the clamping wedge 7 is finally tightened in the position according to Fig. 9, then the protrusion 35 and the heel 36 secure the cutting insert from the risk of being flung radially outwards from the seat by the centrifugal force. In its fixed position according to Fig. 9, the cutting insert is held clamped by means of the clamping wedge 7 according to previously generally described ways, although with the difference that the male heel 36 mechanically engages into the female depression in the form of the V-groove 33. However, in this state the protrusion 35 is normally inactive, in that the same lacks contact with the internal side of the recess 34. Only in an extreme case, would the protrusion 35 become active, viz. if the cutting insert during work at very high speeds of rotation would be submitted to shock impacts and/or an extra-ordinarily large centrifugal forces. In these cases, the protrusion guarantees that the cutting insert does not leave the seat, even if the side surface in question in the V-groove would tend to slide relative to the secondary bearing surface 27. In the embodiment with a centrifugally secured cutting insert according to Fig. 7 to 9, the cutting insert must be distanced by a considerable distance from the bottom surface of the seat in connection with replacing or indexing cutting inserts. This means that also the clamping wedge 7 has to be removed from the proximity of the cutting insert. For this reason, the clamping wedge 7 is provided with the support of a second clamping wedge 38, which is placed in the axial extension of the first-mentioned clamping wedge and which has the single purpose of fixing the cartridge. This second clamping wedge 38 is tightenable by means of a second double-threaded screw 39. In their active, finally tightened states, the two clamping wedges 7, 38 cooperate to jointly clamp the cartridge, whereas, however, only the clamping wedge 7 simultaneously also clamps the cutting insert into the seat of the cartridge. When the cutting insert is to be removed from the cartridge, the first clamping wedge 7 may be removed or screwed out to such an extent that the cutting insert may be removed from the seat, without the cartridge being displaced from its given adjusted position, in that the second clamping wedge 38 then still keeps the serrations 14, 15 in unaltered engagement with each other. According to a preferred embodiment of the invention, the bottom wall 10 of the individual recess 5 is divided into at least two part walls 10', 10", which are located at different radial distances from the rotation axis of the tool body, and which are separated by a first abutment surface 40 facing the cutting insert. This abutment surface 40 extends at an angle, suitably perpendicularly, to the serrations 14 in the trailing wall of the recess, and has the purpose of cooperating with an analogous second abutment wall 41 on the cartridge 6a. It also extends perpendicularly to the part wall 10'. This second abutment surface 41 extends correspondingly, suitably perpendicularly to the serrations 15 of the cartridge (in fact, perpendicularly to the axial extension of the ridges and grooves). When the cartridge is mounted into the recess, its location can be determined, in a simple manner, in a predetermined basic position merely by the simple measure of bringing the serrations 14, 15 to slide along each other till the abutment surface 41 abuts the abutment surface 40. Since both the abutment surface 40 on the tool body (also in this case the latter is made of aluminum) and the abutment surface 41 on the cartridge (usually of steel), may be made with high accuracy, the cartridge may in a simple manner be mounted into an exactly defined basic adjustment position, that is easily repeatable and uniform for all cartridges and recesses on the tool. The tool may be provided with means for enabling a fine adjustment of the cartridge relative to the body. In Fig. 1 such a means is exemplified in the form of a separate key 42 that is insertable into a through, cylindrical bore 43 in the cartridge. The key 42 comprises a cylindrically shaped shaft 44 which at a free end transposes into an eccentric body 45 that shall be brought into engagement with an elongated depression 46 in the bottom part wall 10''. Therefore, by turning the key, fine axial movements relative to the tool body may be conferred to the cartridge, while the two clamping wedges are moderately tightened. The ability to make fine-adjustments to the position of the cartridge, e.g., to thousandths or hundredths of a millimeter, is important on one hand in such cases when tolerance deviations occur in connection with manufacture, and on the other hand in such cases when the cartridge unexpectadly would have been dislocated from its basic adjustement position, e.g., due to shock impacts. For the sake of completeness, it should be mentioned that the part wall 10" radially protruding relative to the bottom part wall 10', in its turn transposes into an angularly broken part wall 10', in which a threaded hole 47 for the clamping screw 39 ends. This part wall 10''' extends perpendicularly to the leading wall 8 of the recess, at the same time as the part wall 10'' also extends perpendicularly to the trailing wall 9 provided with the serrations 14, which wall extends at an acute angle (e.g., within the range 25 to 35°) to the leading wall 8. In Fig. 10 is indicated schematically how the invention may advantageously also be applied on slitting cutters of the type that comprises an extremely thin, plate-shaped tool body 1. In this case, one single clamping wedge 7 may simultaneously hold a cartridge 6 as well as a cutting insert 17, it being possible according to the previously described manner to clamp and maintain the cartridge in its adjusted position also when the cutting insert is to be replaced or indexed. Feasible Modifications of the Invention The invention is not limited solely to the embodiments as described and shown in the drawings. Thus, the cutting inserts and the appurtenant seats in the cartridge may have other arbitrary basic shapes than just square or generally quadrilateral. The cutting inserts may, for instance, have a round or arbitrarily polygonal basic shape. Although the invention has been exemplified specifically in connection with a milling tool, it may also be applied to other types of rotating tools for chip-breaking machining of the kind that makes use of cartridges with detachable cutting inserts.

Claims: A tool intended for chip-breaking machining comprising a body (1) that is rotatable around a central geometrical axis, said body having a peripheral envelope surface (2) in which is/are provided one or several recesses (5) being delimited by a bottom wall (10) and leading and trailing walls (8, 9), each one of which recesses separately having the purpose of accomodating on the one hand a cartridge (6) with a cutting insert (17) being provided in a seat (16) in said cartridge, and on the other hand a clamping wedge (7) intended for fixing the cartridge, said wedge being tightenable by means of a clamping screw (11) in engagement with a threaded hole (12) that ends in the bottom wall in the body (1), the leading wall (8) of the recess being smooth in order to cooperate with an equally smooth leading surface (18) of the clamping wedge (7), and a trailing bearing surface (19) of the clamping wedge and a leading bearing surface (20) of the cartridge (6) both being smooth in order to, when in contact with each other, permit a substantially radial dislocation of the clamping wedge relative to the cartridge in connection with the fastening of the latter, said leading and trailing surfaces (18, 19) of the clamping wedge (7) being parallel to each other, the clamping wedge (7) besides an inner part (7'), on which said trailing bearing surface (19) is provided, comprising an outer part (7") with a secondary bearing surface (27), being dislocated backwards relative to said trailing bearing surface (19), the inner part (7') of the clamping wedge being insertable into the space between the bearing surface (20) of the cartridge and the leading wall (8) of the recess by tightening of the clamping screw (11), in order to be capable of taking on one hand a provisional outer position in which the cartridge (6) is fixed, without the secondary bearing surface (27) of the clamping wedge being pressed against the cutting insert (17), and on the other hand an inner, finally tightened end position in which the secondary bearing surface (27) of the clamping wedge is pressed against the top surface (21) of the cutting insert, while fixing it into the appurtenant seat (16), characterized in that said leading and trailing walls (8, 9) diverge outwardly from the bottom wall (10), in that the trailing wall (9) of the recess (5) has first serrations (14) provided to cooperate with analogous second serrations (15) on a trailing side of the cartridge (6) opposed to the cutting insert, in that the leading bearing surface (20) on the cartridge is provided on an inner part of the cartridge located inside the seat (16) and its cutting insert (17) and extends parallel to the leading wall (8) of said recess when said first and second serrations (14, 15) are fixedly interengaged, and in that the cartridge (6) is fixed in said outer provisional position by said first and second serrations (14, 15) engaging into each other. Tool according to claim 1, characterized in, that the leading bearing surface (20) of the cartridge transposes into an oblique chamfer surface (28) along which an inner end portion (29) adjacent to the inner bearing surface (19) of the clamping wedge is slidable in connection with the introduction of the clamping wedge into said space between the cartridge (6) and the leading wall (8) of the recess (5). Tool according to claim 2, characterized in, that also the inner end edge portion (29) of the clamping wedge is formed with a chamfer surface (30) that is oblique relative to said inner bearing surface (19). Tool according to any of the preceding claims, characterized in, that the secondary bearing surface (27) of the clamping wedge is oblique relative to the inner bearing surface (19) at an angle within the range 8 to 25°, suitably 10 to 20° and preferably 11 to 15°. Tool according to any of the preceding claims, characterized in, that the secondary bearing surface (27) of the clamping wedge (7) is provided on a heel (36) protruding from the trailing side of the outer part (7") of the clamping wedge and cooperates with one of two side surfaces (33') in a groove (33) with a V-shaped cross-section in the top surface (21) of the cutting insert. Tool according to any of the preceding claims, characterized in, that the clamping screw (11) comprises a right-hand thread as well as a left-hand thread separated from the former, of which threads one is in engagement with a threaded hole (13) in the clamping wedge (7) and the other with the threaded hole (12) in the tool body (1), the two male threads having a certain relative play relative to the cooperating female threads, and that the clamping wedge (7), when tightening the clamping screw (11), is linearly movable along the geometrical central axis (B) of the threaded hole (12) in the tool body up to a certain point where the trailing inner bearing surface (19) of the clamping wedge comes in contact with the leading bearing surface (20) of the cartridge, whereby the clamping wedge is forced to turn inwards/forwards under a pressing of the leading surface (18) of the clamping wedge into a complete surface contact with the leading wall (8) of the recess (5), said turning movements of the clamping wedge being accomodated by said thread play, and the inner part (7') of the clamping wedge being axially movable from said contact point to its inner, cutting insert-fixing end position thanks to the parallelity between the inner bearing surface (20) of the cartridge and the leading wall (8) of the recess. Tool according to any of the preceding claims, characterized in, that each one of said serrations (14, 15) comprises a set of elongated, straight and inter-parallel ridges that are separated by intermediate grooves, the ridges as well as the grooves having a triangular cross-sectional shape and the free crests of the ridges being topped so that the ridges do not reach the bottoms in the cooperating grooves when the serrations are brought into engagement with each other. Tool according to any of the preceding claims, characterized in, that the bottom wall (10) of the individual recess (5) is divided into at least two part walls (10', 10'') at different radial distances from the axis of rotation, which walls are separated by a first abutment surface (40) facing the cutting insert (17), said abutment surface extending at an angle to the serration (14) in the trailing wall (9) of the recess and having the purpose of cooperating with an analogous, second abutment surface (41) on the cartridge (6), more specifically in order to hold the cartridge and the appurtenant cutting insert in an exactly defined basic adjustement position relative to the tool body (1). Tool according to any of the preceding claims, characterized in, that on the top side (21) of the individual cutting insert (17) a first depression (33) for receiving a heel (36) of the clamping wedge carrying the secondary bearing surface (27) is provided, and that in the bottom side (22) of the cutting insert a female recess (34) and/or a male means for cooperation with a suitable male means and/or a female recess in the bottom surface (25) of the seat (16) is provided, all this in order to secure centrifugally the cutting insert in the seat.

Inventors: QVARTH INGEMAR, QVARTH, INGEMAR
Applicants: SANDVIK AB, SANDVIK AKTIEBOLAG
Application year: 1999
Main classification: B23C5
IPC codes: B23C5