Cutting inserts and tools for machining

Abstract

The invention relates to a cutting insert (10) of a tool (100) for machining a workpiece. The cutting insert (10) comprises a clamping portion (12) comprising at least one coolant channel (34) designed as a through-hole. Furthermore, the cutting insert (10) comprises a cutting head (14) having at least one cutting body (24) comprising a main cutting edge (26), a clearance face (30) adjacent to the main cutting edge (26), and a chip-breaker geometry (32) protruding from or being introduced into the clearance face (30) and being configured to break a chip piece lifted by the main cutting edge (26). Furthermore, the cutting insert (10) comprises a cantilever (16) connecting the clamping portion (12) to the cutting head (14) and having a smaller diameter than the clamping portion (12). When viewed in plan view from a front side along a longitudinal axis (38) of the cutting insert (10), a portion of the cutting head (14) comprising the chip-breaker geometry (32) at least partially covers the coolant channel (34).

Description

Technical Field

[0001] This invention relates to a cutting insert for a tool used in machining workpieces. The invention also relates to a tool having such a cutting insert. Background Technology

[0002] The cutting tool according to the invention can be, for example, a reaming tool. However, the invention is not limited to such reaming tools. The cutting tool according to the invention, in which a cutting insert according to the invention is inserted, can also be different types of cutting tools, such as turning tools, drilling tools, milling tools, etc. The cutting tool according to the invention is preferably used in machine tools (such as, for example, CNC machining centers).

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

[0004] The central objective of using such tools is to generate the best possible chip breaking to avoid unwanted long chip fragments during machining. Good chip breaking performance not only extends the service life of the cutting inserts used in the tool, but also has a positive impact on the surface properties of the machined workpiece.

[0005] To increase service life and improve process reliability, sufficient coolant / lubricant (hereinafter referred to as "coolant") must be supplied to the machining location. Therefore, coolant channels are typically integrated into the tool and / or cutting inserts. They are designed to ensure that the areas of the tool most heavily loaded receive an adequate supply of coolant at all times during use.

[0006] Examples of machining tools with an integrated coolant channel are disclosed in the following documents: DE102007023167A1, DE102010002669A1, DE102010021520A1, DE102010051377A1, DE202004008566U1, EP2146816B1, EP2148757B1 and EP2550126B1. Summary of the Invention

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

[0008] According to the present invention, this objective is achieved by a cutting insert comprising:

[0009] - Clamping portion, said clamping portion including at least one coolant channel configured as a through hole;

[0010] - A cutting head having at least one cutting element comprising a main cutting edge, a rake face adjacent to the main cutting edge, and a chip-breaking geometry protruding from or introduced into the rake face, the chip-breaking geometry being configured to break chips machined by the main cutting edge; and

[0011] - A cantilever that connects the clamping portion to the cutting head, and the diameter of the cantilever is smaller than that of the clamping portion;

[0012] When viewed from the front in a plan view along the longitudinal axis of the cutting insert, the portion of the cutting head that includes the chip-breaking geometry at least partially covers the coolant channels.

[0013] Due to the geometry disposed on the at least one cutting member, the chip-breaking characteristics of the cutting insert according to the invention are significantly improved. Furthermore, the geometric coverage of the coolant channel by the portion of the cutting head on which the chip-breaking geometry is arranged ensures optimal coolant supply. Compared to the typical case of prior art cutting inserts, this ensures that the coolant reaches the location of the cutting insert that plays a decisive role in chip-breaking performance. This is because most of the coolant discharged from the coolant channel thus directly impacts the chip-breaking geometry and does not spray outside the cutting member of the cutting insert or laterally cross it as is usually the case.

[0014] Because the aforementioned chip-breaking geometry geometrically covers the coolant channels (which occurs in the front plan view), it is acceptable that the coolant jet exiting the coolant channels partially collides with and is thus partially redirected by the cutting head. However, it has been found that this arrangement of the present invention results in significantly improved chip-forming properties compared to cutting inserts and tools in which the coolant jet is sprayed completely freely (i.e., not in a redirected manner) above the insert at the front. In summary, improved chip breaking and a higher level of process reliability can be achieved due to the construction of the cutting insert according to the present invention.

[0015] Therefore, the above objectives are fully achieved.

[0016] Preferably, the cutting insert is constructed in a monolithic manner, that is, a one-piece construction, in which the clamping part, the cutting head and the cantilever are integrally connected to each other.

[0017] This increases the mechanical stability of the cutting insert, which is particularly advantageous when the size of the cutting insert is relatively small.

[0018] According to another improvement, when viewed from the front in a plan view along the longitudinal axis of the cutting insert, the cantilever preferably does not cover the coolant passage.

[0019] This has the following advantages: the coolant jet exiting from the coolant channel flows out from the clamping part and reaches the cutting head freely without colliding with the cantilever or being deflected by the cantilever. Therefore, the coolant jet retains most of its kinetic energy until it comes into contact with the impact point of the chip-breaking geometry arranged on the cutting head.

[0020] According to another improvement, the chip breaker geometry is configured to be spaced apart from the main cutting edge, and a first portion of the rake face is configured to extend along the main cutting edge between the chip breaker geometry and the main cutting edge.

[0021] This allows for a positive cutting angle, which further improves chip breaking performance. This is particularly advantageous for reaming tools or other cutting tools that typically produce very thin chips. Without the aforementioned positive cutting angle combined with the chip breaking geometry according to the invention, such thin chips would not break reliably enough. This would result in scratching of the cutting surface and, consequently, the rake face, ultimately increasing wear and shortening the life of the cutting insert.

[0022] According to another improvement, the cutting component also includes an auxiliary cutting edge oriented laterally relative to the main cutting edge, wherein a second portion of the rake face extends along the auxiliary cutting edge between the chip breaking geometry and the auxiliary cutting edge.

[0023] The term "laterally" in this case describes the orientation of the two cutting edges at an angle not equal to 0°. The two cutting edges (the primary cutting edge and the secondary cutting edge) are preferably oriented at an acute or right angle relative to each other. However, in principle, orientation at an obtuse angle relative to each other is also possible.

[0024] Based on the aforementioned improvements, the chip breaker geometry 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, improved chip breaking, and thus extended service life).

[0025] Preferably, both the primary cutting edge and the secondary cutting edge are constructed in a rectilinear manner (without bending) in each case.

[0026] According to another improvement, the cantilever is configured to extend substantially along the longitudinal axis of the cutting insert, and such that the cutting member protrudes laterally from the cutting head relative to the cutting head.

[0027] Preferably, the diameter of the cantilever or its lateral length (the length lateral to the longitudinal axis of the cutting insert) is configured to be thinner than the corresponding diameter or lateral length of the cutting head and the clamping portion.

[0028] According to another improvement, the coolant channel is oriented parallel to the longitudinal axis of the cutting insert.

[0029] The coolant jet discharged from the coolant channels arranged in the clamping section thus extends parallel to the cantilever and impacts the cutting element parallel to the longitudinal axis of the cutting insert in the region of the chip-breaking geometry.

[0030] In the case of this type of orientation of the coolant jet and the various components of the cutting insert relative to each other, it is further preferred that the clamping portion has at least one clamping surface on its outer side, which is oriented parallel to the longitudinal axis of the cutting insert.

[0031] According to another improvement, the chip breaking geometry is preferably in the form of a raised geometry that protrudes from the rake face.

[0032] In this configuration, the chip-breaking geometry protrudes upwards from the rake face. This further improves chip-breaking performance.

[0033] According to another improvement, preferably, when viewed from the front in a plan view along the longitudinal axis of the cutting insert, the portion of the cutting head including the chip-breaking geometry covers at least 10% of the cross-section of the coolant channel.

[0034] As already mentioned, this cover allows the at least one cutting element (particularly the chip breaker geometry and rake face arranged therein) to be supplied with coolant / lubricant in an optimal manner.

[0035] More preferably, when viewed from the front in a plan view along the longitudinal axis of the cutting insert, the portion of the cutting head including the chip-breaking geometry covers at least 10% but at most 80% of the cross-section of the coolant channel.

[0036] If the cutting head covers more than 80% of the cross-section of the coolant channel, adequate cooling and lubrication of at least one cutting component will no longer be guaranteed, because most of the coolant has already collided with the cutting head at another location.

[0037] In another improvement, the central axis of the coolant channel is set to be parallel to oriented to the surface portion of the chip-breaking geometry or to lie in the same plane as that surface portion.

[0038] This causes the coolant jet to impact the aforementioned surface portion of the chip-breaking geometry in a parallel or even tangential manner. This results in optimal cooling and lubrication of the at least one cutting component. This type of orientation of the coolant jet also improves chip removal.

[0039] In another improvement, the cross-section of the coolant passage is non-circular. Of course, the cross-section of the coolant passage can also be constructed to be circular.

[0040] Due to its non-circular construction, for example, due to the elliptical or oval construction of the coolant channel cross-section, the coolant jet can be oriented even better relative to the at least one cutting member.

[0041] According to another improvement, the cross-section of the coolant channel at a first end away from the cutting head is larger than the cross-section at a second end facing the cutting head. According to this embodiment, the coolant channel can be constructed, for example, in a tapered manner. Alternatively, the coolant channel can be in the form of recesses with portions of different diameters within its interior.

[0042] The decrease in coolant passage diameter from its first end to its second end creates a nozzle effect, which increases the discharge velocity of the coolant passage. This is also beneficial for improving debris removal.

[0043] Of course, the features mentioned above and explained below can be used not only in the combinations described in each case, but also in other combinations or individually, without departing from the scope of the invention. Attached Figure Description

[0044] The accompanying drawings illustrate exemplary embodiments of the present invention. In the drawings:

[0045] Figure 1 A perspective view of an exemplary embodiment of the cutting insert according to the present invention is shown.

[0046] Figure 2 A side view of an exemplary embodiment of a cutting tool according to the invention is shown, the tool having a cutting insert according to the invention and a cutting insert retainer schematically shown in cross-section.

[0047] Figure 3 It shows Figure 1 A partial view of the cutting head of the cutting insert according to the present invention;

[0048] Figure 4 It shows Figure 3 A detailed view of the cutting components of the cutting head shown;

[0049] Figure 5 It shows Figure 1 The front plan view of the cut insert shown; and

[0050] Figure 6 Showing Figure 5 Details. Detailed Implementation

[0051] Figure 1 as well as Figures 3 to 6An exemplary embodiment of the cutting insert according to the invention is shown in different views. The cutting insert as a whole is indicated by 10. Figure 2 An exemplary embodiment of a cutting tool according to the invention is shown, the tool including a cutting insert and an associated cutting insert retainer. The entire tool is indicated by 100.

[0052] Figure 1 The cutting insert 10 shown is a cutting insert for a reaming tool. The cutting insert 10 has a clamping portion 12, a cutting head 14, and a cantilever 16. The cutting insert 10 is configured as a single unit. Therefore, it comprises one piece, wherein the clamping portion 12, the cutting head 14, and the cantilever 16 are integrally connected to each other. The cutting head 10 is preferably made entirely of cemented carbide.

[0053] Clamping portion 12 is used to clamp the cutting insert 10 in the cutting insert retainer 18 (see...) Figure 2 In the exemplary embodiment shown in this case, the clamping portion is constructed in a cylindrical manner. Therefore, the cutting insert receiving member 20 disposed in the cutting insert holder 18 also has a cylindrical cross-section. However, it is self-evident that the clamping portion 12 and the cutting insert receiving member 20 may have any other cross-sectional shape (e.g., shaped as a rectangle, square, ellipse, or in a complex manner).

[0054] The cutting insert receiving member 20 disposed in the cutting insert holder 18 is preferably in the form of a can-shaped receiving member into which the cutting insert 10 can be introduced from the front side b. Screws or other fastening devices may be provided to secure the cutting insert 10 in the cutting insert receiving member 20. In the assembled state, the clamping portion 12 of the cutting insert 10 preferably abuts along its outer periphery and its rear end 22 abuts against the corresponding abutting surface in the cutting insert receiving member 20. Instead of complete abutment, partial abutment against the outer periphery of the clamping portion 12 may also be provided.

[0055] The cut insert retainer 18 is schematically shown in Figure 2 The cutting insert retainer 18 can be a conventional tool retainer. Similarly, the cutting insert retainer 18 can also be part of the machine tool in which the cutting insert 10 is used. For example, in the latter case, the cutting insert retainer 18 is a clamping chuck directly integrated into the machine tool.

[0056] In the exemplary embodiment shown in this example, 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 primary cutting edge 26 and an auxiliary cutting edge 28 that is adjacent to and extends laterally relative to the primary cutting edge 26 (see [link to example]). Figure 3-4In the exemplary embodiment shown in this example, the main cutting edge 26 and the auxiliary cutting edge 28 are in the form of linear cutting edges. The main cutting edge 26 and the auxiliary cutting edge 28 are abutted inwardly by a clamping surface 30, which is particularly suitable for... Figure 4 As seen in the details shown.

[0057] A chip-breaking geometry 32 is arranged on the rake face 30, which is often referred to as a chip guide step in practice.

[0058] The chip-breaking geometry 32 is configured to cause the chip fragments (not shown) machined by the main cutting edge 26 to break. This is essentially achieved through chip fragment deformation. The chip fragments machined at the main cutting edge 26 are redirected by the chip-breaking geometry 32, thereby being more forcefully bent and thus forced to break.

[0059] In the embodiment shown in this example, the chip breaker geometry 32 is in the form of a raised geometry protruding upward from the rake face 30. However, in principle, the chip breaker geometry can also be constructed as a recessed structure introduced into the rake face 30.

[0060] Depending on the type of use and construction of the cutting insert 10, the cutting head 14 may also include more or fewer than five of these cutting elements 24. For example, the cutting head 14 of the cutting insert 10 according to the invention may also include only one cutting element 24. This is generally the case, especially when the cutting insert 10 according to the invention is used in a lathe tool. Of course, the cutting head 14 is shaped very differently when used as a lathe tool cutting insert than the cutting head in the exemplary embodiment shown in this example.

[0061] In this exemplary embodiment, five coolant channels 34 are arranged in the clamping portion 12, depending on the number of cutting members 24, for supplying coolant to the cutting head 14. In each case, a coolant jet is discharged from these coolant channels 34, and the coolant jet is oriented relative to one of the cutting members 24 in each case. These coolant jets preferably impinge on the cutting head 14 as free jets without being deflected or redirected by the cantilever 16. The cantilever 16 (which connects the clamping portion 12 to the cutting head 14) therefore preferably has a smaller diameter than the clamping portion 12 and the cutting head 14. The cantilever 16 extends substantially along the longitudinal axis 38 of the cutting insert 10.

[0062] Coolant supply to each coolant channel 34 is performed via the cutting insert holder 18. For this purpose, for example, a coolant channel 36 is provided in the cutting insert holder 18, which supplies coolant to all the coolant channels 34 provided in the cutting insert 10 together. However, alternatively, multiple coolant channels 36 may be provided in the cutting insert holder 18, which supply coolant to the coolant channels 34 provided in the cutting insert 10 individually. In this regard, it should be noted again that, in the case where the cutting head has only a single cutting member 24, preferably, only one coolant channel is also provided inside the clamping portion 12.

[0063] Each coolant channel 34 preferably extends parallel to the longitudinal axis 38 of the cutting insert 10. Each coolant channel 34 is in the form of a through-hole extending through the clamping portion 12. Each through-hole has a profile that is completely closed at the outer periphery. Therefore, the coolant channel 34 is closed at the outer periphery in each case, so that coolant cannot be discharged laterally from the clamping portion 12 of the cutting insert 10.

[0064] The arrangement of the coolant passage 34 relative to the cutting member 24 will be discussed in more detail below. This is done using an example of either the coolant passage 34 or the cutting head 24.

[0065] The coolant passage 34 is arranged in such a way that, in a plan view viewed from the front of the cutting insert, as shown... Figure 5 and Figure 6 As shown, it is at least partially hidden by the associated cutting member 24. In this example, the coolant channel 34 is specifically hidden by the portion of the cutting member 24 on which the chip-breaking geometry 32 is arranged. Preferably, the portion of the cutting member 24 including the chip-breaking geometry 32, when viewed from the front as a plan view along the longitudinal axis 38 of the cutting insert 10, covers at least 10% but at most 80% of the cross-section of the coolant channel 34. This ensures optimal cooling and lubrication of the components of the cutting head 14 used in the machining process.

[0066] The cutting member 24 and the chip-breaking geometry 32 disposed thereon are preferably arranged to be radially outwardly offset relative to the coolant passage 34. Particularly preferred is that the central axis 40 of the coolant passage 34 is oriented parallel to the surface portion 42 of the chip-breaking geometry. The aforementioned surface portion 42 located on the upper side of the chip-breaking geometry 32 may also be arranged in a plane together with the central axis 40 of the coolant passage 34.

[0067] Although a portion of the coolant jet discharged from the coolant channel 34 impacts the rear side of the cutting head 14 due to the aforementioned coverage of the coolant channel 34, it has been found that this arrangement of the coolant channel 34 relative to the cutting head 14 ensures optimal cooling and lubrication as well as optimal chip removal, because the coolant can therefore flow around the cutting head 14 or its cutting member 24 in an optimal manner.

[0068] Various other optimizations of the cutting insert 10 are possible. The coolant channel 34 does not necessarily have to be constructed with a circular cross-section. For example, an oval or elliptical cross-section can also be envisioned to construct the coolant jet in a "flat" manner as much as possible. The cross-section of the coolant channel 34 can also be configured to gradually taper from its first end away from the cutting head 14 toward its second end facing the cutting head 14. This achieves a type of nozzle effect by which the coolant is accelerated within the coolant channel 34. Alternatively, the coolant channel 34 can also be recessed or stepped, such that, 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. As already mentioned, various other modifications, particularly the shape of the cutting head 14, are also possible depending on the application of the cutting insert 10.

Claims

1. A cutting insert (10) for machining a tool (100) of a workpiece, wherein, The cutting insert (10) includes: - Clamping portion (12), the clamping portion including at least one coolant channel (34), the coolant channel being configured as a through hole; - A cutting head (14) having at least one cutting member (24) including a main cutting edge (26), a rake face (30) adjacent to the main cutting edge (26), and a chip breaking geometry (32) arranged on the rake face (30) as a protruding geometry projecting from the rake face (30), or introduced into the rake face (30) and configured to break chips machined by the main cutting edge (26); and - A cantilever (16) extends along the longitudinal axis (38) of the cutting insert (10) and connects the clamping portion (12) to the cutting head (14), and the diameter of the cantilever is smaller than that of the clamping portion (12). The cutting insert (10) is constructed integrally, such that the clamping part (12), the cutting head (14), and the cantilever (16) are integrally connected to each other; and When viewed from the front along the longitudinal axis of the cutting insert (10), a portion of the cutting head (14) including the chip-breaking geometry (32) covers at least 10% but at most 80% of the cross-section of the coolant channel (34).

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

3. The cutting insert according to claim 1, wherein, The chip breaker geometry (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 between the chip breaker geometry (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 laterally relative to the main cutting edge (26), wherein a second portion of the rake face (30) extends along the auxiliary cutting edge (28) between the chip breaking geometry (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) are straight.

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

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 central axis (40) of the coolant channel (34) is oriented parallel to the surface portion (42) of the chip breaking geometry (32), or lies in the same plane as the surface portion (42).

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

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

11. A cutting tool (100) for machining a workpiece, the cutting tool having a cutting insert (10) according to any one of claims 1 to 10 and a cutting insert retainer (18) for retaining the cutting insert (10).

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