WO2026008739A1 - Machining insert, insert holder, and machining assembly - Google Patents

Abstract

The invention relates to a machining insert intended to be mounted on an insert holder having a bottom (26), wherein the machining insert comprises a central portion (1) extending along a longitudinal axis (X) and having a front face (3) arranged so as to be able to bear against the bottom (26) of the insert holder, and also comprises a hole (7) that passes through the entire thickness of the central portion (1), perpendicularly to the longitudinal axis (X). According to the invention, the insert comprises a single wing (8) that extends along the longitudinal axis (X) from a first side of the central portion (1) and is intended to provide a machining function. In addition, the insert comprises at least one first contact surface which is intended to form, with a second contact surface provided on the insert holder, a region of tangential contact, perpendicular to the longitudinal axis (X), when the insert abuts against the insert holder along the longitudinal axis (X). The invention also relates to an insert holder and to a machining assembly.

Description

MACHINING INSERTS, INSERTS HOLDER AND MACHINING ASSEMBLY

technical field

The invention relates to a machining insert, an insert holder and a machining assembly.

State of the art

Swiss patent no. CH 686 935 relates to a lathe comprising a support on which is mounted a cutting insert consisting of a central part and two wings symmetrical by rotation of 180 degrees, each having a cutting edge for machining a workpiece. The support has two recesses, one to receive one of the wings and the other to receive the central part of the insert, which is held in place by a single screw on the support. The main drawback of such an assembly is that the free wing of the insert is significantly cantilevered from the support.

The international application published under number WO 01/00360 relates to a cutting tool comprising a grooved insert holder on which is mounted, by means of two screws, an insert having a thick central part ribbed to be able to cooperate with the grooves of the insert holder, two thin wings set back from the ribs and two cutting edges.

The international application published under number WO 2005/007329 relates to a cutting tool having a grooved insert holder on which is mounted an insert having a thick, ribbed central portion to cooperate with the grooves in the insert holder, two thin wings set back from the ribs, and two cutting edges. The insert is held on the insert holder by means of a single screw passing through corresponding holes made in the insert and the insert holder, and around which flat surfaces have been created by interrupting the ribs and grooves. These documents all describe machining inserts that include two cutting edges. However, such inserts have a significant length. They are therefore not suitable for tool holder systems that require a small overall length.

The present invention aims to remedy these drawbacks by proposing an insert and an insert holder that can be used in a tool holder system offering a reduced length footprint with improved stability of the insert clamping on the insert holder.

Disclosure of the invention

To this end, the invention relates to a machining insert intended to be mounted on an insert holder comprising a base, said insert having a central part extending along a longitudinal axis (X) and comprising a front face arranged to be able to come to rest against the base of the insert holder, and a hole passing through the central part in its entire thickness, perpendicular to the longitudinal axis (X).

According to the invention, the insert comprises a single wing extending along the longitudinal axis (X) from a first side of the central portion and intended to perform a machining function. The insert further comprises at least one first contact surface intended to form, with a second contact surface provided on the insert holder, a tangential contact zone, perpendicular to the longitudinal axis (X), when the insert is abutted along the longitudinal axis (X) against the insert holder.

The invention also relates to a plate holder designed to cooperate with the plate as defined above, said plate holder extending along an axis (Y) designed to be parallel to the longitudinal axis (X) of the plate and having:

- a front face, a top face and a back face,

- a recess opening towards the front face and having:

• a background forming a face parallel to the (Y) axis, • a longitudinal wall parallel to the (Y) axis,

• a transverse wall extending from the longitudinal wall of the recess to the upper face of the plate holder,

- a hole extending from the bottom of the recess to the rear face of the plate holder, perpendicular to the (Y) axis.

According to the invention, the transverse wall of the recess extends substantially perpendicularly to the axis (Y). In addition, said insert holder comprises at least a second contact surface intended to form, with a first contact surface provided on the insert, a tangential contact zone, perpendicular to the longitudinal axis (Y), when the insert is abutted along the longitudinal axis (Y) against the insert holder.

Thus, the insert according to the invention has only one cutting edge and is neither symmetrical nor reversible. Its manufacture is therefore faster, particularly because it only has one edge to grind. Furthermore, this insert can be mounted using a single fixing screw.

Furthermore, the insert according to the invention, with a single cutting edge, advantageously has a shorter length compared to prior art inserts. It can therefore be used on tool holder systems requiring a reduced overall length.

Furthermore, the insert with a single cutting edge and its insert holder according to the invention offers improved clamping stability, as a second cutting edge would significantly reduce the clamping surface and, consequently, stability. This results in greater rigidity of the system.

The invention also relates to a machining assembly, that is to say, an insert/insert holder assembly comprising the insert and the insert holder as defined above, said machining insert being mounted against the insert holder along its longitudinal axis, said having at least one first contact surface of the machining insert forming, with said at least one second contact surface of the insert holder, at least one tangential contact area, perpendicular to said longitudinal axis.

Brief description of the drawings

Other features and advantages of the present invention will become apparent from the following detailed description of several embodiments of the invention, given by way of non-limiting examples, and made with reference to the accompanying drawings in which:

- Figure 1 is a perspective front view of a plate according to the invention;

- Figure 2 is a perspective view of a first embodiment of a plate holder according to the invention;

- Figure 3 is a front view of the plate holder of Figure 2, on which a plate has been mounted according to Figure 1, with a circle designating a detail R;

- Figure 4 represents detail R designated in Figure 3;

- Figure 5 is a top cross-sectional view of the insert holder in Figure 3;

- Figure 6 is a perspective view of a second embodiment of a plate holder;

- Figure 7 shows the plate holder of Figure 6 on which a plate according to the invention has been mounted, in front view; - Figure 8 shows the insert holder from Figure 7, in a top cross-sectional view;

- Figure 9 represents an enlargement of part of Figure 8;

- Figures 10 and 11 represent a plate holder according to Figure 2 in front view and left view in section, showing how a plate is mounted on the plate holder;

- Figures 12 and 13 represent a plate holder according to Figure 2, in front view and left view in section, showing another way of mounting a plate on the plate holder; - Figures 14 and 15 represent a plate holder according to Figure 6 in front view and left view in section, showing how a plate is mounted on the plate holder;

- Figures 16 and 17 represent a plate holder according to Figure 6 in front view and left view in section, showing another way of mounting a plate on the plate holder;

- Figure 18 shows the mounting of a plate according to the invention on a plate holder according to the invention;

- Figure 19 represents a variant of the plate holder according to the invention on which two plates according to the invention are mounted; Figure 20 represents a variant of the insert holder according to the invention on which is mounted an insert according to the invention with a quick change system;

- Figure 21 shows the plate holder of Figure 20, in perspective view, and

- Figure 22 represents the insert holder of Figure 20, in perspective view and with the insert holder being assembled.

Methods of embodying the invention

The present invention relates to a plate holder extending along a Y-axis and having:

- a front face 20, an upper face 21 and a rear face 30,

- a recess 22 opening towards the front face 20 and having:

• a base 26 forming a face parallel to the Y axis,

• a longitudinal wall 24 parallel to the Y axis,

• a transverse wall 25 extending substantially perpendicularly to the Y axis, from the longitudinal wall 24 of the recess 22 to the upper face 21 of the plate holder,

- a hole 29 extending from the bottom 26 of the recess 22 to the rear face 30 of the insert holder, perpendicular to the Y-axis, said insert holder being configured to receive a machining insert as defined below abutted along the longitudinal axis Y against the insert holder, said machining insert comprising a central portion 1 extending along a longitudinal axis X, the Y-axis of the insert holder being provided to be parallel to the X-axis of the machining insert, said insert holder having at least one second contact surface configured to form, with a first contact surface provided on said machining plate in stop, at least one tangential contact zone 11, perpendicular to the longitudinal axis Y.

The present invention also relates to a machining insert comprising:

- a central part 1 extending along a longitudinal axis X and comprising a front face 3,

- a hole 7 passing through the central part 1 in its entire thickness, perpendicular to the longitudinal axis X,

- a single wing 8 extending along the longitudinal axis X from a first side of the central part 1 and intended to perform a machining function, said machining insert being specifically designed to be mounted on an insert holder as defined above in abutment along the longitudinal axis X against said insert holder, said machining insert having at least a first contact surface configured to form, with a second contact surface provided on the insert holder, at least one tangential contact zone 11, perpendicular to the longitudinal axis X, and the front face 3 of the machining insert being arranged to bear against a bottom 26 of the insert holder.

The present invention also relates to a machining assembly comprising a tool holder as defined above, on which a machining insert as defined above has been mounted against the longitudinal axis X, said at least a first contact surface of the machining insert forming, with said at least a second contact surface of the tool holder, at least a tangential contact zone 11, perpendicular to the longitudinal axis X.

Plate according to the invention

An example of an embodiment of a plate according to the invention is shown in Figure 1. Such a plate is generally made of tungsten carbide. As can be seen in this figure, the plate has a central part 1 extending along a longitudinal axis X and having a rear face 2 and a front face 3 that are generally parallel.

The front face 3 is preferably provided with ribs 4 parallel to each other and extending along the longitudinal axis X. The lower face of the plate is designated by the number 16 and its upper face by the number 17.

The ribs 4 each have a base 5 and a vertex 6. They preferably have a triangular cross-section and their vertices 6 are preferentially truncated, as can be seen in Figure 1.

In an embodiment not shown, the rib crests have a slight central hollow to ensure contact points at the ends and supports tangent to the flats of the grooves in the insert holder. This allows for more precise support, ensuring better stability.

In the central part 1, preferably in its center, there is a hole 7 which passes through it from the front face 3 to the rear face 2, perpendicular to the X axis. If we disregard this hole 7, the ribs 4 are identical to each other.

The central part 1 is extended, on one side, by a wing 8 intended to perform a machining function. Said wing 8 is without ribs, extends along the longitudinal axis X and has a rear face 9 preferably at the same level as the rear face 2 of the central part 1.

Wing 8 preferably has the same thickness as the central part 1 unless the latter has ribs 4, in which case the flat front face 11 of wing 8 is located at the level of the base of the ribs 4, that is to say at the level of the hollows located between them.

At the top of the free axial longitudinal end of wing 8 is the cutting edge 18 of the plate. According to the invention, the plate comprises a single wing 8.

Advantageously, the second side of the central part 1, opposite longitudinally to the first side, comprises a ribless extension 10. This extension 10 has a length along the X-axis shorter than that of the wing 8 and preferably has the same thickness as the central part 1 unless the latter has ribs 4, in which case the flat front face 12 of the extension 10 is located at the level of the base of the ribs 4.

The rear face 37 of the extension 10 is preferably at the same level as the rear face 2 of the central part 1.

Thus, the rear faces 2, 9 and 37 of the central part 1, of the wing 8 and of the extension 10 can together form a continuous flat surface.

Advantageously, the central part 1 has, at the end of its end 10, on the side opposite longitudinally to its first side, an end surface 19 perpendicular to the longitudinal axis X and which preferably extends over the entire thickness of the central part 1. As will be described in more detail below, said end surface 19 is capable of serving as the first contact surface intended to subsequently form, with a second contact surface provided on the insert holder, a tangential contact zone 11, said zone 11 being perpendicular to the axis X, when the insert is abutted along the longitudinal axis X against the insert holder.

According to an advantageous embodiment, inclined planes 13, 14 are provided at the end of the extension 10, on the upper and lower sides of its free end. They are therefore located on each side of the end surface 19. These inclined planes 13, 14 can be obtained by machining the upper and lower corners of the extension 10, removing material and thus reducing the weight of the insert. Only the end surface 19 of the extension 10 then needs to be ground before the insert is used. According to another embodiment of the insert, the ends of the ribs located on the wing side 8 are connected by a nerve 15 which extends perpendicularly to the X axis, forming bridges between two adjacent ribs. This nerve 15 is also capable of serving as a first contact surface intended to subsequently form, with a second contact surface provided on the insert holder, a tangential contact zone 11, perpendicular to the X axis, when the insert is abutted along the longitudinal X axis against the insert holder.

It is quite clear that the two embodiments (end surface 19/ nerve 15) can be provided together on one and the same plate, said plate being able to be used indifferently with either embodiment of the plate holder, or that they can be provided separately, one type of plate then being used with the corresponding embodiment of the plate holder, as will be detailed below.

First embodiment of a plate holder according to the invention

The plate according to the invention as described above is intended to be mounted on a plate holder according to a first embodiment such as that visible in figure 2.

This insert holder has an elongated shape along a Y-axis designed to be, after assembly, parallel to the X-axis of the insert. It has a front face 20, a top face 21, and a substantially parallelepiped-shaped recess 22 opening towards the front face 20 of the insert holder and possibly towards the top face 21 of the insert holder.

The recess 22 has a bottom 26 which forms a face parallel to the Y axis and which is preferably provided with grooves 23 extending parallel to the X axis from the front face 20 of the plate holder.

The recess 22 also has a longitudinal wall 24 parallel to the Y-axis and a transverse wall 25 substantially perpendicular to the Y-axis and extending from the longitudinal wall 24 to the upper face 21 of the insert holder. Unlike the prior art, the transverse wall 25 does not need to include a housing to receive the cutting edge that is not in use.

The only three walls of the recess, namely the bottom 26, the longitudinal wall 24 and the transverse wall 25, are preferably perpendicular to each other.

The possible grooves 23 may advantageously not extend to the transverse wall 25. There then remains a flat surface 27 between the transverse wall 25 and the end of the adjacent grooves 23.

Preferably, the cross-section of the grooves 23 is substantially triangular.

The parts located between the grooves preferably have truncated tops, so as to form facets 28 parallel to the bottom 26 of the recess 22.

A hole 29, preferably tapped, extends from the bottom 26 of the recess 22 to the rear face 30 of the insert holder, perpendicular to the Y axis. This hole 29 is preferably located in the center of the recess 22. If we disregard this hole 29, the grooves 23 are identical to each other.

The transverse wall 25 can serve as a second contact surface intended to form, with a first surface of the insert, a tangential contact zone 11, perpendicular to the longitudinal axis Y, when the insert is abutted against the insert holder along the longitudinal axis Y. The transverse wall 25 is preferably slightly convex inwards towards the recess 22, as can be seen in particular in Figure 2. This inwards convexity constitutes said second contact surface and allows the creation of a plane of tangency with the end surface 19 of the insert in Figure 1, which constitutes the first contact surface. Plate assembly according to the invention and plate holder of the first embodiment according to the invention

Figures 3 to 5 show the plate holder of figure 2 on which the plate of figure 1 has been mounted. The dimensions of the recess 22 are approximately equal to those of the central part 1 and the extension 10 which it must house.

These figures show the preferred versions featuring ribs and grooves. These ribs 4 and grooves 23 have complementary shapes allowing them to interlock. The length of the grooves 23 is at least equal to that of the ribs 4. The assembly of the insert in the insert holder is facilitated, where applicable, by chamfers on the longitudinal ends of the ribs 4 and/or truncations at their apexes 6.

The insert is held in the recess 22 by means of a single screw 31, visible in Figure 5, preferably inserted into the hole 7 of the insert from its rear face 2, and then screwed into the hole 29 of the insert holder. Preferably, the screw 31 has a conical head and the hole 7 is flared to receive this conical head.

In this variant, the transverse wall 25 of the recess 22 acts as a stop or second contact surface for the end surface 19 of the insert which includes the first contact surface, in order to form the tangential contact zone 11, perpendicular to the longitudinal axis X. As the transverse wall 25 is preferably convex, the contact between the insert and the insert holder is then tangential.

Alternatively, the transverse wall 25 could be flat and the end surface 19 of the extension 10 convex.

It is also possible to consider that both the transverse wall 25 and the end surface 19 of the extension 10 are convex. In this case, the contact would occur between two convexities. Advantageously, as can be seen by returning to Figure 2, a recess 32 has been machined near the front face 20 of the insert holder, between the longitudinal wall 24 of the recess 22 and the upper face 21, until it reaches at least the same depth as the grooves 23. The recess 32 extends perpendicularly to the Y axis, preferably from the deepest part of the groove 23 closest to the upper face 21 to the deepest part of the groove 23 closest to the longitudinal wall 24.

Thanks to the recess 32, this insert holder can be used with an insert according to the invention comprising a nerve 15, because the latter can then be housed in the recess 32, the end surface 19 of the extension 10 of the insert coming against the transverse wall 25 of the recess 22 to form the tangential contact zone 11.

Second embodiment of a plate holder according to the invention

This insert holder is visible in Figure 6. It has the same shape as the insert holder of insert 2, with at least one exception: the material bordering the grooves 23 has been machined at an angle on the side opposite the transverse wall 25, preferably deeper than the grooves 23, so as to create an inclined face 34 extending only slightly, longitudinally, from the front face 20 of the insert holder towards the front wall 25 of the recess 22 and, more, transversely, from the longitudinal wall 24 of the recess 22 to the upper face 21 of the insert holder, preferably being perpendicular to the Y axis. This inclined face 34 is intended to form the second contact surface, the first contact surface being then provided on the ridge 15 of an insert of Figure 1.

The free upper end of the inclined face 34 has a toothed shape because of the ribs 23 and it may optionally include a chamfer 35.

Plate assembly according to the invention and plate holder of the second embodiment according to the invention Figures 7 to 9 show the plate holder of figure 6 on which the plate of figure 1 has been mounted.

The difference, compared to the set of figures 3 to 5, is that the plate no longer comes to rest against the transverse wall 25 of the recess 22.

Indeed, it is here the nerve 15, and more precisely the bridges it forms between the grooves 23, which comes/come at an angle in tangential or quasi-tangential contact against the teeth of the inclined face 34 of the insert holder, as can be seen better on the enlargement of figure 9. Thus, the first contact surface is provided on the nerve 15 of the insert and the second contact surface is constituted by the inclined face 34 of the insert holder in order to form the tangential contact zone 11, perpendicular to the longitudinal axis Y, represented schematically on figures 7, 14 and 16, when the insert is in butt along the longitudinal axis Y against the insert holder.

It follows that in this variant, a gap is formed between the end surface 19 of the extension 10 and the transverse wall 25 of the recess 22, a gap which appears in figures 7 and 18. The end surface 19 of the extension 10 could then remain raw (unrectified).

Positioning of the ribs relative to the grooves

In the above, the cooperation of the ribs 4 with the grooves 23 has been referred to collectively under the general term “interlocking”.

Only the longitudinal positioning of the insert in the insert holder has been described and two possibilities have been considered: a positioning by means of a rear tangential stop, namely, against the transverse wall 25 of the recess 22 of the insert holder (Figs. 3 to 5) and a positioning with a front tangential stop, that is to say against the inclined face 34, near the front face 20 of the insert holder (Figs. 7 to 9). Regarding the transverse positioning of the insert in the insert holder, two possibilities can also be considered: an assembly with a "bottom of the teeth" type clamping and an assembly with a "staggered teeth" type clamping, which will be described below.

Assembly with "bottom-of-gear" type clamping

Figures 10 and 11 represent the assembly of figures 3 to 5, consisting of a plate of figure 1 mounted on the plate holder of figure 2. As can be seen in figure 11, the contact (visualized by the thick lines in figure 11) between the ribs 4 and the grooves 23 is classic, complete, as in the aforementioned international application WO 2005/007329, that is to say that all the faces of the ribs 4 of the plate are pressed against all the faces of the grooves 23 of the plate holder by the screw 31.

The same applies to figures 14 and 15 where the set of figures 7 to 9 is represented, consisting of a plate of figure 1 mounted on the plate holder of figure 6 with a classic assembly of the type “bottom of teeth”.

Assembly with "offset gear" type clamping

Figures 12 and 13 show the assembly of figures 3 to 5, consisting of a plate according to figure 1 mounted on the plate holder of figure 2. As can be seen in figure 12, the contact (see thick lines) between the ribs 4 and the grooves 23 is partial, incomplete, as in the aforementioned international application WO 01/00360, only certain faces of the ribs 23 of the plate being pressed against certain faces of the grooves 4 of the plate holder by the screw 31.

More specifically, contact is only made between the faces of the ribs 4 located on the side of the upper face 17 of the insert and the faces of the grooves 23 located on the side of the upper face 21 of the insert holder. Although the ribs 4 and the grooves 23 have complementary shapes, the interlocking is designed not to be complete. This is clearly visible when comparing Figure 11 to Figure 13.

This assumes that the ribs 4 do not fully penetrate the grooves.

23 and therefore the plate is inserted slightly less deeply into the recess and, consequently, its rear face 2 is not totally level with the front face 33 of the plate holder, but the difference in level is almost imperceptible to the naked eye.

This result is obtained by ensuring that the distances between the lower face 16 (fig. 13) of the plate and the midpoints of the ribs 4 are slightly greater than the respective distances separating the longitudinal wall

24 of the recess 22 and the centers of the grooves 23 of the insert holder.

In figure 12, the designation D1 means that the tapping of the hole 29 of the insert holder is off-center so that the insert is pulled backwards and comes to rest against the transverse wall 25.

The mention D2 means that the teeth are offset towards face 21 of the insert holder so that all the rib 4/groove 23 supports are on the same side, respectively towards faces 17 and 21. But the lower face 16 of the insert is indeed in butt against the longitudinal wall 24 of the insert holder (see thick lines).

Similarly, figures 16 and 17 represent the set of figures 7 to 9, consisting of a plate according to figure 1 mounted on the plate holder of figure 6 with an assembly of the type "offset tooth bottom".

Comparing Figure 15 with Figure 17, we also see that, in Figure 17, only the upper faces of the ribs 4 come into contact with the upper faces of the grooves 23 of the insert holder.

Use - Assembly The insert/insert holder assemblies according to the invention can be used as such, as primed tool holders, the insert holders then acting as tool holders carrying the inserts, as can be seen in figures 18 and 19. In figure 18, a second optional screw 36 is shown for optional tightening by the rear face 30 of the insert holder.

Figure 19 shows a double tool holder arranged to receive two inserts. Each tool holder is like those described previously and is connected to the other by a single support. The insert/insert assemblies according to the invention can also be mounted on a tool holder as shown in Figures 20 to 22, which depict a quick-change mounting system known as "Switch-Line".

The invention therefore also extends to tool holders equipped with machining assemblies such as those just described, as well as to the use of these machining assemblies as primed tool holders.

Claims

Demands 1. Machining insert intended to be mounted on an insert holder comprising a base (26), said machining insert comprising: - a central part (1) extending along a longitudinal axis (X) and comprising a front face (3) arranged to be able to bear against the bottom (26) of the plate holder, and - a hole (7) passing through the central part (1) in its entire thickness, perpendicular to the longitudinal axis (X), characterized in that said machining insert comprises a single wing (8) extending along the longitudinal axis (X) from a first side of the central part (1) and intended to perform a machining function, and in that said machining insert comprises at least a first contact surface intended to form, with a second contact surface provided on the insert holder, a tangential contact zone (11), perpendicular to the longitudinal axis (X), when the machining insert is abutted along the longitudinal axis (X) against the insert holder. 2. Machining insert according to claim 1, characterized in that the central part (1) has, on the side opposite longitudinally to its first side, an end surface (19) perpendicular to the longitudinal axis (X) and preferably extending over the entire thickness of the central part (1). 3. Machining insert according to claim 2, characterized in that inclined planes (13,14) are provided on each side of the end surface (19). 4. Machining insert according to any one of the preceding claims, characterized in that the front face (3) is perpendicular to the hole (7) and provided with ribs (4) parallel to each other and extending along the longitudinal axis (X). 5. Machining plate according to claim 4, characterized in that the longitudinal ends of the ribs (4) located on the wing side (8) are connected by a nerve (15) extending perpendicularly to both the longitudinal axis (X) and the hole (7). 6. Machining insert according to any one of claims 2 to 5, characterized in that said first contact surface is provided on the end surface (19). 7. Machining insert according to claim 5, characterized in that said first contact surface is provided on the nerve (15). 8. Insert holder intended to cooperate with an insert according to any one of claims 1 to 7, said insert holder extending along an axis (Y) intended to be parallel to the axis (X) of the machining insert and having: - a front face (20), a top face (21) and a rear face (30), - a recess (22) opening towards the front face (20) and having: • a base (26) forming a face parallel to the axis (Y), • a longitudinal wall (24) parallel to the axis (Y), • a transverse wall (25) extending from the longitudinal wall (24) of the recess (22) to the upper face (21) of the plate holder, - a hole (29) extending from the bottom (26) of the recess (22) to the rear face (30) of the insert holder, perpendicular to the axis (Y), characterized in that the transverse wall (25) of the recess (22) extends substantially perpendicular to the axis (Y) and in that said insert holder has at least a second contact surface intended to form, with a first contact surface provided on the machining insert, a tangential contact zone (11), perpendicular to the longitudinal axis (Y), when the machining insert is abutted along the longitudinal axis (Y) against the insert holder. 9. Insert holder according to claim 8, characterized in that the transverse wall (25) has a bulge towards the inside of the recess (22), said bulge constituting said second contact surface. 10. Insert holder according to claim 8 or 9, characterized in that the base (26) is provided with grooves (23) extending parallel to the axis (Y) and intended to cooperate with the ribs (4) of a machining insert according to claim 4 or according to any one of claims 5 to 7 dependent on claim 4. 11. Insert holder according to claim 10, further comprising a recess (32) located near the front face (20) of the insert holder, between the longitudinal wall (24) of the recess (22) and the upper face (21), having at least the same depth as the grooves (23). 12. Insert holder according to claim 10, further comprising an inclined face (34) extending longitudinally from the front face (20) of the insert holder to the transverse wall (25) of the recess (22) and transversely from the longitudinal wall (24) of the recess (22) to the upper face (21) of the insert holder, this inclined face (34) being provided to form said second contact surface, the first contact surface being provided on the ridge (15) of a machining insert according to one of claims 5 and 7. 13. Machining assembly comprising a tool holder according to any one of claims 8 to 12, on which a machining insert according to any one of claims 1 to 7 is mounted as a butt along the longitudinal axis (X) against said tool holder, said at least a first contact surface of the machining insert forming, with said at least a second contact surface of the tool holder, at least one tangential contact zone (11), perpendicular to the longitudinal axis (X). 14. Machining assembly comprising an insert holder according to any one of claims 8 to 11, on which a machining insert is mounted according one of claims 2 and 3, the first contact surface being provided on the end surface (19) of the machining insert and being abutted against the second contact surface provided on the transverse wall (25) of the insert holder. 15. Machining assembly comprising an insert holder according to claim 11 on which a machining insert has been mounted according to one of claims 2 and 3 and claim 5, the first contact surface being provided on the end surface (19) of the machining insert and being abutted against the second contact surface provided on the transverse wall (25) of the insert holder and the nerve (15) being housed in the recess (32). 16. Machining assembly comprising an insert holder according to claim 12 on which a machining insert according to claim 5 has been mounted, the first contact surface being provided on the nerve (15) of the insert and being in abutment against the second contact surface constituted by the inclined face (34) of the insert holder. 17. Machining assembly according to any one of claims 13 to 16, wherein the front face (3) of the machining insert is perpendicular to the hole (7) and provided with ribs (4) parallel to each other and extending along the longitudinal axis (X), and the bottom (26) of the insert holder is provided with grooves (23) extending parallel to the axis (Y) and provided to cooperate with the ribs (4) of said machining insert, and wherein the machining insert has been assembled on the insert holder with a "root of teeth" type clamping, the entirety of the faces of the ribs (4) of the machining insert being pressed against the entirety of the faces of the grooves (23) of the insert holder by a screw (31). 18. Machining assembly according to any one of claims 13 to 16, in the front face (3) of the machining insert is perpendicular to the hole (7) and provided with ribs (4) parallel to each other and extending along the longitudinal axis (X), and the bottom (26) of the insert holder is provided with grooves (23) extending parallel to the axis (Y) and intended to cooperate with the ribs (4) of said machining insert, and in which the machining insert has been assembled on the insert holder with a clamping of the "offset teeth" type, only the upper faces of the ribs (4) being pressed against the only upper faces of the grooves (23) of the insert holder by a screw (31).