MXPA97007414A - Co tool - Google Patents

Abstract

The present invention relates to a cutting tool, especially a drill, a milling cutter, a threaded nut, a scalar machine and a drill string, comprising an axis and a cutting member (2) in which at least one cutting edge (8, 9, 28) for machining a workpiece (30), wherein said cutting member is covered with a sliding layer (20) having a hardness lower than that of the base layer (26) or a base body (20) of said cutting member, and wherein in an open space (10) of the cutting tool (2) a plurality of recesses similar to grooves (14) and / or in a groove ( 4, 5) in the area of said cutting edge (8, 9) in at least one slot (1

Description

CUTTING TOOL Field of the Invention The invention relates to a cutting tool such as a drill, a milling cutter, a threaded nut, a scanning machine or a drill string according to the preamble of claim 1. BACKGROUND OF THE INVENTION The use of numerical control machine tools has been a substantial contribution to increase productivity, flexibility, processing quality and efficiency of modern production devices. The versatile possibilities of information control and processing techniques have been responsible for the design of machines suitable for use in automatic processing systems. Systems of this type are usually equipped with tools and means of storing the parts being worked, automatic changeover means and integrated measuring stations in order to -simplify the manual stages "that take the machine operator. The sensors to monitor the states of the functions and the process of the machine, such as use and breakage of the tools, ensure the sequence of automatic elaboration. In order to be able to exploit the total capacity of such machine tools, in parallel with the development of machine tools, appropriate tools have also to be provided that allow a prolonged life of the tool as well as an increase in the cutting speed, in such a way that processing times can be minimized. However, in the case of modern machining processes, the increase in cutting speed does not necessarily need to be of greater importance, but rather with particular applications, such as, for example, the machining of light metals, which may endeavor to be distributed with refrigerants and lubricants or at least to reduce the use thereof and, on the other hand accept a reduced cutting speed. In the case of tools having geometrically defined cutting edges, such as, for example, drills, milling cutters, scanning machines, screw taps, drill trains, etc., tool steels are preferably used as cutting materials. of high alloy, hard metals, ie sintered materials of hard metallic materials such as, for example, cerametal, ceramic inserts, monocrystalline diamond, polycrystalline diamond, polycrystalline boron nitride, etc. Furthermore, there are known tools in which the resistance to the use of the tools is further increased by covering them with layers of hard material, such as, for example, titanium nitride, titanium carbide and aluminum oxide. DE-OS 23 57 134 discloses a cutting tool in which a precious metal coating film is applied by an ionic sedimentation method. DE-AS 12 71 495 relates to a method of manufacturing a cutting tool in which a coating layer of copper or brass is applied to the portions that are not going to harden prior to a hardening operation. The known cutting tools of the two aforementioned publications have the common drawbacks that, on the one hand, the coating layers consist of comparatively expensive materials and the tool life is improved, especially when processing light metals. The continuous development of machine tools and the use of novel methods, such as dry machining, for example, where the pieces to be machined without using refrigerants / lubricants, or machining with reduced quantities of refrigerant, and the effort to obtain times of increasingly reduced manufacturing makes that the requirements for the tools, in regard to the duration of the tool and the maximum cutting speed obtainable, can not be fully met by conventional tools. SUMMARY OF THE INVENTION The fundamental objective of the invention is to provide a cutting tool that has a simple design and allows an improved tool life while at the same time, the cutting speed is increased or the amount of refrigerant is reduced. This object is achieved by the features of claim 1. The deterioration of the tool can be considerably reduced by the application of a smooth sliding layer containing sulphides, selenides, tellurides, such as, for example, MoS2, bS2, TaS2, WS2. , MoSe2, NbSe2, TaSe2, WSe2, MoTe2, Te2, WTe2 or mixed compounds, to the cutting tool already «that small clipping fragments slide into the smooth sliding layer and thus the deterioration of the face is reduced and prevents clipping fragments from accumulating on the tool edge. In addition, the friction between the tool and the open face is minimized such that the wear of the open face is also reduced. In this way, the duration of the tool can be considerably improved by the sliding layer according to the invention compared with conventional solutions. Some coating methods are already known to apply anti-wear coatings to cutting tools, so that the respective description is presumed. A method of co-applicant VILAB AG / Switzerland has been implemented which is particularly suitable. It is particularly advantageous to apply the smooth sliding layer to a wear resistant base layer, which, instead, has been applied to the base body of the cutting tool so that the latter is provided with two layers. In order to ensure an optimum machining operation, the smooth sliding layer does not apply in the area of the cutting edge. This is especially advantageous when the base body of the cutting tool is made of a material of HSS, hard metal, cerametal or ceramic and the wear-resistant layer consists of TiN, TiAlN, TiCN, diamond or the like. Depending on the application, it is preferred to apply the base coat in a thickness of 1-10 μ, while the hardness of the base coat should be between 2,000-10,000 HV and the slip coat should have a Mohs hardness of 1-2. The measure to form one or a plurality of grooves, especially in grooved form, in the groove that promotes the breaking of the fragments such that the formation of long flowing fragments is prevented, which interferes with the operation cycle, for example in automatic machine tools, and the removal of the fragments is prevented. With the short discontinuous fragments a high quality surface is guaranteed, while the fragments can be easily removed. In addition, in the case of wet machining, the groove facilitates the supply of coolants and lubricants to the cutting portion of the tool such that the stability of the tool is increased and, in addition, the removal of the fragments is facilitated. Preferably on the face a plurality of grooves are formed which extend along the groove at a parallel distance. Fragment formation and discharge thereof can be further improved by also providing open space similar to grooves extending away from the cutting edge. The supply of coolant and lubricant, too, can be improved by such recesses compared to the above-described embodiment. The fragmentation capacity and the machining times of such a tool are superior to those of conventional tools, even if the parts being worked are machined in a dry state or with reduced refrigerant supply. In the event that the cutting edge is formed at the front of the cutting member, such as, for example, in bores, cylindrical milling cutters, sounding trains, etc., the recesses are advantageously formed as segments of a circle or spiral. in the open face which is positioned approximately concentrically with respect to the axis of the cutting tool. The formation of fragments and the supply of coolant and lubricant can be further improved by the fact that a recess is associated with each groove such that the recess is practically arranged as an extension of a groove. In special cases of application it may be advantageous to form grooves or recesses only over a partial area of the groove and the open space, respectively. They have proven to be especially advantageous when the amplitude and depth of the grooves and / or recesses are between 0.02-2 mm, preferably 0.02-0.5 mm. Further advantageous developments of the invention are described in the subclaims. BRIEF DESCRIPTION OF THE DRAWINGS In the following, the preferred embodiments of the invention are explained in detail in the form of schematic drawings. Figure 1 is a view of the cutting member of a helical drill; Figure 2 is a diagrammatic view from above in a fragment of a drilling tool; Figure 3 is a three-dimensional sectional view of a cutting tool according to the invention; Figure 4 is a diagram is "chemistry to explain the formation of fragments in a cutting tool according to the invention, - Figure 5 is a diagram comparing a conventional cutting tool with a cutting tool according to the invention; and Figure 6 is a diagram comparing a conventional cutting tool with a cutting tool provided with a sliding layer. DETAILED DESCRIPTION OF PREFERRED MODALITIES Figure 1 shows the cutting member 2 of a spiral drill 1 having two spiral grooves 4, 5 extending along the cutting member 2 to the fragment 6 of the bore. Each major cutting edge 8, 9 is formed in a wedge which, on the one hand, is formed by an open face 10 and, on the other side, by a face 12 of the groove 5.

In addition, in the embodiment shown, the recesses are formed in the open face 10 as grooves 14 extending concentrically from the major cutting edge 8 (9) to the trailing edge 16 of the open face. In each groove 4, 5 a plurality of adjacent grooves 18 forms the axis which is placed approximately parallel to the axis of the groove 5 (4), that is, the grooves 18 also extend in a spiral form near the axis 20 of the drill 1. As for the additional details on the design of the slots 18 and the recesses 14, reference is made to Figures 2 and 5. However, as further indicated in Figure 1 by the dotted lines, the Drill 1 and especially the cutting member 2 is covered with a non-applied sliding layer 20, in the area of the major cutting edges 8, 9. The sliding layer 20 preferably comprises sulfides, selenides, tellurides, such as , for example, MoS2, NbS2, TaS2, WS2, MoSe2 NbSe2, TaSe2, WSe2, MoTe2, NbTe2, WTe2 or mixed compounds thereof. When such slip layer 20 was applied the areas of the fragment 6 indicated by the dotted lines were covered by a suitable material so that the larger cutting edges 8, 9 would be formed by a harder material. With regard to the additional details about the sliding layer 20, the following figures 3 and 6 refer to them. Figure 2 shows a schematic view from above on the fragment 6 of the bore 1, where only the faces of the fragment of the bore are shown, where the minor cutting edges of the bore that rotate out of the projection plane have been omitted . As can be seen from this view, the two open faces 10, which are confined to the view according to figure 2, where on the one hand by the larger cutting edges 8 and 9, and on the other hand by the rear edges 16, they are formed by the two grooves 4, 5. The radially outer confinement of the open faces 10 is effected by the smaller cutting edges 22 and the smaller open faces 24. The two larger cutting edges 8, 9 are connected by the edge of the cutting edge. chisel 26 • extending through shaft 27 of the bore. On each open side 10 the recesses 14 are incorporated, as already mentioned above, which are formed in the illustrated mode as segments of a circle or spiral concentric with respect to the axis 27 of the bore 1. Each of the circular lines shown in FIG. 2 represent the lower part of a recess 14. According to FIG. 2, in addition to the grooves 18 that extend approximately perpendicular to the plane of projection along the grooves 4, 5 are formed on the faces of the grooves 4, 5 (perpendicular to the projection plane). Both the grooves 18 and the recesses 14 have a roughly corrugated or U-shaped cross section so that the larger cutting edges 8, 9 are formed in wave form. The depth and amplitude of the grooves 18 and / or the recesses 14 is approximately between 0.01-2 mm, preferably 0.02-0.5 mm, depending on the individual case. The sliding layer 20 mentioned at the beginning, is not formed in the area of the larger cutting edges 8, 9 so that "only the areas between the dotted line in FIG. 2 and the rear edges 16 of the faces 10 are covered with the sliding layer 20. In special cases of the application it may also be advantageous to extend the sliding layer 20 to the cutting edges 8, 9. Due to the wave shape of the faces 12 of the grooves 4 , 5 and the open faces 10, the coolant / lubricant supply - if used - for the larger cutting edges 8, 9 is considerably improved so that the wear of the bore 1 can be substantially reduced or the quantity can also be reduced of refrigerant. In addition, the corrugated structure of the groove causes a rupture of the previous fragment so that - as already mentioned at the beginning - comparatively short discontinuous fragments are formed - which ensure a high quality of the surface and, at the same time they can be easily downloaded. The superiority of this "groove section" as it is called, compared to conventional earth sections is emphasized in Figure 5. This is a comparison of the tool life in two helical drill bits, one of which was provided with a flat open face and a planar or grooved face, while the comparison tool was provided with the grooved section according to the invention in the grooves 4, 5 and the open faces 10. A workpiece of 42CrMo4V was machined by both drills, where the two holes were not provided with the sliding layer 20 mentioned above. Both helical drill bits have geometrically identical dimensions - apart from the slot section - and were operated at the same cutting speed vc, the same feed f and the same cutting depth ap. As can be taken from FIG. 5, only by providing the grooved section, the tool life can be substantially improved compared to conventional tools so that the tool life and the maximum cutting speed obtainable from the tooling tools can be improved. according to the invention are superior to those of conventional tools especially in the case of dry machining or in the case of machining with a reduced amount of coolant / lubricant. Figure 3 represents a three-dimensional view of a drilling tool, where, for reasons of clarity, the grooves 18 in the grooves 4, 5 are indicated as dotted lines in the area of the larger cutting edges 8, 9. The recesses 14 on the open faces 10 are indicated only as dotted lines, because by means of figure 3 the cover of the bore 1 is illustrated. The base body of the bore can be made of conventional HSS steel for example, where either the full bore or, as indicated in Figure 3, only the cutting member 2, is provided with a hard base layer 26. This base layer 26 may consist, for example, of a hard ceramic material such as TiN, TiAIN, TiCN or diamond etc. As already mentioned at the beginning, the method of covering with PVD will not be discussed here, to simplify the matter, but reference is made to the relevant literature and, in particular, to the respective patent application of VILAB.

The base layer 26 extends to the larger cutting edges 8, 9 where in figure 3 the scratch indicative of the base layer 26 is not effected in the area of the larger cutting edges 8, 9. On the base layer 26 the aforementioned sliding layer 20 is formed which is indicated by a gray shading in figure 3. This sliding layer 20 is preferably prepared in the base of sulfide, selenide or telluride and thus has certain lubricating characteristics "which are will explain in more detail in the following. The sliding layer 20 does not extend over the entire cutting member 2, but terminates at a distance from the cutting edges 8, 9 so that the latter are formed by the hard wear-resistant base layer 26. That is, the The actual cutting area of the drill 1 is covered by the hard base layer 26, which may have, for example, the Vickers pyramid hardness of approximately 2,000 - 10,000 HV, while the other areas of the cutting member 2, which do not contribute directly to the machining operation, are covered with the comparatively smooth sliding layer 20 which may have, for example, a Mohs hardness of 1-2. In particular cases, the sliding layer 20 can also be applied directly to the base body so that it forms the base layer.

In order to illustrate the effect of this sliding layer 20, Figure 4 shows a sectional view of the cutting edge 28 of a cutting tool during the machining operation. A fragment 32 is removed from the workpiece 30 by the feeding movement in the direction of the arrow, the cutting edge 28 being formed by the hard and wear resistant base layer 26 in the area where the actual machining is performed. the workpiece 30. The fragment is removed along the face 12 and thus moves on the sliding layer 20 indicated as dotted lines which supports the sliding of the fragment along the face 12 due to its sliding effect (MoS2 ...). In this way the removal of the fragments from the actual machining area is supported so that, on the one hand, the fragment and thus the thermal energy can be quickly discharged from the workpiece and, on the other hand, the wear of the face is minimized due to the special structure, ie, a hard base layer 26, in the cutting area and a smooth sliding layer 20 in the discharge area of the grooves 4, 5, and the formation of an edge is prevented increased. Furthermore, by producing the slidable layer 20 on the open face 10 of the tool, the friction thereof with the machined surface 34 of the workpiece 30 is minimized so that also the wear of the open face in the area of The cutting edges are reduced to a minimum. Consequently, by providing the sliding layer 20, the wear of the tool can be substantially reduced compared to conventional tools having a sliding layer 20. Thus, such tools are especially advantageous when used for dry machining or for machining. with a reduced amount of light metal coolant (aluminum / magnesium alloys) which is becoming increasingly important in the automotive and aviation industry. When refrigerants and lubricants are eliminated or reduced on the one hand, considerable investment costs can be saved, and on the other hand, the recycling or disposal of such refrigerants / lubricants is a problem that also constitutes a significant cost factor. growing in view of the strict legislative impositions. The superiority of the covered tools to those not covered can be explained by means of the comparative tests shown in figure 6. These tests were carried out with a helical drill covered with TiAIN, the tests being carried out on the basis of identical machining parameters (cutting speed, feeding, depth of cut). The series of tests shown on the left of figure 6 were carried out with a work piece made of A1SÍ9, where an almost triple tool length advance was achieved by providing the tool with a hard base layer and a smooth sliding layer (H + S). The same result was also obtained with an aluminum alloy having a higher content of silicon (A1SÜ8), where although lower total values were achieved due to the worse machinability of this material, however the covered tool exhibited an advance in the considerably longer tool life with equal test conditions in other circumstances. That is, by providing the smooth sliding layer on a hard base layer or a hard base body of a tool, the tool life and thus also the maximum possible cutting speeds can be substantially improved compared to conventional tools. Optimum results can be achieved, when the tool as shown in Figures 1 and 3 is provided with both a slotted section and a smooth sliding layer, where it can be advantageous in individual cases to provide exclusively any of the improvements described (slotted section or sliding layer). When forming the slots 18 and the recesses 14, (depth and width) it is preferred that the spokes vary from 0.01-2 mm, preferably 0.02-0.5 mm. Such grooves 18 and recesses 14 may occur during the oppression of the grooves and the bore fragment, respectively, in a duty cycle such that the oppression and machining operations are not necessarily separated to provide grooves / recesses. The slidable layer 20 can be prepared by pulverized iron so that the layer is not only applied to the surface of the base layer 26 but also partially diffuses into the base layer.

Of course "that the invention is not restricted to use with drilling tools, but the grooved section according to the invention and / or the sliding layer according to the invention are also applicable to other cutting tools, preferably those which They have a geometrically defined cutting face.

Claims (15)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as novelty and therefore what is described in the following claims is claimed as property. A cutting tool, especially a drill, a milling cutter, a threaded nut, a scalar machine, a drill string, comprising an axis and a cutting member (2) in which at least one cutting edge is provided ( 8, 9, 28) for machining a workpiece (30), wherein said cutting member (2) is covered with a sliding layer (20) having a hardness lower than that of the base layer (26) of said cutting member, which is made of wear resistant material with which a base body of said cutting member (2) is covered and said sliding layer (20) contains sulfides, selenides, tellurides, such as MoS2, NbS2 , TaS2, S2, MoSe2, NbSe2, TaSe2, WSe2, MoTe2, NbTe2, Te2 or mixed compounds thereof.
2. 2. A cutting tool according to claim 1, characterized in that said base body (20) of said cutting member (2) is made of HSS, hard metal, cerametal or ceramic material.
3. A cutting tool according to any of claims 1 and 2, characterized in that said base layer (26) consists of ceramic material such as TiN, TiAIN, TiCN, diamond or the like.
4. 4. A cutting tool according to any of claims 1 to 3, characterized in that said sliding layer (20) is not provided in the area of the cutting edge (8, 9).
5. A cutting tool according to any of the preceding claims, characterized in that the thickness of said base layer (26) is 1-10 μ and / or the thickness of said sliding layer (20) is between 0.01-5 μ .
6. A cutting tool according to any of the preceding claims, characterized in that the hardness of said base layer (26) is between 1,000 and 10,000 HV, preferably 2,000 - 4,000 HV and / or said sliding layer (20) has a hardness of Mohs of 1-2.
7. A cutting tool according to any one of the preceding claims, characterized in that in an open space (10) of the cutting tool (2) a plurality of adjacent recesses (14) similar to grooves "extending from the edge" are formed. cutting (8, 9) towards a trailing edge (16) of said open space (14).
8. 8. A cutting tool according to claim 7, characterized in that said cutting edge (8, 9) is formed on the front of said cutting member (2) and said recesses (14) are positioned approximately concentrically with respect to each other. to the axis (27) of the cutting tool.
9. 9. A cutting tool according to claim 8, characterized in that said recesses (14) are segments of a circle or spiral.
10. A cutting tool according to any of the preceding claims, characterized in that in a groove (4, 5) in the area of said cutting edge (8, 9) at least one groove (18) is formed, the axis of which it is preferably parallel to the axis of the grooves (4, 5).
11. 11. A cutting tool according to claim 10, characterized in that "a plurality of corrugated adjacent grooves (18) are formed in said groove (4, 5).
12. 12. A cutting tool according to claim 10 or 11, characterized in that said grooves (18) and / or recesses (14) have an approximately corrugated cross section. A cutting tool according to any of claims 10 to 12, characterized in that each slot (18) is associated with a recess (14) installed in the extension of said slot (18). A cutting tool according to any of claims 10 to 13, characterized in that said grooves (18) and recesses (14) extend over a partial area of said groove (4, 5) and said open face (10), respectively. A cutting tool according to any of claims 10 to 14, characterized in that the amplitude and depth of said grooves (18) and / or said recesses (14) is 0.01-2 mm, preferably 0.02-0.5 mm.