Cutting insert and machine tool

Abstract

Cutting inserts and machine tools are disclosed. A cutting insert (14) for a machine tool is described, the cutting insert having a cutting edge (26) and a flute (30) extending along the cutting edge (26). A chip breaker element (48) protruding inside the flute (30) is seated in the flute (30). The chip breaker element comprises a chip guiding surface (50), and each point of the chip guiding surface (50) has a distance to the flute profile which is greater than zero. The chip guiding surface (50) further extends parallel to the flute profile and / or is curved in two directions. A machine tool having such a cutting insert (14) is also presented.

Description

Technical Field

[0001] The present invention relates to a cutting insert for a machine tool, the cutting insert having a cutting edge and a chip groove extending along the cutting edge, wherein a chip breaker element protruding into the chip groove is disposed in the chip groove.

[0002] The present invention further relates to a machine tool, specifically a turning tool, that includes such cutting inserts. Background Technology

[0003] Such machine tools and cutting inserts are known in the prior art. They are typically designed so that the chip flutes separate the cutting edge from the fastening portion of the cutting insert. In other words, the chip flutes are positioned as groove-like recesses between the cutting edge and the fastening portion of the cutting insert. Naturally, the chip flutes and the rake face are located on the same side of the cutting edge.

[0004] Chip breakers are typically used to create a multidimensional stress state within the chip that has detached from the workpiece by means of a cutting blade, thereby causing the chip to break.

[0005] Of course, chip breaker elements can provide only relatively low resistance to the chip flow away from the workpiece, so that the chip breaker elements do not prevent chips from flowing away from the workpiece. Therefore, chip breaker elements must always be designed for a stress field conducive to good chip breakage, which is facilitated by relatively large chip breaker elements, and for reliable chip evacuation from the workpiece, which is facilitated by relatively small chip breaker elements. Summary of the Invention

[0006] The objective of this invention is to further improve such cutting inserts and associated machine tools. The aim is to eliminate or at least mitigate the conflict between reliable chip breakage and low-resistance chip evacuation. Therefore, a cutting insert should be specified, by means of which chips can be easily guided away from the machined workpiece while reliably breaking.

[0007] The objective is achieved using a cutting insert of the type described above, wherein the chip breaker element includes a chip guiding surface, and the distance between each point of the chip guiding surface and the flute contour is greater than zero. The chip guiding surface also extends parallel to the flute contour and / or curves in two directions. In other words, the chip guiding surface of the chip breaker element rises from the flute contour. Of course, the chip guiding surface can transition into the flute contour via one or more transition surfaces. However, the transition surfaces must then be designed such that at least some points of the transition surfaces overlap with the flute contour. Therefore, these points are not spaced apart from the flute contour and are therefore not considered as chip guiding surfaces. When the chip guiding surface is viewed along the course of the flute, the parallel course of the chip guiding surface and the flute contour can be seen particularly clearly. The distance between the chip guiding surface and the flute contour is then constant. If the flute contour is curved, the chip guiding surface in the variant is also curved. Alternatively or additionally, if the chip-guiding surface is curved along a second direction, this curvature preferably appears as a straight line oriented along the path of the chip flute. In this context, curvature is understood as a deviation from a straight path. Such chip breaker elements present only relatively low resistance to the chip flow. Therefore, chips can flow away from the relatively easily machinable workpiece. At the same time, the chip-guiding surface can generate a multidimensional stress state within the chip, causing the chip to break in the desired manner. Thus, the aforementioned conflict is resolved or at least mitigated.

[0008] Of course, in this context, it is not excluded that the cutting insert according to the invention may be further equipped with other chip breaker elements that may be known in themselves. Such chip breaker elements may be disposed inside the chip groove. This can further promote chip breakage.

[0009] The cutting edge of a cutting insert can be straight or curved.

[0010] In one embodiment, the chip breaker element is spaced apart from the cutting edge of the chip groove. Therefore, the chip breaker element does not extend to the cutting edge of the chip groove. Thus, the influence of the chip breaker element on the machining process is eliminated, or at least minimized. This is especially true for the undisturbed flow of chips from the machining zone.

[0011] In a plan view, the chip breaker element can form an angle of less than 90° with the cutting edge. In other words, the chip breaker element is inclined relative to the cutting edge. Therefore, it is particularly easy to generate a multidimensional stress state within the chip so that the chip breaks in the desired manner. Furthermore, this also defines the direction in which the chip is discharged from the machining zone.

[0012] The cutting edge preferably connects two corners of the cutting insert. Corners can also be used in machining. Specifically, the cutting insert includes three or more corners, which are connected to the cutting edge in pairs.

[0013] According to one variation, the chip guide finger is disposed in the end region of one of the adjacent corners of the chip groove and positioned within the chip groove. The chip guide finger is curved in both plan view and view along the path of the chip groove. The chip guide finger also serves to guide the chip away from the processing area. Furthermore, the chip guide finger deforms the chip. Therefore, a multidimensional stress state can be generated in the chip to cause it to fracture. If there are cutting edges and chip grooves on both sides of the corner, the chip guide finger can be disposed in the two end regions of the adjacent corners of the respective chip grooves. In this case, the chip guide finger can be implemented as a two-finger element.

[0014] Advantageously, the chip guide finger is positioned closer to the associated corner than the chip breaker element. Therefore, the chip guide finger and the chip breaker element are positioned at a specific interval along the cutting edge. Consequently, chips can be easily ejected and break along the entire cutting edge.

[0015] Furthermore, the distance between the chip guide finger and the cutting edge may be smaller than the distance between the chip breaker element and the cutting edge. This is also used to reliably remove and break the chips.

[0016] At least one first chamfer can be placed at the transition from the cutting edge to the chip flute. This chamfer can be called a protective chamfer. Its purpose is to convert tensile stress into compressive stress in the rake face side region of the cutting edge, and thus protect the cutting edge from large cutting forces. This results in a longer service life for the cutting insert.

[0017] Therefore, the first chamfer can have a chamfer angle of -2° to 6° and / or a chamfer width of 0.05mm to 0.5mm.

[0018] A second chamfer, or transition radius, separate from the first chamfer, can also be provided at the transition from the cutting edge to the chip flute. Therefore, in the first variant, two chamfers are provided between the cutting edge and the chip flute, specifically differing in their angle and / or width. In the second variant, both a chamfer and a transition radius are provided. This makes it possible to achieve a particularly smooth transition between the cutting edge and the chip flute.

[0019] The chamfer angle for the second chamfer can be in the range of -2° to 6°.

[0020] The chamfer width of the second chamfer can be in the range of 0.05mm to 0.5mm.

[0021] The size of the transition radius is preferably determined by its tangential transition to the adjacent surfaces on both sides. Depending on the path of the surfaces to be joined, the size of the transition radius can vary along the cutting edge.

[0022] In one embodiment, the chamfer angle and / or chamfer width of the first chamfer and / or the chamfer angle and / or chamfer width of the second chamfer vary along the cutting edge. When the chamfer angle is generally in a negative range, the chamfer angle is preferably corrected in the corner region to reduce cutting forces, and is more negative in the central region of the cutting edge to stabilize the cutting edge. This achieves a good trade-off between long cutting tool life and high machinability.

[0023] The edges defining the first and / or second chamfers can be rounded. This facilitates a smooth transition between the cutting edge and the chip flute, which is beneficial for continuity.

[0024] The circular blade can have a radius of 0.2 mm to 1 mm.

[0025] In an alternative design, a deflection channel for the coolant is located on the upper side of the cutting insert. Therefore, the coolant can be guided via the deflection channel to the machining zone and / or the cutting edge. This allows for high cooling capacity, which is particularly suitable for depths of cut exceeding 1.5 mm.

[0026] In this context, a deflection channel specifically includes at least one deflection geometry by which the coolant jet can be deflected. For this to be achieved, the jet must strike the deflection geometry. For example, the walls of the deflection channel represent this deflection geometry. These walls are then positioned at a specific angle not parallel to the jet direction. In this case, it is essential to distinguish the deflection channel from the gap; the deflection channel is solely intended to allow the coolant jet to pass through as freely as possible.

[0027] Then, the exit end of the deflection channel can face the cutting edge. Therefore, the deflection channel can be used to guide coolant onto the cutting edge for targeted cooling. This also occurs particularly outside the corner area of ​​the cutting insert.

[0028] Alternatively or additionally, the central axis of the exit end of the deflection channel may extend parallel to a direction tangential to the chip breaker element. Therefore, coolant can be introduced relatively directly into the machining zone for cooling, preferably also cooling areas spaced apart from corners and associated corner radii. This also creates a lubricating film on the chip breaker element, reducing friction and wear as chips slide off.

[0029] The cutting insert is preferably an indexable insert. The cutting insert then includes multiple cutting edges and multiple corners. For example, this indexable insert is polygonal.

[0030] The objective is further achieved by a machine tool of the type described above, which includes a cutting insert according to the invention. The effects and advantages of the cutting insert of the cutting tool are also mentioned. Attached Figure Description

[0031] The invention is explained below with the aid of design examples shown in the accompanying drawings. The figures illustrate:

[0032] - Figure 1 A machine tool according to the invention, comprising a cutting insert according to the invention as shown in the perspective view.

[0033] - Figure 2 To isolate the perspective Figure 1 Cutting blades,

[0034] - Figure 3 In the upper side view Figure 2 Cutting blades,

[0035] - Figure 4 The bottom view of the cutting insert Figure 2 Cutting blades,

[0036] - Figure 5 For along Figure 3 In the side view of direction V in the middle Figures 2 to 4 Cutting blades,

[0037] - Figure 6 For along Figure 3 In the side view of direction VI Figures 2 to 5 Cutting blades,

[0038] - Figure 7 for Figure 2 Enlarged section VII of the cutting blade,

[0039] - Figure 8 In the plan view Figure 7 The section,

[0040] - Figure 9 For different perspectives Figure 7 The section,

[0041] - Figure 10 for Figure 2 Detailed view of the chip breaker element of the cutting blade.

[0042] - Figure 11 for Figure 10 Another detailed view of the chip breaker element.

[0043] - Figure 12 Detailed views of the chip breaker elements according to the alternative, and

[0044] - Figure 13 for Figure 12 Another detailed view of the chip breaker element. Detailed Implementation

[0045] Figure 1 Machine tool 10 is shown, which is a lathe tool in the illustrated embodiment.

[0046] The machine tool 10 includes a tool holder 12, to which cutting inserts 14 are attached.

[0047] The cutting insert 14 here is implemented as an indexable insert, which is rhomboid in plan view.

[0048] Two outlet openings 16, 18 for the coolant are additionally provided on the tool holder 12. These openings are oriented such that the corresponding coolant jets 20, 22 are directed toward the cutting blade 14. As will be explained later, the cutting blade 14 is configured such that at least the coolant jet 22 is divided into a first coolant sub-jet 22a and a second coolant sub-jet 22b.

[0049] There are a total of four cutting edges 26 on the upper side 24 of the cutting insert 14, which connect adjacent corners 28 to each other.

[0050] A recessed chip groove 30 is provided in the area of ​​the rake face of the cutting edge 26 and extends along each cutting edge of the cutting edge 26.

[0051] Therefore, the chip grooves 30 are positioned between the associated cutting edge 26 and the central fastening opening 32 of the cutting insert 14.

[0052] Since all four cutting edges 26 and the associated chip flutes 30 are configured in the same way in the example shown, there is no need to distinguish them below.

[0053] The first chamfer 34 and the second chamfer 36, which are separate from each other, are provided at the transition from the cutting edge 26 to the associated chip groove 30.

[0054] The edges defining chamfers 34 and 36 are rounded.

[0055] The first chamfer 34 in the design example shown has a chamfer angle that is substantially constant over the total length of the associated cutting edge 26.

[0056] The same applies to the chamfer width of the first chamfer 34. The chamfer width is also generally constant along the total length of the associated cutting edge 26.

[0057] Of course, in this context, the chamfer angle and / or chamfer width may also vary along the cutting edge 26, i.e., they are not constant.

[0058] In the area defining the corner 28 of the associated cutting edge 26, the second chamfer 36 is implemented accordingly with a first chamfer angle, which is different from the second chamfer angle used by the second chamfer 36 in the central area 38.

[0059] The second chamfer 36 has a steeper inclination toward the associated chip discharge groove 30 in the corner 28 area than it does in the central area 38. In other words, in terms of magnitude, the first chamfer angle is greater than the second chamfer angle.

[0060] Since both the first and second chamfer angles are negative according to conventional naming, the second chamfer angle (i.e., the chamfer angle in the central area 38) can be described as being more positive than the first chamfer angle (i.e., the chamfer angle in the area of ​​corner 28).

[0061] The chamfer width of the second chamfer 36 also varies along the associated cutting edge 26. The chamfer width of the second chamfer 36 in the corner 28 area is greater than the chamfer width in the center area 38.

[0062] In this context, the chamfer angle and chamfer width vary continuously along the associated cutting edge 26.

[0063] In other examples not shown, the second chamfer angle may alternatively be greater in magnitude than the first chamfer angle.

[0064] The cutting blade 14 is equipped with various elements for guiding and breaking the chips.

[0065] The following will refer to Figures 7 to 11 To explain these, Figures 7 to 11 The corner 28 of the cutting blade 14 is shown as an example. Other corner areas are configured in the same manner.

[0066] The chip guide finger 40 is positioned at the adjacent corner 28 of the chip groove 30, defining the end area of ​​the cutting edge 26.

[0067] Starting from the chip discharge groove profile of chip discharge groove 30, its height is 0.02mm to 0.3mm.

[0068] Furthermore, it bends in the plan view, specifically in the view of the upper side 24. This bending is caused by… Figure 8 The curvature shown is 42.

[0069] The associated radius of curvature is in the range of 0.8 mm to 6 mm.

[0070] Furthermore, in a view along the associated chip outlet 30 route 44, the chip guide finger 40 is also curved. This curvature is caused by… Figure 7 The curvature shown is 46.

[0071] The associated radius of curvature can be from 1 mm to 3 mm.

[0072] Naturally, the profile of the chip guide finger 40 can also be composed of multiple curves.

[0073] The chip guiding finger 40 is used to guide chips away from the workpiece to be machined. Furthermore, the chip guiding finger 40 also generates a multidimensional stress state within the chip to be guided away, causing the chip to fracture.

[0074] The chip breaker element 48 is further disposed on one side of the chip guide finger 40 opposite the corresponding associated corner 28.

[0075] The chip breaker element 48 is also housed in the chip discharge groove 30 and protrudes into the interior of the chip discharge groove 30.

[0076] The chip breaker element 48 includes a chip guide surface 50 that rises from the chip groove profile defining the chip groove 30.

[0077] This means that the distance between each point on the chip guide surface 50 and the chip groove profile is greater than zero. This is particularly visible in a view along the route 44 of the associated chip groove 30.

[0078] The chip discharge groove profile should be understood as the entire surface that defines the geometry of the chip discharge groove 30. Therefore, the chip discharge groove profile of the chip discharge groove 30 specifically includes the chip discharge groove bottom and the chip discharge groove wall.

[0079] exist Figures 1 to 11 In the illustrated embodiment, the chip guiding surface 50 extends parallel to the associated chip discharge groove profile.

[0080] This means that the distance between each point on the chip guide surface 50 and the chip groove profile of the chip groove 30 is approximately the same, thus assuming that the chip groove profile is still below the chip guide surface 50.

[0081] This spacing can be from 0.02mm to 0.1mm.

[0082] The chip breaker element 48 starts at the edge of the chip groove 30 opposite to the cutting edge 26 and ends at a specific distance from the cutting edge side edge of the chip groove 30.

[0083] In the plan view, the chip breaker element 48 also forms an angle 52 of approximately 50° with the cutting edge 26.

[0084] The cutting blade 14 also includes another chip breaker element 54 in the central region 38, which includes a chip guiding surface 56.

[0085] However, unlike the chip breaker element 54, the chip guiding surface 56 now extends from the chip outlet profile of the chip outlet groove 30 in a generally sloping manner.

[0086] The chip breaker elements 48 and 54 are also used to subject the chips to a multidimensional stress state, thereby promoting the breakage of the chips.

[0087] The cutting blade 14 is further provided with a deflection channel 58 for the coolant.

[0088] The deflection channel is located on the upper side 24.

[0089] Each of the deflection channels 58 includes a first end 58a facing the corresponding associated exit opening 16, 18 and a second end 58b facing the corresponding associated cutting edge 26.

[0090] Therefore, the first end 58a can also be referred to as the inlet-side end, and the second end 58b can be referred to as the outlet-side end.

[0091] The exit end 58b faces the cutting edge 26.

[0092] Furthermore, the central axis of the deflection channel 58 at its exit end 58b extends generally parallel to the direction tangential to the chip breaker element 48.

[0093] Therefore, the coolant can flow through the chip breaker element 48 with minimal obstruction.

[0094] In the illustrated embodiment, the wall 62 of the deflection channel 58 is further used to deflect a portion of the coolant jets 20, 22 (see also...). Figure 1 ).

[0095] Therefore, the first coolant sub-jet 22a is directed toward the corner 28, and the second coolant sub-jet 22b is directed toward the area of ​​the cutting edge 26 that is spaced apart from the corner 28.

[0096] Figure 12 and Figure 13 The cutting blade 14 is shown, in which the chip breaker element 48 is configured according to a variant.

[0097] The chip guiding surface 50 no longer extends parallel to the chip groove profile of the chip groove 30.

[0098] Instead, the chip guiding surface 50 is bent in two directions.

[0099] This produces curvature along the first direction 64 because the chip breaker element 48 adopts the curvature of the profile of the chip groove 30.

[0100] However, the chip guiding surface 50 is also curved along a second direction 66, which generally corresponds to the route 44 of the chip outlet groove.

[0101] In other words, the chip guiding surface 50 in the second variant deviates from a straight line along directions 64 and 66.

[0102] In this variant, the distance between the chip guide surface 50 and the chip outlet profile varies between 0.02 mm and 0.1 mm.

[0103] Naturally, the two mentioned variants of the chip-guiding surface 50 can also exist in combination.

[0104] Then, the chip guiding surface 50 extends parallel to the chip groove profile of the chip groove 30 and bends in both directions. This is possible if the chip groove profile bends in both directions and the chip guiding surface 50 extends parallel to the chip groove profile.

[0105] According to the second variant, the chip breaker element 48 is also used to subject the chip to a multidimensional stress state, and thus cause the chip to break.

[0106] As mentioned earlier, the cutting insert 14 is implemented as an indexable insert. Therefore, the lower side 68 of the cutting insert 14 can be configured in the same manner as the upper side 24.

Claims

1. A cutting insert (14) for a machine tool (10), the cutting insert having four cutting edges (26) and chip grooves (30) extending along the respective cutting edges (26), wherein a chip breaker element (48) protruding into the chip groove (30) is disposed in the chip groove (30), Its features are, The chip breaker element (48) includes a chip guiding surface (50), and each point of the chip guiding surface (50) is spaced from the chip groove profile by a distance greater than zero. The chip guiding surface (50) extends parallel to the chip groove profile and bends along two directions (64, 66) in a plan view defined by the four cutting edges (26). The first direction (64) of the two directions (64, 66) extends from one end of the chip breaker element (48) to the other end, and the second direction (66) of the two directions (64, 66) generally corresponds to the path (44) of the chip groove (30).

2. The cutting blade (14) according to claim 1, characterized in that, The chip breaker element (48) is spaced apart from the cutting edge of the chip outlet groove (30).

3. The cutting blade (14) according to claim 1 or 2, characterized in that, In a plan view defined by the four cutting edges (26), the chip breaker element (48) forms an angle (52) of less than 90° with the cutting edges (26).

4. The cutting blade (14) according to claim 1 or 2, characterized in that, The cutting edge (26) connects the two corners (28) of the cutting blade (14).

5. The cutting blade (14) according to claim 4, characterized in that, Two chip guides (40) are disposed in the end region of the chip groove (30) adjacent to one of the corners (28) and positioned in the chip groove (30), wherein the two chip guides (40) converge at their roots and the two chip guides (40) separate from the roots and bend toward the respective cutting edge (26) in both a plan view defined by the four cutting edges (26) and a view along the route (44) of the chip groove (30), such that the ends of the two chip guides (40) are close to the respective cutting edge (26).

6. The cutting blade (14) according to claim 5, characterized in that, The chip guide finger (40) is located closer to the associated corner (28) than the chip breaker element (48).

7. The cutting blade (14) according to claim 1 or 2, characterized in that, At least one first chamfer (34) is provided at the transition from the cutting edge (26) to the chip groove (30).

8. The cutting blade (14) according to claim 7, characterized in that, A second chamfer (36) or transition radius separate from the first chamfer (34) is provided at the transition from the cutting edge (26) to the chip groove (30).

9. The cutting blade (14) according to claim 8, characterized in that, The chamfer angle and / or chamfer width of the first chamfer (34) and / or the chamfer angle and / or chamfer width of the second chamfer (36) vary along the cutting edge (26).

10. The cutting blade (14) according to claim 8, characterized in that, The edges defining the first chamfer (34) and / or the second chamfer (36) are rounded.

11. The cutting blade (14) according to claim 1 or 2, characterized in that, In the installation position, a deflection channel (58) for coolant is provided on the upper side (24) of the cutting blade (14).

12. The cutting blade (14) according to claim 11, characterized in that, The exit end (58b) of the deflection channel (58) faces the cutting edge (26).

13. The cutting blade (14) according to claim 12, characterized in that, The central axis of the outlet end (58b) of the deflection channel (58) extends parallel to the direction tangential to the chip breaker element (48).

14. The cutting blade (14) according to claim 1 or 2, characterized in that, The cutting insert (14) is an indexable insert.

15. A machine tool (10) having a cutting insert (14) according to any one of the preceding claims.

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