EP2358492A1

EP2358492A1 - Tool for chip removal machining, with removable inserts

Info

Publication number: EP2358492A1
Application number: EP09756737A
Authority: EP
Inventors: Massimo Bedon; Stefano Renzoni
Original assignee: Delta Tools Srl
Current assignee: Delta Tools Srl
Priority date: 2008-11-24
Filing date: 2009-11-20
Publication date: 2011-08-24
Also published as: WO2010057993A1; ITGE20080098A1

Abstract

Tool for chip removal machining, particularly for metals, comprising an insert holding rod (1) a predetermined number of inserts (2, 3) being removably attachable to the working end thereof, each of which having or forming one or more cutting edges (402, 103). According to the invention, the tool has at least four cutting edges (103, 402) provided in pairs on one plate or slab-like insert (2, 3) respectively, cutting edges (103, 402) of each pair being provided at opposite ends of the corresponding insert (2, 3) with reference to a median axis of the insert (2, 3). Said two inserts (2, 3) are provided with means (302, 203) for being mutually snap fitted in a cross-like position and the insert holding rod (1) is provided with diametral cuts or notches (301, 401) in a cross-like orientation correspondingly to the relative orientation of said two inserts (2, 3) and which have an axial extension corresponding to the axial extension of the two inserts (2, 3) and which cuts (301, 401) are open at the front side (21) and shell (101) of the insert holding rod (1), such that the two previously coupled inserts (2, 3) are put together into cuts (301, 401) of the insert holding rod (1) by a translation in the axial direction of the insert holding rod (1).

Description

DELTA TOOLS SRL.

TOOL FOR CHIP REMOVAL MACHINING, WITH REMOVABLE

INSERTS .

The present invention relates to a tool for chip removal machining, particularly for metals, according to the characteristics of the preamble of the first claim.

Particular embodiments of said tool fall within the concept of milling cutter.

Milling cutters are chip removal tools generally composed of a rod, which is rotated around its longitudinal axis and which rod holds inserts that in turn form or hold cutting edges by means of which the workpiece is excavated. They have to bear stresses generated during the machining and therefore they have to show suitable mechanical characteristics such as for example a high strength, a high wear resistance and a low friction coefficient. Milling cutters are known to be provided with several configurations which are different from one another in the geometry and/or arrangement of inserts and of relevant cutting edges with respect to the rod.

In some configurations the cutting edges can be obtained by shaping the rod and therefore they are as one-piece with the rod.

On the contrary other configurations provide the cutting edges to be formed of separate elements, so called inserts which can be applied on the rod in a removable and therefore replaceable manner when the cutting edges are worn.

The above mentioned configurations are known and widely used.

According to prior art, for example in patent US4729697, said milling cutters are generally composed of inserts holding cutting edges and which are fastened to the rod into suitable seats made in the rod. Typically the size of such inserts is therefore smaller than the diameter of the rod. They are fastened to the rod by means of different clamping and centering mechanisms. At least a screw is usually used which transversally passes through the plate or slab-like insert in order to clamp and center it in the proper position on the rod. Therefore in these configurations each insert with the corresponding cutting edge or edges is fastened to and centered in the rod within a dedicated fastening seat independently from the other ones .

The drawback of this type of configuration is that, as the diameter of the rod becomes smaller, the necessary provision of seats for mounting the inserts causes the rod to be mechanically weakened and therefore it is more and more complicated to produce systems able to meet mechanical requirements. Moroever the operation for independently clamping and centering each insert is time-consuming and it requires a high precision since drawbacks related to clearance in the positions of the cutting edges can be generated, which clearances combined together can lead to failures of the system. There are provided configurations having a milling head composed of a single insert composed of a plate or slab-like element which has a width substantially equal to the rod diameter, and which plate-like element is shaped such to have two diametrically opposite cutting edges as one-piece therewith.

Said cutting edges are particularly provided along one or more peripheral edges of the plate-like inserts and they extend often along the peripheral edges of the inserts protruding past the front side of the insert holding rod and/or past the peripheral shell surface of said insert holding rod and possibly also about the rounded corner area connecting said two edges .

Said plate-like insert has a transverse hole and it is fastened to the insert holding rod by means of a screw passing through said hole, said insert holding rod being provided with a cut, namely a transverse slot or notch which is longitudinal with respect to the axis of rotation of said rod, which cut receives a portion of the plate-like insert wherein the hole for the screw is provided. Even in this case, the hole has to be ground, and the screw, in addition to the clamping function, has also the important function of centering the insert with the corresponding cutting edges . That increases the complexity of the system and increases the risk of a wrong adjustment adversely affecting the performance of the milling cutter.

Moreover according to a further prior art example, such as described in DE 10 2006 009801 the plate or slab-like inserts are transversally arranged one upon the other by means of corresponding recesses provided between the cutting edges in a first insert and on the side opposite to the cutting edges in a second insert respectively . Such arrangement allows the two inserts to be engaged one upon the other by sliding the first insert with the recess arranged on the side free from cutting edges from the top into the recess of the second insert, which recess is provided on the side provided with the cutting edges.

Such arrangement does not allow the inserts to be clamped on the rod by means of screws .

In the case when inserts are desired to be clamped into a seat of the rod by means of a clamping screw, it would be necessary to increase the dimensions of the inserts, in particular the length of said plate-like inserts such to achieve an insert having such an area large enough to provide the hole for housing the clamping screw. This causes seats for fitting the inserts on the rod to have a high depth causing the rod structure to weaken at the end that will be in contact with the workpiece.

In addition, the bit reffered to in DE 10 2006 009801 is a bit used for drilling walls or stone and it is particularly suitable for percussion drills or hammer drills . Typically with this type of bits , precision tolerances are relatively high and therefore the problem of having a centering action in the order of hundredths of a millimeter for example of 0,01 mm does not exist as on the contrary it exists for bits or milling cutters used for drilling metals and in particular steel. The two cross-like arranged inserts are then fastened on the rod into the corresponding housing notches by welding or brazing or other similar means so the centering precision is not certainly such to guarantee tolerances as the ones indicated for the steel.

EP 0008972 provides the introduction of clamping screws but the two plates are not arranged in a cross- like arrangement and the screw has to perform the retaining action widthwise of the plate faces . Therefore due to the fact that abutment surfaces perpendicular or transversal to the plate faces cooperating with corresponding abutment surfaces of the seats housing them in the rod are not provided, the screw acts also for centering the two plates with reference to their position along the diametral plane of the rod parallel to the plate faces and perpendicular to the screw: therefore the screw has three functions and that is it clamps the plates in their seat within the rod, it absorbs stresses generated upon the use of the tool in the plane parallel to the plate faces and it guarantees plates to be properly centered with respect to the rod and therefore to the axis of rotation with a precision of hundredths of a millimeter. In addition to the necessary high precision grinding of the hole and of the screw since the screw has both a centering function and a function of bearing stresses transverse parallel to plate faces, it is necessary for the hole and the screw to have a particular dimension in order to guarantee a particular strength of the tool. In particular radial forces parallel to the plate surfaces have to be completely absorbed by the screw since no further abutment elements are provided between the rod and the plates with reference to said direction but without losses in the centering precision due to said stresses only on the screw.

The aim of the present invention is to overcome such prior art drawbacks by reducing the complexity of the system, by increasing the performance thereof and by making the replacement of the inserts more rapid and safe.

The invention achieves the above aims by providing a tool for chip removal machining, particularly for metals, according to the characteristics of the first claim. In particular the tool comprises an insert holding rod to which working end a predetermined number of inserts can be removably fastened, each one of which is formed of a plate or slab-like element and has at least a cutting edge along a perimetral edge and wherein said insert holding rod can be mechanically coupled to a powered shaft to receive a rotation about its longitudinal axis , said insert holding rod being provided with a seat for removably fastening said inserts, which seat is obtained in the body of the insert holding rod and with the insert or inserts mounted into said insert holding rod the cutting edges formed or provided on said inserts outwardly project therefrom, past the front surface and/or the side shell surface of said insert holding rod, there being further provided means for removably fastening and centering said inserts into said seat or seats and the tool being provided of at least four cutting edges arranged in pairs on one insert respectively, the cutting edges of each pair being provided at the opposite ends of the corresponding insert with reference to a median axis of the insert parallel to the axis of the insert holding rod with the insert mounted on said insert holding rod; said two inserts being provided with means for being mutually snap fitted in a cross-like position and the insert holding rod being provided with diametral cuts or notches in a cross-like orientation correspondingly to the relative orientation of said two inserts and which have an axial extension corresponding to the axial extension of the two inserts and which cuts are open at the front and shell side of the insert holding rod such that the two previously coupled inserts are introduced together into the cuts of the insert holding rod with a translation in the axial direction of the insert holding rod and they can be removably fastened in the limit insertion position wherein cutting edges at the opposite ends of the two inserts protrude for the predetermined amount from the front side and/or from the lateral shell of the insert holding rod.

The insert has at least four cutting edges arranged in pairs on one insert composed of a plate- like element respectively the cutting edges of each pair being provided at the opposite ends of said insert with reference to a median axis of the insert which median axis is parallel to the axis of the insert holding rod with the plate mounted on said rod, moreover said two at least inserts being provided with means for being mutually snap fitted in a cross-like position and the insert holding rod being provided with diametral cuts in a cross-like orientation correspondingly to the relative orientation of said two plate-like inserts and which have an axial extension corresponding to the axial extension of the at least two plate-like inserts and which cuts are further open at the front and shell side of the rod, such that the at least two previously coupled plate-like inserts are introduced together into the cuts of the insert holding rod by a translation in the axial direction of the insert holding rod and they can be removably fastened in the limit insertion position wherein cutting edges along at least a portion of the peripheral edge parallel to the front side of the insert holding rod or along at least a portion of one or of each of the peripheral edges of the inserts protrude for the predetermined amount from said front side and/or from said lateral shell of the insert holding rod respectively . At least one of said plate-like inserts is provided with a rear projection wherein a hole is transversally drilled, and there being further provided a corresponding transversal hole on said insert holding rod, while a screw penetrate through the two holes guaranteeing said inserts to be clamped and centered within the suitable seats in the insert holding rod, when said inserts are in the working position.

Plate-like inserts are provided with indentations and recesses for the mutual snap fit, which are open one towards the other one and have such a length and depth that, with plate-like inserts in the snap fit condition, the cutting edges of each of them take the relative working position corresponding to the one they have in the condition mounted on the rod. The insert provided with the hole for the clamping screw has a groove from said hole and extending towards the end of the insert whose peripheral edge forms the cutting edges and which groove has such a length and width that the other plate-like insert or inserts can be transversally introduced therein.

Such further plate-like insert or inserts have in turn a recess such that, when are transversally introduced into the first plate-like insert through the combination of the hole and the groove coming out therefrom, the further plate-like insert or inserts can be snap fitted in said first plate-like insert and can be brought in the final position by translating them towards the peripheral edges forming the cutting edges or in the axial direction of the rod, by means of which the groove of the first insert provided with the hole and the recess of the further insert or inserts mutually penetrate each other.

The provision of a groove coming out from the hole for the passage of the clamping screw and for centering said inserts allows the hole to be used for introducing the second insert on the first insert at the mutual recesses such to obtain the mutual snap fit of the inserts in a transverse arrangement one with respect to the other . Therefore the two inserts are snap fitted not by sliding the inserts one upon the other at the mutual recesses but it occurs by introducing an insert in the hole for the passage of the clamping screw provided on the second insert by a movement in the axial direction of the hole and then by joining said inserts by means of the relevant recesses by a movement in the radial direction of the hole .

This leads inserts intended to be introduced into the insert holding rod to have a smaller dimension, in particular in the length direction, that is the extension in the axial direction of the rod, and consequently it allows seats removably fastening said inserts to have a smaller depth. This leads to a greater strength, that is a less weakening, of the rod at the end where seats of the inserts are provided and so to a greater strength of the tool even if provided with rods having smaller diameters .

Therefore one of the advantages of the present invention with respect to prior art is the possibility of reducing the depth of the seats in the insert holding rod by using a hole with a groove coming out from said hole for transversally introducing a first insert on a second insert said characteristic not reducing the strength of the rod and the inserts. Morevoer the use of two inserts that are transversally introduced one on the other in combination with a hole and a screw clamping said inserts on the rod allows forces to be released, upon the use of the surface machining means , mainly on the intersecting area of the inserts and not on the clamping screw and consequently it allows the screw and the hole to be smaller, such characteristics helping in increasing the tool strength.

Advantageously the cutting edges of each plate- like insert are formed of at least portions of the peripheral edge of each plate-like insert, which peripheral edge is oriented in a diametral direction of the insert holding rod and which cutting edges are diametrically opposite each other with respect to a central axis oriented parallely to or coinciding with the axis of rotation of the insert holding rod with the inserts mounted therein.

If necessary the cutting edges extend only or even along partial portions of the peripheral edges which are diametrically opposite each other and parallel to or substantially parallel to the axis of the insert holding rod.

According to a preferred embodiment each one of the two diametrically opposite cutting edges of each insert is formed of a portion of the insert peripheral edge which is transverse with respect to the axis of the insert holding rod and of an end portion of the corresponding peripheral edge which is substantially parallel to the axis of the insert holding rod, said two cutting edges being connected each other without interruption by means of the rounded or bevelled corner area provided therebetween.

Said further insert or said further inserts at the side opposite to the one where cutting edges are provided have a projection allowing said groove in the clamping hole of the first insert to be closed, such that when said further insert or said further inserts are engaged each other and with the first insert, said projection completes the edge delimiting the hole and thus said hole has a substantially circular shape, such that the screw can clamp all the previously coupled plate-like elements, in the working position.

It has to be noted that the characteristics of the invention provide the screw to act for retaining inserts on the milling cutter and for clamping them in place by generating mutual abutment conditions among inserts, notches, the hole and the screw. The particular arrangement of the hole and of the recesses mutually engaging inserts as well as of the screw and of the hole thereof in the rear projection of one of the inserts guarantees , with the screw in the mounted condition, a perfect form fit of said parts preventing them from moving, but forces acting on inserts being substantially released on the mutual contacting surfaces of inserts and of the rod of the cutting miller.

According to an improvement the screw (in figures being shown as completely threaded) can be threaded only for an end portion engaging the threaded hole of one of the two portions of the milling cutter divided by the notch housing the perforated insert, while the remaining portion of the screw is cylindrical and it is ground as regards the dimension with respect to the hole in the rear projection of the plate and if necessary the hole in the rod portion delimiting the notch housing said insert on the side of the screw head such to obtain a very high precision form fit of said cylindrical portion of the screw into the corresponding holes of the rear projection of the insert and in the wall delimiting the notch housing said insert.

Further improvements of the invention are object of subclaims .

Characteristics of the invention and advantages deriving therefrom will be more clear from the following description of an not-limitative embodiment shown in annexed drawings wherein:

Fig.l is an exploded perspective view of an embodiment of the tool according to the invention, wherein said tool has four inserts in a cross-like arrangement and which are made as one-piece on two crossed plates.

Fig.2 is a view like fig. 1 showing the plate-like elements upon which inserts are provided snap fitted one into the other in the final position they will have in the mounting condition on the insert holding rod.

Fig.3 is a view taken in the axial direction of the rod from the end thereof holding the plate-like elements with inserts .

Fig.4 is a side elevation view of the insert holding rod showing the two plate-like elements in the mounted condition according to a view direction perpendicular to the screw axis .

Fig.5 is a sectional view of the insert holding rod of fig.4 taken along a diametral cutting plane passing through the axis of the clamping screw and coincident with the median plane parallel to the two largest surfaces of the second plate-like element.

Fig. 6 is a view like figure 5 taken along a diametrial cutting plane perpendicular to the one of figure 5.

Annexed figures show a particular preferred embodiment of the invention providing four cutting edges arranged in pairs on one of the two plate-like inserts respectively. Such embodiment is not limitative and it can be modified by the person skilled in the art by modifying in a clear and obvious way the shown embodiment such that for example there are provided six cutting edges arranged in pairs on one of three inserts respectively which will be arranged angularly staggered, that is in a cross-like arrangement with an angle obviously less than 90°, the latter being provided in the shown embodiment.

In this particular embodiment shown in figure 1 , the tool is composed of an insert holding rod 1 , of inserts composed each of a plate-like element 2 and 3, and upon each of them a pair of cutting edges 201 and 301 is formed, and of a clamping screw 4. A first insert 2 has a rear projection 102 wherein a clamping hole 202 is drilled, from which a groove 302 comes out. The groove 302 is aligned with the central axis of the plate-like insert which is parallel to the axis of the rod 1 in the mounting condition. The groove 302 is provided at the hole side faced towards the plate-like insert end shaped in such a way to form two cutting edges 402 and it leads into the hole 202, while it ends at a predetermined distance from the plate-like element edge forming the two cutting edges 402. The groove 302 has such a width that it can transversally receive a second plate-like insert 3, that is the width of said groove 302 is equal to or slightly larger than the thickness of said second plate-like insert 3.

The side of said second plate-like insert 3 faced towards the edge of the first plate-like insert forming cutting edges 401, in turn forms two cutting edges 301 which are diametrically opposite each other like the two cutting edges 402 on the first plate-like insert 2. Between the two cutting edges 103 there is provided a recess 203 whose width is equal to or slightly greater than the thickness of the first insert 2. Said recess 203 is centered with respect to the central axis of the second insert oriented parallely to the axis of the insert holding rod 1, when it is mounted thereon.

The diameter of the hole 202 and the depth of the groove 302 are greater than the overall extension of the second insert 3 in the axial direction of the groove 302. Moreover the depth of the groove 302 and the depth of the recess 203 of the second plate-like insert 3 have such a dimension that, after the introduction into the hole 202, the groove 302 and the recess 203 of the first insert and of the second insert respectively are aligned each other and said second insert 3 is introduced into the insert 2 by a movement in a direction parallel to the axis of the rod (in the mounted condition thereon) or towards the side with the cutting edges . In this case the two inserts penetrate each other by means of the groove 302 and the recess 203 and in the final mutual engaging position, cutting edges 402 and 103 of the plate-like inserts are arranged in the proper relative position one with respect to the other.

The insert holding rod 1 at the working end has two cuts or notches 401 and 301 and said cuts lay on planes perpendicular each other intersecting at the central axis of rotation of said insert holding rod 1. In the axial direction of the rod 1, the first and second inserts 2, 3 have different lenghts , the first insert 2 being longer than the second insert 3, such that the corresponding diametral cut 401 or the corresponding diametral notch penetrates for a greater amount axially into the insert holding rod 1, namely it has a greater depth than the diametral cut 301 intended to house the second insert 3.

Therefore as it clear from figures , the insert holding rod 1 is divided into four slices 201 up to an axial depth corresponding to the one of the diametral cut 301 intended to house the second plate-like insert 3, while it is divided in two halves for the rod portion wherein only the diametral cut 401 for the first plate-like insert 2 is provided. Such rear axial projection of the first insert 2 has the hole 202, while in the two rod portions divided by the diametral cut 401 for said first insert 2, in a position axially backward with respect to the bottom side of the cut 301 for the second insert and in a position coinciding with the hole 202 of the first insert 2 in the final mounting condition upon said rod 1 , the insert holding rod 1 has a diametral hole 501. Such diametral hole 501 is threaded for at least one of the two portions provided into one of the two rod portions divided by the diametral cut 401 for the first insert 2. Said partially threaded hole 501 is intended to cooperate with a clamping screw 4 for fastening inserts 2 and 3 when they are in their working position.

It is important to note that the particular arrangement described above allows said two inserts 2 , 3 to be engaged and so to be previously fastened one to the other in the proper relative position of the inserts and so of the cutting edges 402, 103, before mounting them on the insert holding rod 1. Moreover they can be mounted on the insert holding rod 1 by a simple insertion movement in the axial direction of the rod. The proper axial position of the two inserts 2, 3 engaged one with the other, with respect to the insert holding rod 1 is defined by the bottom of the two diametral cuts 401, 301. The screw 4 and the corresponding threaded hole 501 serve merely to clamp in place the two inserts 2, 3 inside the seats 301, 402 in the insert holding rod.

According to an improvement, the second insert 3 in a position opposite to the recess 203, namely at the opposite side has a projection 303 allowing said groove 302 to be closed at the side in communication with the hole 202, such that when the inserts 2, 3 are engaged each other, such as shwon in figure 2, the projection completes the edge delimiting the hole 202 and thus said hole 202 has a substantially circular shape. This allows the clamping screw 4 to efficaciously retain in place both the inserts 2 , 3 which have been previosuly coupled each other, in the working position shown in figures 3, 4 and 5 and in figures 6 and 7, where the tool is shown in sectional views, by possibly exerting also a further fine centering action for said inserts 2, 3 on the insert holding rod 1 if desired.

In the shown embodiment, each plate-like insert 2, 3 has a pair of cutting edges provided along diametrically opposite end portions of the edge of the corresponding insert 2, 3 oriented perpendicularly to the axis of rotation of the rod 1 and each one projecting also about the rounded corner connecting said end portion with at least a partial adjacent portion of the cutting edge along the corresponding peripheral edge of the insert oriented in a direction substantially parallel to the axis of rotation of the rod. In the working position, the cutting edges 201 and 301 of inserts 2 and 3 project for a predetermined amount from the front side 201 and from the side shell 101 of the insert holding rod 1.

As already mentioned above the tool can have also for example three inserts that can be previously engaged each other before being assembled on the rod instead of only two inserts 2, 3 arranged in a cross- like arrangement. Each one of said insert has two cutting edges in a position diametrically opposite with respect to the axis of rotation or with respect to the mutual intersecting axis. In this case, grooves 302 and the ones equivalent to grooves 203 will be shaped such to allow the three plate-like inserts to be mutually engaged each other, such arrangement being a simple geometrical modification of the present shown embodiment.

Claims

1. Tool for chip removal machining, particularly for metals, comprising an insert holding rod (1) a predetermined number of plate or slab-like inserts (2, 3) are removably attachable to the working end thereof, which inserts form or are provided with one or more cutting edges (402, 103) along at least a portion of one or more peripheral edges; said insert holding rod (1) being provided with a seat (301, 401) for removably fastening said inserts (2, 3), which seat (301, 401) is formed in the body of the insert holding rod (1) and, with the insert or inserts (2, 3) mounted into said insert holding rod (1) cutting edges (402, 103) formed or provided on said inserts (2, 3) outwardly project therefrom past the front surface (201) and/or the lateral shell surface (101) of said insert holding rod (1) , there being further provided means (4, 501) for removably fastening and means for centering said inserts (2, 3) into said seat or seats (301, 401), said tool has at least four cutting edges (103, 402) provided in pairs on one insert (2, 3) respectively, cutting edges (103, 402) of each pair being provided at opposite ends of the corresponding insert (2, 3) with reference to a median axis of the insert (2, 3) that is parallel to the axis of the insert holding rod (1) with the insert (2, 3) mounted on said insert holding rod (1) ; said two inserts (2, 3) being provided with means (302, 203) for being mutually snap fitted in a cross- like position and the insert holding rod (1) being provided with diametral cuts or notches (301, 401) in a cross-like orientation correspondingly to the relative orientation of said two inserts (2, 3) and which have an axial extension corresponding to the axial extension of the two inserts (2, 3) and which cuts (301, 401) are open at the front side (21) and shell (101) of the insert holding rod (1) , such that the two previously coupled inserts (2, 3) are put together into cuts (301, 401) of the insert holding rod (1) by a translation in the axial direction of the insert holding rod (1) and they can be removably fastened in the limit insertion position wherein cutting edges (402, 103) at the opposite ends of the two inserts (2, 3) protrude for the predetermined amount from the front side (201) and/or from the side shell (101) of the insert holding rod (1) , characterized in that at least one of said inserts (2) is provided with a rear projection wherein a transversal hole (202) is made, and a corresponding transversal hole (501) being further provided on said insert holding rod (1) , a screw (4) penetrate through said holes (4, 501) guaranteeing said inserts (2, 3) to be clamped and centered within suitable cuts (301, 401) in the insert holding rod (1), when said inserts (2, 3) are in the working position mounted on the insert holding rod (1) . inserts (2, 3) being provided with indentations or recesses (302, 303) for the mutual snap fit, which are open one towards the other and have such a length and depth that, with inserts (2, 3) in the snap fit condition, cutting edges (402, 103) of each of them take the relative working position corresponding to the position they have in the condition mounted on the insert holding rod (1) .

2. Tool according to claim 1 characterized in that the insert (2) provided with the hole (202) for the clamping screw (4) has a groove (302) from said hole (202) and extending towards the end of the insert (2) provided which cutting edges (402) and which groove

(302) has such a length and width that the other insert or inserts (3) can be transversally inserted therein and which further insert or inserts (3) have in turn a recess (203) between the two cutting edges (103) such that, when they are transversally inserted into the first insert (2) through said groove (302) , they can be secured in the final position by translating them towards the cutting egdes . 3. Tool according to claim 2, characterized in that the insert or inserts (3) not provided with the clamping hole, at the side opposite to cutting edges (103) are provided with a projection (303) allowing said groove (302) in the clamping hole (202) of the first insert (2) to be obstructed, such that when inserts (2, 3) are engaged one with the other, the edge delimiting the hole (202) is completed by the projection (303) and so said hole (202) has a substantially circular shape, such that the screw (4) can clamp all the previously coupled inserts (2,

3) in the working position.

4. Tool according to one or more of the preceding claims , characterized in that the diameter of the hole (202) within the first insert (2) and the depth of the groove (302) towards said diameter are greater than the overall extension of the second or further inserts (3) , parallel to said diameter and to said depth of the groove (302) , such that the second or further inserts

(3) are placed in a position wherein the recess (203) provided therein is aligned with the groove (302) of the first insert (2) , they being inserted within the opening of the first insert (2) composed of the hole (202) and groove (302) assembly, while the second insert (3) or further inserts are engaged with the first insert by a relative movement towards the axis parallel to the depth of the groove (302) and/or of the recess (203) .

5. Tool according to one or more of the preceding claims, characterized in that the at least two inserts (2, 3) in the working position are arranged according to planes intersecting at the axis of rotation of said insert holding rod (1) .

6. Tool according to one or more of the preceding claims, characterized in that the at least two inserts in the working position are arranged according to planes intersecting not at the axis of rotation of said insert holding rod (1), i.e. in a position eccentric with respect to said axis of rotation of the insert holding rod (1) .

7. Tool according to one or more of the preceding claims , characterized in that it is composed of an insert holding rod (1), with two cuts or notches (301, 401) being made at the working end thereof, which cuts lie on perpendicular planes intersecting at the axis of rotation of said insert holding rod (1) , and of two plate-like inserts (2, 3) provided at least at a side transversal to the axis of rotation of the insert holding rod (1) with a pair of diametrically opposite cutting edges (402, 103) ; one of such two inserts (2) being provided with a rear extension wherein a clamping hole (202) is made; and said hole (202) being provided with a groove (302) projecting towards the cutting edges (402) having such a length and width that the second insert (3) can be inserted therein; and said second insert (3) being provided with a recess (203) in a median position between two diametrically opposite cutting edges (103) which recess is such that, once said second insert (3) is inserted within the first insert (2) by moving it in a direction parallel to the axis of the hole (202) and transversal to the depth extension of the recess (203) , it is brought with said recess (203) in a position aligned with the groove (302) into said first insert (2) , and it is snap fitted within said insert (2) by translating it towards cutting edges (402, 103) or the axis of the insert holding rod (1), such that said two inserts (2, 3) once coupled together are inserted into cuts (301, 401) of the insert holding rod (1) by a translation in the axial direction of the insert holding rod (1) , and said second insert (3) being provided with a projection (303) opposite to the recess (203) allowing said groove (302) in the clamping hole (202) of the first insert (2) to be obstructed, such that when inserts (2, 3) are engaged one with the other, the edge delimiting the hole (202) is completed by the projection (303) and so said hole (202) has a substantially circular shape, such that the clamping screw (4) can clamp all inserts (2, 3) in the working position, and cutting edges (402, 103) of inserts (2, 3) protrude for the predetermined extent from the front side (201) and from the side shell (101) of the insert holding rod (1) .

8. Tool according to one or more of the preceding claims, characterized in that the first insert (2) has a length in the axial direction of the insert holding rod (1) that is greater than the length of the second insert (3) or further inserts, while in the condition with the first insert (2) engaged with the second insert (3) or with further inserts, said first insert (2) rearwardly protrudes in the axial direction past said second insert (3) or further inserts, the hole (202) being provided in said projecting portion of said first insert (2) and while diametral cuts (301, 401) within the insert holding rod (1) have an extension in the axial direction of the insert holding rod (1) corresponding to the extension of the corresponding insert (2, 3) , the cut (401) for the first insert (2) being longer in the axial direction than other cuts (301) , and within the portion of the insert holding rod (1) corresponding to said cut portion (401) for the first insert (2) projecting past cuts (301) for the second and/or further inserts (3) there being provided a diametral threaded hole (501) coinciding with the hole (202) within said first insert (2) and for a clamping screw (4) .

9. Tool according to one or more of the preceding claims, characterized in that said cutting edges (103, 402) are particularly provided along one or more peripheral edges of plate-like inserts (2, 3) and they extend along peripheral edges of inserts (2, 3) projecting past the front side of the insert holding rod and/or past the peripheral shell surface of said insert holding rod and in case also about the rounded corner region connecting said two edges .

10. Insert for milling tools, comprising at least an edge along at least a portion of which edge a cutting edge (402) is provided, said insert being provided in combination with at least a further insert (3) comprising also an edge along at least a portion of which edge a cutting edge (103) is provided, said two inserts being provided with means for being mutually engaged in the proper relative working position of corresponding cutting edges (402, 103) in a position withdrawn from a seat housing them, at least one of said inserts (2) being provided with a rear projection wherein a transversal hole (202) is made, while inserts (2, 3) are provided with indentations or recesses (302, 303) for the mutual snap fit, which are open one towards the other and have such a length and depth that, with inserts (2, 3) in the snap fit condition, cutting edges (402, 103) of each of them take the relative working position corresponding to the position in the condition mounted within a mounting seat.

11. Insert according to claim 10, characterized in that the insert (2) provided with the hole (202) for the clamping screw (4) has a groove (302) from said hole (202) and extending towards the end of the insert (2) provided with cutting edges (402) and which groove (302) has such a length and width that the other insert or inserts (3) can be transversally inserted therein and which further insert or inserts (3) have in turn a recess (203) between the two cutting edges (103) such that, when they are transversally inserted into the first insert (2) through said groove (302) , they can be secured in the final position by translating them towards the cutting egdes .

12. Insert according to claim 11, characterized in that the insert or inserts (3) not provided with the clamping hole, at the side opposite to cutting edges

(103) are provided with a projection (303) allowing said groove (302) in the clamping hole (202) of the first insert (2) to be obstructed, such that when inserts (2, 3) are engaged one with the other, the edge delimiting the hole (202) is completed by the projection (303) and so said hole (202) has a substantially circular shape.

13. Insert according to claim 11, characterized in that the diameter of the hole (202) within the first insert (2) and the depth of the groove (302) towards said diameter are greater than the overall extension of the second or further inserts (3) , parallel to said diameter and to said depth of the groove (302) , such that the second or further inserts (3) are placed in a position wherein the recess (203) provided therein is aligned with the groove (302) of the first insert (2) , they being inserted within the opening of the first insert (2) composed of the hole (202) and groove (302) assembly, while the second insert (3) or further inserts are engaged with the first insert by a relative movement towards the axis parallel to the depth of the groove (302) and/or of the recess (203) .

14. Insert according to one or more claims 10 to 13, characterized in that it has one or more of the characteristcs provided in combination with a tool according to claims 1 to 9.