Cutting insert and machining tool

Abstract

The present invention relates to a cutting insert (10) for a tool (100) for machining a workpiece. The cutting insert (10) comprises a clamping part (12) with at least one coolant channel (34) configured as a through hole. Furthermore, the cutting insert (10) comprises a cutting head (14) with a main cutting edge (26), a rake face (30) adjacent to the main cutting edge (26) and a chip breaking geometry (32) protruding from or introduced into the rake face (30) and configured to break chips machined by the main cutting edge (26). Furthermore, the cutting insert (10) comprises a cantilever arm (16) connecting the clamping part (12) to the cutting head (14) and having a smaller diameter than the clamping part (12). A portion of the cutting head (14) having a chip breaking geometry (32) at least partially covers the coolant channel (34) when viewed in plan from the front side along the longitudinal axis (38) of the cutting insert (10).

Description

Technical Field

[0001] The present invention relates to a cutting insert for a tool for machining a workpiece. The present invention further relates to a tool provided with such a cutting insert.

Background Art

[0002] The tool according to the present invention may be, for example, a reamer tool. However, the present invention is not limited to such a reamer tool. Further, the tool according to the present invention into which the cutting insert according to the present invention is inserted may be different types of cutting tools, such as a tool bit, a drilling tool, a milling tool, etc. The tool according to the present invention is preferably used in a machine tool such as a CNC processing center.

[0003] The tool according to the present invention has, in addition to the cutting insert, a cutting insert holder for holding the cutting insert. Preferably, the cutting insert is removably fixed in the cutting insert holder so that it can be replaced in case of wear.

[0004] The main purpose of such a tool is to produce the best chip breakage in order to avoid unduly long chips during machining. Good chip breakage characteristics not only increase the service life of the cutting insert used in the tool, but also have a positive effect on the surface quality of the machined workpiece.

[0005] In order to increase the service life and improve the reliability of machining, it is necessary to supply a sufficient amount of coolant / lubricating oil (hereinafter abbreviated as "coolant") to the machining location. Therefore, coolant channels are often integrated into the tool and / or the cutting insert. These are intended to ensure that the most highly loaded areas of the tool receive a sufficient amount of coolant at all times during use.

[0006] Examples of machining tools with integrated coolant channels are disclosed in the following documents: German Patent Publication No. 10 2007 023 167, German Patent Publication No. 10 2010 002 669, German Patent Publication No. 10 2010 021 520, German Patent Publication No. 10 2010 051 377, German Utility Model Publication No. 2004 008 566, European Patent No. 2 146 816, European Patent No. 2 148 757, European Patent No. 2 550 126.

SUMMARY OF THE INVENTION

PROBLEM TO BE SOLVED BY THE INVENTION

[0007] An object of the present invention is to provide a cutting insert for a machining tool and such a tool in which chip breaking characteristics and coolant supply are further improved.

MEANS FOR SOLVING THE PROBLEM

[0008] According to the present invention, this object is achieved by including a cutting insert having the following. A clamping portion having at least one coolant channel configured as a through-hole, A cutting head having at least one cutting member including a main cutting edge, a rake face adjacent to the main cutting edge, and a chip breaking geometry portion configured to protrude from the rake face or be introduced into the rake face and break a chip machined at the main cutting edge, A clamping portion connecting the clamping portion to the cutting head and having a cantilever arm with a diameter smaller than that of the clamping portion, A part of the cutting head having the chip breaking geometry portion at least partially covers the coolant channel in a plan view from the front side along the longitudinal axis of the cutting insert.

[0009] As a result of the chip-breaking geometry provided on at least one cutting member, the chip-breaking characteristics of the cutting insert according to the present invention are significantly improved. Further, by geometrically covering the coolant channel with a part of the cutting head where the chip-breaking geometry is arranged, optimal coolant supply is ensured. In contrast to what is common with conventional cutting inserts, this ensures that the coolant reaches a decisive position for the chip-breaking characteristics of the cutting insert. This is because most of the coolant discharged from the coolant channel consequently impinges directly on the chip-breaking geometry and is not ejected towards the opposite side or laterally of the cutting member of the cutting insert as is common in other cases.

[0010] When the coolant channel is geometrically covered by the chip-breaking geometry as described above, it is observed that the jet of coolant discharged from the coolant channel impinges on a part of the cutting head and is thereby partially redirected by the cutting head as it appears in a plan view from the front face. However, this has been found to significantly improve the chip formation characteristics compared to cutting inserts and cutting tools where the coolant jet sprays completely freely (i.e., without being redirected) across the blade. In any case, as a result of the configuration of the cutting insert according to the present invention, improvement in chip breaking and a higher level of machining reliability can be achieved.

[0011] Therefore, the above object is completely solved.

[0012] Preferably, the cutting insert is configured in a one-piece manner, i.e., composed of one piece, such that the clamping part, the cutting head, and the cantilever arm are integrally connected to each other.

[0013] This increases the mechanical stability of the cutting insert, which is particularly advantageous when the size of the cutting insert is relatively small.

[0014] According to another improvement example, it is preferable that the cantilever arm does not cover the coolant channel in a plan view from the front along the longitudinal axis of the cutting insert.

[0015] This has the advantage that the coolant jet discharged from the coolant channel is discharged from the clamp portion and reaches the cutting head without colliding with the cantilever arm or being deflected by the cantilever arm and without being restricted by the cutting head. Therefore, the coolant jet retains most of its kinetic energy up to the collision position with the chip-breaking geometry portion arranged on the cutting head.

[0016] According to another improvement example, the chip-breaking geometry portion is arranged spaced apart from the main cutting edge, and a first portion of the rake face is provided to extend along the main cutting edge between the chip-breaking geometry portion and the main cutting edge.

[0017] Thereby, a positive cutting angle can be achieved, and thereby the chip-breaking characteristics can be further improved. This is particularly advantageous in reamer tools or other cutting tools where generally very thin chips are generated. Such thin chips would not be broken in a sufficiently reliable manner without the above-mentioned positive cutting angle in combination with the chip-breaking geometry of the present invention. This leads to scratches on the surface of the cutting member, and as a result, scratches on the rake face, which ultimately increases wear and shortens the service life of the cutting insert.

[0018] According to another improvement example, the cutting member further includes an auxiliary cutting edge oriented transversely to the main cutting edge, and a second portion of the rake face extends along the auxiliary cutting edge between the chip-breaking geometry portion and the auxiliary cutting edge.

[0019] The term "transverse direction" in this example refers to the direction of two cutting edges at an angle not equal to 0 degrees. The two cutting edges (the main cutting edge and the auxiliary cutting edge) are preferably oriented at an acute or right angle to each other. However, in principle, they can also be oriented at an obtuse angle to each other.

[0020] The chip-breaking geometry part of the previously described improvement example is completely surrounded by the rake face in both the direction of the main cutting edge and the direction of the auxiliary cutting edge, which leads to the aforementioned advantages (positive cutting angle, improvement in chip breaking, and as a result, an extended service life).

[0021] Preferably, both the main cutting edge and the auxiliary cutting edge are configured to be linear (not curved) in each case.

[0022] According to another improvement example, a cantilever arm is provided that extends substantially along the longitudinal axis of the cutting insert, and the cutting member extends so as to protrude laterally from the cutting head.

[0023] Preferably, the diameter of the cantilever arm or its lateral extent (the extent lateral to the longitudinal axis of the cutting insert) is configured to be thinner than the corresponding diameter or the corresponding lateral extent of the cutting head and the clamping part.

[0024] According to another improvement example, the coolant channel is directed parallel to the longitudinal axis of the cutting insert.

[0025] The coolant jet discharged from the coolant channel arranged in the clamping part consequently extends parallel along the cantilever arm and hits the cutting member parallel to the longitudinal axis of the cutting insert in the region of the chip-breaking geometry part.

[0026] Due to the relative orientation of such a coolant jet and the individual components of the cutting insert, it is further preferred that the clamping part has at least one clamping surface on its outer side that is oriented parallel to the longitudinal axis of the cutting insert.

[0027] According to another improvement example, the chip breaking geometry part is preferably a raised geometry part protruding from the rake face.

[0028] In this example, the chip breaking geometry part protrudes upward from the rake face. Thereby, the chip breaking characteristics are further improved.

[0029] According to another improvement example, the part constituting the cutting head preferably covers at least 10% of the cross-section of the cutting channel when viewed in plan view from the front face along the longitudinal axis of the cutting insert.

[0030] As already described, this covering enables at least one cutting member, particularly the chip breaking geometry part and the rake face arranged therein, to supply the coolant / lubricant in an optimal manner.

[0031] When viewed from the front face along the longitudinal axis of the cutting insert, the part of the cutting head including the chip breaking geometry part covers at least 10% of the cross-section of the coolant channel, and more preferably covers up to 80% of the cross-section of the coolant channel.

[0032] If the cutting head covers more than 80% of the cross-section of the coolant channel, since most of the coolant has already collided with the cutting head at other locations beforehand, proper cooling and lubrication of at least one cutting member cannot be ensured.

[0033] In another improvement example, it is provided that the central axis of the coolant channel is oriented parallel to the surface part of the chip breaking geometry part or lies in a plane with this surface part.

[0034] As a result, the coolant jet hits the surface part of the above-mentioned chip breaking geometry part in a parallel or tangential direction. This leads to optimal cooling and lubrication of at least one cutting member. Also, the removal of the chip is improved by this type of orientation of the coolant jet.

[0035] According to another improvement example, the cross-section of the coolant channel is non-circular. Of course, the cross-section of the coolant channel may be configured to be round (circular).

[0036] As a result of the non-circular configuration, for example, as a result of the cross-section of the coolant channel being elliptical or oval-shaped, the coolant jet can be directed in a better direction with respect to at least one cutting member.

[0037] According to another improvement example, the cross-section of the coolant channel at the first end facing away from the cutting head of the coolant channel is larger than the cross-section of the second end facing the cutting head of the coolant channel. According to this embodiment, the coolant channel can be configured, for example, in a conical taper shape. Alternatively, the coolant channel may be in the form of a recessed hole having portions of different diameters inside it.

[0038] The decrease in the diameter of the coolant channel from the first end to the second end results in a certain nozzle effect, whereby the discharge speed of the coolant channel can be increased. This is again advantageous with respect to the improvement of chip removal.

[0039] Of course, the features described above and those to be described below can be used not only in the combinations described in each case, but also in other combinations or alone without departing from the scope of the present invention.

Brief Description of the Drawings

[0040] Exemplary embodiments of the present invention are shown in the drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0041] FIGS. 1 and 3 to 6 show exemplary embodiments of the cutting insert according to the present invention in various drawings. The cutting insert is designated as a whole by reference numeral 10. FIG. 2 shows an exemplary embodiment of a tool according to the present invention, comprising a cutting insert and a cutting insert holder associated therewith. The tool is designated as a whole by reference numeral 100.

[0042] The cutting insert 10 shown in FIG. 1 is a cutting insert for a reamer tool. The cutting insert 10 has a clamp portion 12, a cutting head 14, and a cantilever arm 16. The cutting insert 10 is integrally formed. Thus, the cutting insert 10 is one piece, and the clamp portion 12, the cutting head 14, and the cantilever arm 16 are connected to each other in an integral manner. The cutting insert 10 is desirably made entirely of hard metal.

[0043] The clamp portion 12 serves to clamp the cutting insert 10 to the cutting insert holder 18 (see FIG. 2). In the embodiment shown in this example, the clamp portion is configured in a cylindrical shape. Accordingly, the cutting insert receiving member 20 provided in the cutting insert holder 18 also has a cylindrical cross section. However, it is obvious that the clamp portion 12 and the cutting insert receiving member 20 can have any other cross-sectional shape (for example, rectangular, square, oval or complex shape).

[0044] The cutting insert receiving member 20 provided within the cutting insert holder 18 is preferably in the form of a pot-shaped receiving member into which the cutting insert 10 can be introduced from the front side. In order to fix the cutting insert 10 to the cutting insert receiving member 20, screws or other fixing means may be provided. In the assembled state, the clamp portion 12 of the cutting insert 10 preferably abuts along its periphery, and the rear side 22 of its end abuts against the corresponding mating abutment surface within the cutting insert receiving member 20. Also, instead of complete abutment, partial abutment can be provided against the periphery of the clamp portion 12.

[0045] The cutting insert holder 18 is schematically shown in FIG. 2. The cutting insert holder 18 may be a conventional tool holder. Similarly, the cutting insert holder 18 may be part of a machine tool in which the cutting insert 10 is used. For example, in the latter case, the cutting insert holder 18 is a clamp chuck directly integrated with the machine tool.

[0046] In this exemplary embodiment, the cutting head 14 has five cutting members 24 that project laterally from the cutting head 14. Each of these cutting members 24 has a main cutting edge 26 and an auxiliary cutting edge 28 that is adjacent to the main cutting edge 26 and extends laterally with respect to the main cutting edge 26 (see FIGS. 3 - 4). The main cutting edge 26 and the auxiliary cutting edge 28 are in the form of straight cutting edges in the exemplary embodiment shown in this example. The main cutting edge 26 and the auxiliary cutting edge 28 are adjacent inwardly by a clamping surface 30, which can be seen in detail particularly in FIG. 4.

[0047] The chip breaking geometry portion 32 is actually often also referred to as a chip guiding step, which is disposed on the rake face 30.

[0048] The chip-breaking geometric shape portion 32 is configured to cut a chip (not shown) machined by the main cutting edge 26. This is substantially done by deforming the chip. The chip machined by the main cutting edge 26 is deflected by the chip-breaking geometric shape portion 32, thereby being further strongly curved and thereby being forced to break.

[0049] In the embodiment shown in this example, the chip-breaking geometric shape portion 32 is an upward geometric shape portion that protrudes upward from the rake face 30. However, in principle, it is also possible to configure the chip-breaking geometric shape portion as a concave structure introduced into the rake face 30.

[0050] The cutting head 14 can also be provided with five or more or five or fewer of these cutting members 24 according to the use and configuration of the cutting insert 10. For example, the cutting head 14 of the cutting insert 10 according to the present invention may be composed of only one cutting member 24. This mainly applies when the cutting insert 10 according to the present invention is used for a rotary tool. Of course, the cutting head 14 when used as a cutting insert for a rotary tool has a very different shape from that of the embodiment shown in this example.

[0051] In the present embodiment, five coolant channels 34 that serve to supply a coolant to the cutting head 14 are arranged in the clamp portion 12 according to the number of the cutting members 24. From these coolant channels 34, one coolant jet is discharged in each case and is directed at one of the cutting members 24 in each case. These coolant jets preferably strike the cutting head 14 as free jets without being split or redirected by the cantilever arm 16. Therefore, the cantilever arm 16 connecting the clamp portion 12 to the cutting head 14 preferably has a smaller diameter than the clamp portion 12 and the cutting head 14. The cantilever arm 16 extends substantially along the longitudinal axis 38 of the cutting insert 10.

[0052] The supply of coolant to each coolant channel 34 is carried out via the cutting insert holder 18. For this purpose, for example, a coolant channel 36 that supplies coolant to all the coolant channels 34 provided in the cutting insert 10 together is provided in the cutting insert holder 18. However, alternatively, a plurality of coolant channels 36 that supply coolant to the coolant channels 34 provided in the cutting insert 10 individually may be provided in the cutting insert holder 18. In this regard, it should also be noted that in the case of the configuration of the cutting head having only a single cutting member 24, preferably only one coolant channel is provided inside the clamp portion 12.

[0053] Each coolant channel 34 preferably extends parallel to the longitudinal axis 38 of the cutting insert 10. Each of the coolant channels 34 has the shape of a through-hole penetrating the clamp portion 12. Each through-hole has a contour that is completely closed on the circumference. Therefore, in each case, the coolant channel 34 is closed on the circumference so that coolant is not discharged laterally from the clamp portion 12 of the cutting insert 10.

[0054] The arrangement of the coolant channels 34 with respect to the cutting member 24 is described in more detail below. This is carried out using an example of the coolant channel 34 or the cutting member 24.

[0055] The coolant channels 34 are arranged so as to be at least partially concealed by the cutting member 24 associated with the coolant channels 34 in a plan view from the front face of the cutting insert as shown in FIGS. 5 and 6. In this case, the coolant channels 34 are particularly concealed by the portion of the cutting member 24 where the chip breaking geometry 32 is arranged. Preferably, when viewed as a plan view from the front face along the longitudinal axis 38 of the cutting insert 10, a part of the cutting member 24 including the chip breaking geometry 32 covers at least 10% of the cross-section of the coolant channel 34, but at most 80% of the cross-section of the coolant channel 34. Thereby, optimal cooling and lubrication of the components of the cutting head 14 used in the machining operation are ensured.

[0056] The cutting element 24 and the chip-breaking geometry portion 32 disposed thereon are preferably arranged to be radially offset outwardly with respect to the coolant channel 34. It is particularly preferred that the central axis 40 of the coolant channel 34 is oriented parallel to the surface portion 42 of the chip-breaking geometry portion. Further, the above-mentioned surface portion 42 disposed above the chip-breaking geometry portion 32 may be disposed in the same plane as the central axis 40 of the coolant channel 34.

[0057] As a result of the coating of the above-mentioned coolant channel 34, a part of the coolant jet discharged from the coolant channel 34 hits the rear side of the cutting head 14. Nevertheless, such an arrangement of the coolant channel 34 with respect to the cutting head 14 has been found to ensure optimal cooling and lubrication and also optimal chip removal. This is because the coolant can flow around the cutting head 14 or its cutting element 24 in an optimal manner.

[0058] Various other optimizations of the cutting insert 10 are possible. The coolant channel 34 does not necessarily have to be configured with a circular cross-section. For example, an oval or elliptical cross-section is also conceivable in order to configure the coolant jet in the most "flat" way possible. The cross-section of the coolant channel 34 may be provided to be tapered from a first end facing away from the cutting head 14 towards a second end facing the cutting head 14. Thereby, a nozzle effect of the type in which the coolant is accelerated within the coolant channel 34 is achieved. Alternatively, the coolant channel 34 may be recessed or stepped on its inner side, for example, the first portion adjacent to the first end has a larger diameter and the second portion adjacent to the second end has a smaller diameter. For various other adaptations, particularly with respect to the shape of the cutting head 14, as already mentioned, it is possible depending on the use of the cutting insert 10.

Claims

1. A cutting insert (10) for a tool (100) for machining a workpiece, comprising at least one coolant channel (34) configured as a through-hole for discharging a coolant jet, and a clamping portion (12) that serves to removably fix the cutting insert (10) to a cutting insert holder (18) of the tool (100); a cutting head (14) having at least one cutting member (24) comprising a main cutting edge (26), a rake face (30) adjacent to the main cutting edge (26), and a chip-breaking geometry portion (32) configured to break chips protruding from the rake face (30) or introduced into the rake face (30) and machined by the main cutting edge (26); a cantilever arm (16) extending along the longitudinal axis (38) of the cutting insert (10), connecting the clamping portion (12) to the cutting head (14), and having a diameter smaller than that of the clamping portion (12); The cutting insert (10) is formed in one piece such that the clamping portion (12), the cutting head (14), and the cantilever arm (16) are integrally connected; A part of the cutting head (14) having the chip-breaking geometry portion (32) covers at least 10% of the cross-section of the coolant channel (34), but at most 80% of the maximum cross-section, as viewed along the longitudinal axis (38) of the cutting insert (10). The cutting insert (10) is characterized by this.

2. The cutting insert according to claim 1, wherein the cantilever arm (16) does not cover the coolant channel (34) in a plan view from the front side along the longitudinal axis (38) of the cutting insert (10).

3. The cutting insert according to claim 1, wherein the chip-breaking geometry portion (32) is spaced apart from the main cutting edge (26), and a first portion of the rake face (30) extends along the main cutting edge (26) between the chip-breaking geometry portion (32) and the main cutting edge (26).

4. The cutting insert according to claim 3, wherein the cutting member (24) further includes an auxiliary cutting edge (28) oriented transversely to the main cutting edge (26), and a second portion of the rake face (30) extends along the auxiliary cutting edge (28) between the chip-breaking geometry portion (32) and the auxiliary cutting edge (28).

5. The cutting insert according to claim 4, wherein the main cutting edge (26) and / or the auxiliary cutting edge (28) is linear.

6. The cutting insert according to claim 1, wherein the cantilever arm (16) extends along the longitudinal axis (38) of the cutting insert (10), the cutting member (24) protrudes transversely with respect to the longitudinal axis (38), and protrudes transversely from the cutting head (14).

7. The cutting insert according to claim 1, wherein the coolant channel (34) is oriented parallel to the longitudinal axis (38) of the cutting insert (10).

8. The cutting insert according to claim 1, wherein the chip-breaking geometry is configured as a raised shape (32) protruding from the rake face (30).

9. The cutting insert according to claim 1, wherein the central axis (40) of the coolant channel (34) is oriented parallel to the surface portion (42) of the chip-breaking geometry (32) or is located in the plane of this surface portion (42).

10. The cutting insert according to claim 1, wherein the cross-section of the coolant channel (34) is non-circular.

11. The cutting insert according to claim 1, wherein the cross-section of the coolant channel (34) at the first end facing away from the cutting head (14) is larger than the cross-section of the coolant channel (34) at the second end of the coolant channel (34) facing the cutting head (14).

12. A tool (100) for machining a workpiece, comprising the cutting insert (10) according to any one of claims 1 to 11 and a cutting insert holder (18) for holding the cutting insert (10).

Images