DE102008052743A1 - Tool i.e. twist drill, for machining workpiece, has regions provided along axial extension of tool, geometrically defined cutting edge and center axis, where regions are alternately made of ductile and hard materials - Google Patents

Abstract

The tool (1) has regions (7, 9, 11, 13) provided along an axial extension of the tool, a geometrically defined cutting edge (15) and a center axis (M). The regions are alternately made of ductile and hard materials. Another cutting edge is formed in an area of a radial step along the axial extension, and in the hard material. The hard material encompasses viscous material. A coolant- or lubricant channel penetrates the tool along the extension. The hard material includes polycrystalline diamond, polycrystalline boron nitride and/or chemical vapor deposition diamond.

Description

The The invention relates to a tool for machining workpieces according to the preamble of claim 1.

Tools of the type mentioned are known. Such tools are common necessary to shape the cutting edges of a hard material. Especially then, if - as for example with drills - the Cutting arranged on an end face of the tool results The problem is that you are looking for a tool with a larger diameter much more needed from the hard material than for a tool with a smaller diameter. Because hard materials are very are expensive, it is desirable to use the amount to a minimum, without losing the properties of Tool to affect.

From the international patent application WO 93/02823 For example, a drill is known that has a layer of a hard material over a body of tough material. The cutting edges are completely formed in the hard material. Depending on the desired tip angle, the layer thickness of the hard material must be adjusted so that the cutting edges can be formed along their entire extent in this. It is obvious that the layer thickness of the hard material has to be larger, the smaller the point angle should be. Furthermore, it can readily be seen that the layer thickness of the hard material at a given point angle is a function of the tool diameter. In particular, with small point angles and large tool diameters one needs a comparatively large amount of the hard material.

Also from the WO 93/02823 is a tool, in particular a drill, known, the - seen along a direction perpendicular to a central axis of the tool - has a layer structure, wherein three layers are present, of which the outer two have tough material, while the inner hard material having. In the front side of such a tool cutting can be introduced, which are preferably formed completely in the hard material. If the diameter of the tool is increased, the required amount of hard material does not increase in the same way as if a complete frontal area of the tool were formed entirely of hard material. A disadvantage of such an embodiment is that, for example, in a drill due to the limited thickness of the inner layer of the spiral angle for the flutes can be selected only in a narrow range, if they should extend at least in one of the cutting edge facing area in the hard material. It is therefore desirable to find another solution which, on the one hand, makes it possible to reduce the amount of hard material used but, on the other hand, does not limit the quality of the tool nor is it subject to any restrictions on, for example, the spiral angle of the flutes.

at Tools with frontally arranged cutting it is common known to be due at constant angular velocity radially increasing from inside to outside web speed of the rotating tool at a given feed only an outer one Field of cutting does real cutting work while the slower rotating inner part rather pushes. On the Basis of this realization is possible, a tool so that only the outer part of the Cutting that does real cutting work, made in hard material is while his inner part essentially pushing formed in tough material.

task The invention is therefore the knowledge just described to use, to create a tool in which almost any diameter can be realized while at the same time a minimum of hard material is used, with no restrictions whatsoever For example, occur with respect to the spiral angle of the flutes.

The Task is solved by a tool with the features of the claim 1. The tool is characterized in that it has at least three areas along its axial extent, wherein at least three adjacent areas alternately tough and hard material. Unlike the ones in the prior art On the one hand, more than two areas are provided for known tools. which include different materials. On the other hand, the different ones Areas not arranged along a direction perpendicular is on a central axis of the tool, but the areas are arranged along the axial extent of the tool. there At least three areas are foreseen, of which at least three adjacent areas each alternating hard or Tough material include. Preferably, there is a layer structure when a layer of hard material between two layers made of tough material.

A particularly preferred tool is characterized in that at least part of the at least one geometrically defined cutting edge is formed of hard material. For example, if the tool has the mentioned layer structure, a middle layer comprising hard material, is surrounded by two layers, each comprising tough material, the end face of the tool can be formed so that an outer part of the at least one geometrically defined cutting edge is formed of hard material, while an inner part is formed of tough material. Since in the machining of a workpiece on the inner part due to the lower cutting speed substantially compressive forces act, it is advantageous to form this range of tough material, which is more likely to absorb these compressive forces, as the brittle, hard material. In the outer area, however, where high cutting speeds prevail, the cutting edge can be formed in hard material, so that here a high wear resistance is given.

Prefers is also a tool that is characterized in that at least an area that includes hard material, even tough material includes. Here is an area addressed, the only partially has hard material while it is tough in some areas Material has. For example, the area to the peripheral surface of the tool include hard material while a inner part of the region is formed of tough material. Preferably this area is spaced from the front of the tool, so that faces towards the front - along the axial extent seen - at least one other area connects.

In In this context, a tool is preferred in which in at least one area of both hard and tough Material includes, the hard material is the tough material in the form of a ring. In this case, there is an outer one Ring of the area of the hard material, while that - preferably cylindrically shaped - inside of this area of tough Material is formed.

It Also, a tool is preferred that has at least five areas each having at least three adjacent areas alternately tough and hard material. For example, here is a layer structure be provided, in which initially a middle layer, The hard material includes, between two layers, the tough material embrace while nestling on one of the two outer ones Layers another layer of hard material connects, which in turn is followed by a layer of tough material. In other words, in this case, there is a middle one Layer of tough material, attached to both sides each connect two layers, with the first each hard, and each second tough material includes. So there are also at least three adjacent areas here which alternately comprise tough and hard material.

Especially Also preferred is a tool extending through a radial step along its axial extent, being in the range of Stage formed at least one geometrically defined cutting edge is. Such a tool can be used, for example, to Insert counterbores in a workpiece.

In In this context, a tool is preferred, which is characterized is characterized in that in the area of the stage, an area is arranged, the hard material, wherein the at least one cutting edge at least partially ge in the hard material forms is. In this way the tool can also benefit from the advantages in the area of in connection with the layer structure or the different areas were explained.

It also a tool is preferred, which is characterized by at least one Coolant and / or lubricant channel is characterized, the Tool penetrated substantially along its axial extent. In this way it is possible to cool and / or To introduce lubricant into the region of the at least one cutting edge, and not just the tool and the workpiece efficiently to cool and lubricate, but also incurred in the processing Remove chips from the area of at least one cutting edge.

moreover also a tool is preferred, which is characterized by the hard material comprises PKD and / or PKB and / or CVD diamond. These materials are special because of their high hardness wear-resistant and suitable, one cutting edge in one area form, in which high cutting speeds occur. The Hard material may preferably also be made of the materials mentioned consist.

It also a tool is preferred, which is characterized by that the tough material includes carbide. Because of his significantly higher compared to the previously mentioned hard materials Tungsten carbide is above all for an area where lower cutting speeds and for that higher pressure forces occur. Preferably The tough material also made of carbide.

The The invention will be explained in more detail below with reference to the drawing explained. Show it:

1 a side view of an embodiment of the tool, which is exemplified here as a drill;

2 a perspective view of the tool 1 , and

3 a side view of another embodiment of the tool, which is exemplified as a stepped drill.

1 shows a first embodiment of a tool 1 , which is exemplified as a drill. The tool 1 has a central axis M, which is indicated in the left portion of the figure. It also has a first part 3 on, which is designed here as a shaft and the coupling is used with a machine tool. In addition, it includes a second part 5 , which is suitable for the actual machining of a workpiece.

The tool 1 is at least in the second part 5 along its axial extent divided into several areas. At its end facing a workpiece, it initially has a first area 7 on, which is a second area 9 followed. In turn, this is followed by a third area 11 at. Depending on the configuration or length of the tool, further areas may be adjacent to the third area 11 in particular a fourth area 13 can be seen.

At least three adjacent areas of the tool 1 alternately have tough and hard material. For example, the first area 7 Tough material include while the second area 9 includes hard material. The third area 11 may again comprise tough material. The tough material may comprise hard metal, preferably it may be made of hard metal. The hard material may comprise PCD and / or PKB and / or CVD diamond, preferably consist of these materials or of one of these materials.

The areas 7 . 9 . 11 may optionally each consist of hard or tough material. One area may also include one type of material, while another area may consist entirely of one type of material.

Is a fourth area 13 provided, which is connected to a third area 11 joins, so can this fourth area 13 be formed of the same material as the third area 11 , Accordingly, in the present embodiment, the fourth region is made of tough material. A fourth area 13 can then be provided when the tool 1 should have a certain length. The different areas 7 . 9 . 11 . 13 Namely, they can be formed by sintering, with an upper limit for the length of the sintered material. Should the tool 1 Thus, having a length exceeding this predetermined by the sintering process length, several individually sintered areas must be arranged one behind the other and connected to each other in a suitable manner. The individually sintered and successively arranged areas can for example be soldered or glued together. So it is important that the third area 11 not necessarily a fourth area 13 must connect. Conversely, the fourth area can be 13 quite an arbitrary number of other areas connect, if the tool should have a corresponding length. For example, the first part 3 of the tool 1 likewise formed of a sintered material, different areas may adjoin one another here as well, which could be characterized by vertical lines. It is therefore to be noted that on the one hand the vertical line, the third area 11 from the fourth area 13 separates, may be omitted, while conversely further vertical lines, especially in the first part 3 of the tool 1 depending on its design can occur.

In the production of the tool 1 is it possible, for example, the areas 7 . 9 and 11 in a common sintering process, this sintered product subsequently having a fourth region 13 connected in a suitable manner, for example, soldered or glued. On the other hand, it is also possible, the individual areas 7 . 9 and 11 individually, and then in a second step in a suitable manner - for example, by soldering or gluing - optionally with other areas to a tool 1 get connected.

2 shows a perspective view of the embodiment of a tool 1 according to 1 , The same and functionally identical elements are provided with the same reference numerals, so reference is made in this regard to the preceding description. The tool 1 has at least one geometrically defined cutting edge 15 on, on one end face 17 of the tool 1 is formed. In the present embodiment, the tool 1 two geometrically defined cutting edges 15 on, of which only one is recognizable here. In an outer peripheral surface 19 of the tool 1 are two flutes 21 . 23 introduced, which are exemplary spirally formed here. The flutes can also run straight or along another curve. In each case one of the frontal boundary edges of the flutes 21 and 23 forms the geometrically defined cutting edges 15 , In an embodiment in which only one geometrically defined cutting edge 15 is provided, if necessary, only a flute 21 in the outer peripheral surface 19 of the tool 1 brought in. Conversely, in one embodiment, the multiple geometrically defined cutting 15 has, just as many flutes 21 . 23 in the peripheral area 19 be introduced, such as cutting 15 available. However, chip flutes can be completely dispensed with become.

In the in 2 illustrated embodiment, the cutting edge runs 15 both in the first area 7 as well as in the second area 9 , Part of the cutting edge 15 is thus made of hard material, while another part is made of tough material. The closer to the peripheral surface 19 lying part of the cutting edge 15 is in the second area 9 designed so that it includes hard material. In this part of the cutting edge, a higher cutting speed occurs when machining a workpiece, so that the cutting edge 15 must have substantially wear-resistant properties. It is therefore advantageous that the cutting edge 15 just in this part includes hard material. A closer to the central axis M arranged part of the cutting edge 15 is in the first area 7 formed so that this part comprises tough material. Here, a lower cutting speed occurs during the machining of a workpiece, so that this part of the cutting edge pushes rather than cuts. Therefore, it is advantageous if this part of the cutting edge 15 a material that can absorb high pressure forces. Preferably, therefore, this part is formed in tough material.

The second area 9 can be made entirely of hard material. It is certainly possible, the second area 9 such that it, for example, in one of the peripheral surface 19 facing part comprises hard material, while arranged in the region of the central axis M core of this area 9 includes tough material. Such a design has particular tools 1 with large diameter the advantage that hard material can be saved. In this case, the second area 9 designed so that it includes both hard material and tough material. In a particularly preferred manner, the hard material can embrace the tough material in the form of a ring. The second area 9 In this case, it consists of an outer ring comprising hard material, while concentrically arranged in this outer ring is an inner cylinder comprising tough material. Even in such an embodiment, it is possible to use the cutting edge 15 to be arranged so that it is at least partially made of hard material. As the area 9 has an outer ring of hard material is then an outer part of the cutting edge 15 made of hard material, so a part on which high cutting speeds occur.

Of course it is also possible, the cutting edge 15 completely in an area that includes hard or tough material. However, particularly preferred is a cutting edge, which has both hard and tough material. In particular, a cutting edge 15 preferred in which an inner part of tough material is formed, while an outer part is formed in hard material.

In an embodiment in which the individual areas 7 . 9 and 11 each consist of tough or hard material, they are discreetly separated from each other. The area boundaries are therefore formed by places where discontinuities in the physical properties of the material covered by the areas occur. In an embodiment in which, for example, the second area 9 includes an outer ring of hard material and an inner ring of tough material, such a discrete demarcation is only partially given. Through the second area 9 extends a core of tough material, the quasi the areas 7 and 11 in terms of toughness as a physical property. In this respect, there is no discontinuity in the physical properties at least in the vicinity of the central axis M, at least if no soldering, adhesive or other connection points are present. Nevertheless, the different areas can be clearly distinguished from each other. For example, the physical properties of the material in the region of the peripheral surface 19 of the tool 1 use for differentiation. Namely, if one exceeds the peripheral surface 19 along the axial extent of the tool, the area boundaries between the areas 7 . 9 and 11 Also, in this embodiment, one will notice a discontinuous change in the physical properties of the material encompassed by the different regions. Limits two areas of the same material to each other, such as the third area 11 and the fourth area 13 , there is a connection at this point, which also leads to a discontinuity in the physical properties. Here, for example, a soldering or splice may be arranged. This implies, at the very least, that there is another material at this point, which causes the two areas to connect with each other. In this respect, it is also possible to speak of a physical discontinuity, so that this concept is suitable for defining the domain concept.

At the front 17 of the tool 1 are openings 25 recognizable, in which opens at least one coolant and / or lubricant channel. Preferably, each opening 25 associated with a coolant and / or lubricant channel. Of course, only one opening 25 be provided with a coolant and / or lubricant channel, but it can also have multiple openings 25 be provided, in which optionally one or more - preferably an equal number - open cooling and / or lubricant channels.

The at least one cooling and / or Lubricant channel penetrates the tool 1 essentially along its axial extent. It serves to cool and / or lubricant from the machine tool through the tool 1 to the front side 17 to lead, where it directly the machined area of a workpiece as well as the tool 1 can cool and lubricate. At the same time, the coolant and / or lubricant serves to discharge the chips produced during the machining of the workpiece from the cutting area. This is especially true when the coolant and / or lubricant is supplied under high pressure.

3 shows a further embodiment of a tool 1 , which is designed as a stepped drill. The same and functionally identical elements are provided with the same reference numerals, so far reference is made to the previous description. To the fourth area 13 closes here a fifth area 27 to which in turn a sixth area 29 followed. In this case, the fifth region preferably comprises 27 hard material, while the sixth area 29 includes tough material. Depending on the length of the tool, instead of the two areas 11 . 13 both comprising tough material, a single area comprising tough material may be provided. In this case, the area is 27 a fourth area while the area 29 represents a fifth area. The tool then has five areas along its axial extent, with at least three adjacent areas alternately comprising tough and hard material. In the illustrated embodiment, the areas include 7 and 11 tough material, while the interposed area 9 includes hard material. Furthermore, the areas include 13 and 29 tough material while the area 27 includes hard material. Even if instead of the separate areas 11 and 13 a single region comprising tough material would be provided, each three adjacent ones of the five regions formed in this case would alternately comprise tough and hard material. So that would be the area 7 Tough material, the area 9 hard material and the subsequent middle area again include tough material. Here, the count would have to start anew so that for the second adjacent three areas, this middle area comprising tough material would be the first area to which the area adjoins 27 connects, which includes hard material, in turn, a third area 29 follows, which includes tough material. As already explained, it depends only on the desired length of the tool 1 from, whether between the areas 9 and 27 one area, two areas 11 and 13 or even several areas are provided which comprise tough material.

Preferably, at the workpiece facing the end of the tool 1 an area provided which comprises tough material. Likewise, it is preferably at the end of the tool 1 , which faces a machine tool, also provided with tough material. This arrangement requires that in the event that always alternate along the axial extent of the tool areas hard and tough material with each other, an odd number of areas is realized. An even number of areas is thus achieved when along the axial extent of the tool 1 Adjacent areas that comprise the same material. As in the embodiment that is made 3 indicates the third area 11 and the fourth area 13 are each formed of tough material, this results in a total of six areas along the axial extent of the tool 1 , Would be instead of the two areas 11 and 13 a single area of tough material would provide five areas. This consideration does not take into account that possibly the first part 3 of the tool 1 , which forms a shaft for receiving it in a machine tool, can be formed from a plurality of regions, because its length exceeds the length which can be produced during a sintering process. In this case, of course, results in a larger number of areas.

In the tool 1 can be formed along its axial extent a radial step. Preferably, a geometrically defined cutting edge is formed in the region of the step. In the present embodiment, in the fifth area 27 a step 31 educated. In the area of this stage is a throat 33 in the outer peripheral surface 19 of the tool 1 brought in. A boundary line of this throat 33 forms a geometric cutting edge 35 while the inside of the throat 33 serves as chip space. The cutting edge 35 is relative to the cutting edge 15 offset radially outwards and serves to increase, for example, a bore introduced into a workpiece in its upper region. Instead of a cutting edge 35 can along the circumference of the tool 1 also two or more cutting edges, preferably formed by corresponding grooves, in the region of the step 31 be provided.

The cutting edge 35 Here is completely in the hard material of the area 27 educated. It is also possible the stage 31 to arrange at a transition between two areas, one of which comprises a hard and the other tough material. That way, the throat can 33 and also the cutting edge 35 Hard and tough material, wherein it also here preferably in its outer region of hard material and in its inner region of tough material. Since the cutting speed in the outwardly projecting peripheral portion of the step 31 or the cutting edge 35 compared to the cutting speed of the cutting edge 15 is higher, will be the cutting edge 35 however, preferably formed entirely in hard material.

Is the diameter of the tool 1 especially in the area of the stage 31 very big, it can be beneficial to the area 27 not completely made of hard material. Instead, the area can be 27 Both hard material and tough material include. Preferably, it comprises in the part that the outer peripheral surface 19 of the tool 1 facing hard material, while in a central axis M facing part comprises tough material. Particularly preferred would be an embodiment in which also in the field 27 the hard material surrounds the tough material in the form of a ring. In the region of the circumference therefore a ring of hard material is formed, which concentrically surrounds a cylinder of tough material. Even in such an embodiment, it is possible to use the stage 31 or the throat 33 and preferably the cutting edge 35 completely in hard material form. Preferably, the various parts or regions can also be sintered together here or, after the sintering of the individual parts or regions, connected to one another in a suitable manner, for example, soldered or glued.

Of course, it is also possible in the area of at least one cutting edge 35 provide at least one opening for coolant and / or lubricant, which is fed by at least one cooling and / or lubricant channel.

After all, it turns out that the present invention advantageously makes use of the knowledge that - seen in the radial direction - different areas of a tool 1 have different cutting speeds and therefore subject to different stresses. It is therefore possible to form these regions from different materials. For this purpose, an arrangement of different areas along the axial extent of the tool offers, with parts of tough and hard material alternating with each other. So it is possible to produce tools with a large diameter, without the need for an uneconomically large amount of expensive hard Ma terials should be used. At the same time, there is no compromise on the quality of the tool 1 To be received. Also, there are no restrictions on a helix angle of any flutes present in the tool. According to the invention, it is also possible to provide step tools in which in each case only the regions comprise hard material in which a high cutting speed occurs.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• WO 93/02823 [0003, 0004]

Claims (12)

Tool for machining workpieces with at least one geometrically defined cutting edge ( 15 ) and with a central axis (M), characterized in that the tool along its axial extent at least three areas ( 7 . 9 . 11 ; 13 . 27 . 29 ), at least three adjacent areas ( 7 . 9 . 11 ; 13 . 27 . 29 ) alternately comprise tough and hard material. Tool according to claim 1, characterized in that at least a part of the at least one geometrically defined cutting edge ( 15 ) is formed of hard material. Tool according to one of the preceding claims, characterized in that the regions ( 7 . 9 . 11 ; 13 . 27 . 29 ) each consist of hard or tough material. Tool according to one of claims 1 or 2, characterized in that at least one area ( 9 . 27 ), which includes hard material, also includes tough material. Tool according to claim 4, characterized in that in at least one area ( 9 . 27 ), which includes both hard and tough material, the hard material surrounds the tough material in the form of a ring. Tool according to one of the preceding claims, characterized in that the individual areas ( 7 . 9 . 11 . 13 . 27 . 29 ) are discreetly separated from each other. Tool according to one of the preceding claims, characterized in that the tool ( 1 ) along its axial extent at least five areas ( 7 . 9 . 11 . 13 . 27 . 29 ), wherein in each case at least three adjacent areas ( 7 . 9 . 11 ; 13 . 27 . 29 ) alternately comprise tough and hard material. Tool according to one of the preceding claims, characterized by a radial step ( 31 ) along the axial extent, wherein in the region of the step ( 31 ) at least one geometrically defined cutting edge ( 35 ) is trained. Tool according to claim 8, characterized in that in the area of the step ( 31 ) an area ( 27 ), which comprises hard material, wherein the at least one cutting edge ( 35 ) is at least partially formed in the hard material. Tool according to one of the preceding claims, characterized in that the hard material PKD and / or PKB and / or CVD diamond, preferably of PCD and / or PKB and / or CVD diamond exists. Tool according to one of the preceding claims, characterized in that the tough material is carbide comprises, preferably consists of hard metal. Tool according to one of the preceding claims, characterized by at least one coolant and / or lubricant channel, the tool substantially along its axial extent interspersed.