Machining tool and method for manufacturing a machining tool

Abstract

A machining tool, in the area of a tool tip, includes an integrated cooling structure for transporting a coolant. The cooling structure is optionally or in combination designed as a porous structure or at least one cooling channel having a bent reversing segment, so that two channel segments are oriented in opposite directions. The cooling structure is integrated into a base body of a carrier tool. According to a method of the invention, the cooling structure is manufactured by means of a 3D printing method.

Claims

1. A machining tool that extends in an axial direction along a rotational axis and comprising: a tool tip; a base body, the base body forming retaining webs between which a tool tip can be inserted and having an integrated cooling structure for conducting a coolant or lubricant, the cooling structure being integrated at least partly in the retaining webs; and a chip flute formed in the base body, the chip flute having a chip flute wall, wherein the cooling structure, at least in sections, is designed as a porous structure having a plurality of pores; wherein at least a portion of the porous structure is located in the retaining webs of the base body and the porous structure exits at an outlet point provided on the chip flute wall; and wherein the porous structure has a porosity ranging between 5% and 90%.

2. The machining tool as claimed in claim 1, further comprising an outer cladding at which the porous structure exits at the outlet point.

3. The machining tool as claimed in claim 1, wherein the outlet point is a planar outlet point.

4. A method for manufacturing a machining tool as claimed in claim 1, wherein the machining tool is manufactured with an integrated cooling structure at least partially with the aid of a 3D printing method.

5. The machining tool as claimed in claim 1, wherein the pores have an average pore size ranging between 15 and 45 m.

6. The machining tool as claimed in claim 1, wherein the pores of the porous structure are arranged in a honeycomb structure.

7. The machining tool as claimed in claim 1, wherein the pores of the porous structure are arranged in a bionic, random structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the invention are described hereafter in greater detail based on the figures, each of which shows a partly schematic illustration:

(2) FIG. 1 shows a side view of a machining tool designed as a modular carrier tool;

(3) FIG. 2 shows a sectional view through the machining tool as shown in FIG. 1 along intersecting line A-A;

(4) FIG. 3 shows a sectional view through the machining tool as shown in FIG. 1 along intersecting line C-C;

(5) FIG. 4 shows a sectional view through the machining tool along intersecting line B-B;

(6) FIG. 5 shows a sectional illustration of a grid-shaped core structure;

(7) FIG. 6 shows an enlarged illustration of the area of the tool tip demarcated by a circle E in FIG. 1;

(8) FIG. 7 shows a perspective illustration of a machining tool;

(9) FIG. 8 shows an enlarged illustration of the area of the tool tip identified with a circle D in FIG. 7;

(10) FIG. 9 shows a side view of a further machining tool; and

(11) FIG. 10 shows a sectional view of the machining tool according to FIG. 9 along the intersecting line F-F.

(12) Parts having the same effect are given the same reference numbers in the figures.

DETAILED DESCRIPTION OF THE INVENTION

(13) The machining tool 2 illustrated in FIG. 1 is designed as a modular drill tool. It has a tool tip 4 in the form of a cutting element made of solid carbide or ceramic, which is reversibly and replaceably attached to the frontal end of a base body 6. In the present invention, a tool tip is generally understood to mean the frontal end area of the machining tool 2, i.e. a front end face area of the machining tool. In the exemplary embodiment according to FIG. 1, this is formed by the replaceable tool tip 4. In the case of a carrier tool having plate seats for attaching (indexable) inserts as cutting element, the area of the plate seat is understood to mean the tool tip. In a non-modular, one-piece tool, a front end area having an axial length, for example, in the range of a nominal diameter of the machining tool 2 is referred to as the tool tip. In the exemplary embodiment according to FIG. 1, the tool tip 4 is clamped as a reversibly replaceable insert between two clamping or retaining webs 7 of the base body 6.

(14) The machining tool 2, and thus also the base body 6, as well as the tool tip 4 each extend in an axial direction 10 along a center axis 8 from a rearward end to a front end. At the same time, this center axis 8 defines a rotational axis around which the machining tool rotates in a rotational direction D during operation.

(15) The base body 6 is in turn divided into a rear shaft part 12, with which the machining tool 2 is held clamped in a tensioning piece of a machine tool during operation. A cutting part 16 provided with chip flutes 14 adjoins the shaft part 12 in the axial direction 10. In the exemplary embodiment, the chip flutes 14 extend in a helical pattern. The end-face tool tip 4 has major cutting edges 18, each of which typically transitions into a minor cutting edge 20 on the circumferential side. These are continued in the cutting part 16.

(16) A support bevel 24 adjoins the minor cutting edge 20 opposite the direction of rotation.

(17) As is described below based on FIGS. 2 through 5, the base body 6 is a monolithic base body 6, which is formed not from a solid material, but ratherat least in axial sectionshas a non-solid core structure 26. As FIG. 2 in particular illustrates, this core structure is designed as a circular structure in the shaft part 12, as seen in the cross-sectional view. The core structure 26 in this shaft part 12 is preferably designed to have a constant radius R.sub.1. It preferably extends at least nearly over the entire length of the shaft part 12 in the manner of a cylinder. This cylindrical core structure 26 is surrounded by an outer jacket 28, which, except for a flattening 30 introduced externally, is designed as an annular ring. The outer jacket 28 has a radius R.sub.2. The radius R.sub.1 of the core structure 26 is preferably around 50 to 90% of the outer radius R.sub.2. The core structure 26 has a core cross-sectional area A1, and the machining tool 2 has a total cross-sectional area A2. This area is defined by the area enclosed by the outer jacket 28, including the surface of the outer jacket 28.

(18) At the rearward end of the shaft part 12, the same is optionally closed off with an end face plate formed of a solid material, i.e. the non-solid core structure 26 is formed only in the interior of the shaft part 12, without being visible from the rearward end face. A coolant transfer point is expediently formed and incorporated in this solid end face plate. In particular, a transverse groove having through-holes running to the core structure 26 is introduced.

(19) In the exemplary embodiment, the core structure 26 is limited, in a similar manner, also in axial direction 10 in the end area of the shaft part 12 by a solid partition 32 through which at least one, or in the exemplary example two, cut-outs 34 penetrate. Alternatively, the core structure 26 also spans from the shaft part 12 into the cutting part 6 uninterrupted and without partition 32. A partition 32 is provided particularly in machining tools 2 without internal coolant supply. However, coolant supply is, in principle, made possible via the cut-outs 34 in the cutting part 16.

(20) In the front area of the machining tool 2, i.e. in the area of the tool tip 4, at least one outlet point 35 for coolant or lubricant is provided. Multiple outlet points 35, which are oriented for example toward cutting areas, are preferably formed in a front end face or are also formed circumferentially. The outlet point 35 can be designed in a conventional manner as a borehole. However, it is likewise preferably created by means of the 3D printing method and is geometrically complex. The core structure 26 is preferably led to the outside to form the outlet point 35. In the exemplary embodiment illustrated in FIG. 1, an outlet point 35 is formed, for example, in a circumferential wall 36 in the area of the tool tip and particularly as a porous structure. The outlet point 35 in the exemplary embodiment is thus generally integrated into the retaining webs 7.

(21) The core structure 26 continues into the cutting part 16 itself (FIG. 4). Owing to the chip flutes 14 and the thereby modified circumferential geometry of the base body 6, the cross-sectional geometry of the core structure 26 is adapted in particular such that it is enveloped entirely by roughly the same wall thickness of the outer jacket 28. In particular, the core structure 26 is designed to be elongated in the cutting part 16 and has a center area 37, which transitions into widened areas 38 at both ends. The outer edge of each said widened area has an arcuate contour, so that the widened area run concentrically to the circumferential line of the base body 6.

(22) The core structure 26 is preferably homogeneous and even over its entire cross sectional area A1. Alternatively, additional supports can be provided in a manner not further illustrated here. Separate coolant channels are expediently not formed in the embodiment variants of FIG. 1.

(23) According to a first embodiment variant, the core structure 26 is designed as a porous structure. According to a second embodiment variant illustrated in FIG. 5, the core structure 26, is, in contrast, designed as a grid-like, in particular honeycomb-shaped, structure. This structure has a plurality of individual channels 40 extending in the axial direction 10. Rectangular channels are schematically illustrated in FIG. 5. The individual channels 40 are each separated from one another by dividing walls 42. These dividing walls 42 preferably have only a low material thickness of, for example, below 0.3 and, particularly, below 0.15 mm. The individual channels 40 have a channel width W of usually below 0.5 mm.

(24) The base body 6 is manufactured using what is referred to as a 3D printing method. In this method, a metal powder is worked successively and thus layer-by-layer by means of laser treatment according to the desired cross-sectional geometry of each layer and melted or sintered to form a cohesive, monolithic sub-body. In this process, each cross-sectional contour of each layer is predefined by the laser. With this 3D printing method, nearly any arbitrary as well as complex and, in particular, variable cross-sectional geometries can be realized. In particular, the core structure 26 described for FIGS. 2 through 5 and having the solid enveloping outer jacket 28 is realized using this method. The entire base body 6 is thus realized as a one-piece, monolithic body by means of this manufacturing method. This body can also undergo finishing work following the 3D printing process.

(25) The base body 6 is preferably made of a tool steel according to DIN EN 10027, for example with a material number 1.2709 and/or 1.2344.

(26) As is apparent in particular from FIG. 6 in conjunction with FIG. 1, the machining tool 2 in the area of the tool tip 4 has a cooling structure 4 which, in the embodiment variant according to FIG. 6, is designed as a planar, porous structure 50. This structure is led from inside to outside and forms the outlet point 35 in the circumferential wall 36 forming a drill back. This circumferential wall 36 thus forms an outer cladding. As FIG. 6 shows, the outlet point 35 extends over a large portion of the circumferential wall 36 and is planar. Viewed in the circumferential direction, the outlet point 35 thus extends for example over 40 to 80% of the available area between the minor cutting edge 20 and the succeeding chip flute 14. The circumferential wall 36 extends in the circumferential direction between these two elements. The porous structure 50 and thus the outlet point 35 also extend in the axial direction 10 over a large axial length of the circumferential wall 36, for example in turn over an axial length which corresponds to 0.25 to 4 times the nominal diameter of the machining tool 2.

(27) Alternatively or additionally, a porous structure of this type having an outlet point 35 is also formed in the area of a chip flute wall 56 of the chip flute 14, as is illustrated in FIGS. 7 and 8. In this case as well, the outlet point 35 has a large-surface-area design. It extends preferably over 10 to 100% of the axial length of the tool tip 4 or is, for example, between 30 and 100% of the nominal diameter of the machining tool 2. If needed, the porous structure 50 can also be formed in the base body 6 in the chip flute wall 56 or on the circumferential wall 36. It is also apparent particularly from FIG. 8 that the outlet point 5 extends within the chip flute 14 over a comparatively large arc segment of the chip flute 14 and covers, for example, between 10 and 60% of the chip flute wall 56 in the circumferential direction of the chip flute 14. In the exemplary embodiment, the outlet point 35 is formed at the end of the chip flute 14 opposite the minor cutting edge 20, preferably in the retaining web 7.

(28) Like in the exemplary embodiment shown in FIG. 1, in the exemplary embodiment shown in FIG. 7 the base body 6 has two opposite retaining webs 7 designed as clamping webs between which the tool tip 4 is clamped as cutting insert. The tool tip 4 is reversibly replaceable and is preferably held between the two retaining webs 57 solely by way of a clamping force. The cooling structure is generally integrated in particular in these retaining webs 7, and the at least one outlet point 35 is formed on these retaining webs 7.

(29) Finally, FIG. 8 shows an additional third outlet point 35 in an end face 58, which allows coolant to exit immediately in the area near the major cutting edges. As FIG. 7, for example, shows, this end face 58 is slightly recessed compared to the tool tip 4 that is employed. In the exemplary embodiment, this end face 58 is formed in the lateral retaining webs 7.

(30) The porous structure 50 is connected in particular to the porous core structure 26 via which it is supplied with coolant/lubricant during operation. The two structures 50, 26 expediently differ in terms of, for example, their porosity or also in terms of pore size, etc. Within the core structure 26, variation can also be provided by having different structures in the shaft area and in the cutting area.

(31) FIGS. 9 and 10 finally illustrate a further exemplary embodiment in which, instead of the porous structure 50 as the cooling structure in the tool tip, multiple cooling channels 60 are formed, which are bent in the shape of a U in the area of the tool tip 4 and comprise a reversing segment 62. The cooling channel 60 thus comprises two channel segments 60a, 60b that run virtually antiparallel to one another. In the exemplary embodiment, the one channel segment 60 ends at a channel outlet 64 which is directed away from the front end of the machining tool 2. The other channel segment 60a is routed in the base body 6 to a coolant interface up to a rear end in the area of the shaft part 12, and in particular in a straight line or parallel or coaxial in relation to the center axis 8. The reversing segment 62 is in turn integrated into the respective retaining web 7. In the exemplary embodiments shown, conventional further cooling channels 66 are additionally provided (FIG. 9), which run in a helical pattern in the base body 6 and exit at the end face 58 or in the chip flute 14, for example.

(32) The channel outlet 64 is preferably directed at a cutting element not illustrated in greater detail here. The cutting element is in particular a replaceable cutting plate. During operation, the coolant exiting the channel outlet 64 thus deliberately reaches the cutting element. Elongating an imaginary longitudinal axis of the channel segment 60b in front of the channel outlet 64 thus intersects in particular the edge of the cutting element.

(33) As an alternative to this embodiment variant having the channel outlet 64, it is also possible to form a closed cooling circuit. For this purpose, the second channel segment 60b would then also be routed back to the rear coolant interface at the end portion of the shaft part 12. In this embodiment variant as well, the cooling channels 60 are designed with the reversing segment 62 in the respective clamping web of the base body 6.