WO2013037967A1

WO2013037967A1 - Cutting tool with wear-recognition layer

Info

Publication number: WO2013037967A1
Application number: PCT/EP2012/068141
Authority: WO
Inventors: Sebastian HAMPSCH; Jörg Drobniewski
Original assignee: Walter Ag
Priority date: 2011-09-16
Filing date: 2012-09-14
Publication date: 2013-03-21
Also published as: DE102011053716A1

Abstract

The present invention relates to a tool, consisting of a substrate body, preferably made of hard metal, cermet, ceramic, steel or high-speed steel and optionally a single-layer or multi-layer wear protection coating deposited on the substrate body, and to a method for producing the tool. In order to provide a coating on the tool with a decorative and/or indicator function that can be produced comparatively simply and inexpensively, allows an improved wear recognition, is temperature-stable, has fewer tribologically unfavourable effects on the cutting process and the wearing behaviour of the tool and can simultaneously be produced in a wider variety of colours than other known wear recognition coatings, the invention proposes a wear-recognition layer arranged as the outermost layer above the substrate body or the wear-protection coating and having, in the direction from the substrate body to the outer surface of the tool, a first area consisting of a metal or an electrically conductive metal compound and, adjacent to the first area, a second area consisting of an oxidized form of the metal or conductive metal compound of the first area, produced by anodic oxidation, the second area extending up to the outer surface of the wear recognition layer.

Description

Cutting tool with wear detection layer

Subject of the invention

The present invention relates to a tool consisting of a substrate body, preferably made of hard metal, cermet, ceramic, steel or high-speed steel, and optionally a deposited on the substrate body single or multi-layer wear protection coating, as well as a method for manufacturing the tool.

Background of the invention

Cutting tools, in particular those for metal cutting machining, which include in particular interchangeable cutting inserts and cutting inserts, consist of a substrate or base body with an optionally deposited thereon single or multilayer coating. The substrate is usually made of hard metal, cermet, ceramic, steel or high-speed steel and the coating of hard materials, which are applied by CVD or PVD process. The coating with hard materials is intended to improve the cutting properties of the tool for a particular application and to reduce the wear of the tool.

It is also known to provide the cutting tools with a mostly thin outermost layer with a decor and / or indicator function, for example an outermost layer of TiN, ZrN, TiC, HfC or HfN, which differs colorably from the underlying anti-wear layer. Such layers can serve in addition to purely decorative purpose with advantage also the wear detection, as they wear out during use of the tool and the underlying layer is visible, which can already be seen with the naked eye, whether and how intense a tool has already been used. EP 1 762 638 describes a cutting insert comprising a cemented carbide substrate and a multilayer hard coating for wear protection and an outermost indicator layer of ZrN, which is first applied in a thickness of <1 μm by means of PVD and then by the rake face and the cutting edge by brushing or blasting is removed again, there the layer of ZrN as such has unfavorable tribological properties which may adversely affect the cutting properties at the cutting edge and rake surface.

DE 10 2004 010 285 and DE 100 48 899 likewise describe cutting tools with an indicator cover layer of golden yellow TiN or also of TiC, HfC or HfN, which differ in color from the wear protection layer arranged underneath and make it possible to use a used cutting tool from an unused one to distinguish with the naked eye. The color variation width of the known cover layers with decor and / or indicator function (hereinafter referred to as wear detection layers for simplicity) is extremely limited. The nitrides and carbides used very often for wear detection layers, for example, have a golden yellow color. In addition, some of the known wear detection layers have adverse tribological properties that adversely affect the cutting process and tool wear behavior. In addition, some of the known materials used for the production of wear-detecting layers are not sufficiently stable under the high temperatures encountered in many metal working processes or under the temperature changes associated with certain metal working processes.

task

The invention was therefore based on the object of providing a coating for cutting tools with a decor and / or indicator function (wear detection layer) which is comparatively simple and inexpensive to produce, allows improved wear detectability, is temperature-stable, has less tribologically unfavorable influences on the cutting process and the wear behavior of the tool and at the same time in a wider variety of colors than known wear detection coatings can be produced. Description of the invention

According to the invention this object is achieved by a tool consisting of a substrate body, preferably made of hard metal, cermet, ceramic, steel or high-speed steel, and optionally a deposited on the substrate body one or more layers wear protection coating, wherein as outermost layer above the substrate body or the Wear protection coating, a wear detection layer is arranged, which in the direction of the substrate body to the outer surface of the tool has a first region which consists of a metal or an electrically conductive metal compound, and adjacent to the first region having a second region consisting of an oxidized form of the metal or the electrically conductive metal compound of the first region produced by anodic oxidation, wherein the second region extends to the outer surface of the wear detection layer.

The wear detection layer according to the invention has significant advantages over known decor and indicator layers, such as TiN, which has disadvantages as a coating for tools for processing such materials because of its high affinity for example cast iron. The wear-detection layer according to the invention has oxidic properties on its surface and in the region of the wear-detection layer designated herein as the second region, which may have significant advantages over known nitride or carbide layers from a tribological point of view. Thus, these tribologically advantageous properties reduce unfavorable influences on the machining properties and the wear behavior of the tool.

Depending on the metal used or the electrically conductive metal compound used and the extent of the anodic oxidation and the layer thickness, the wear detection layers according to the invention are good to high degree thermally stable, which is why they are tools for metal cutting, often with very high temperatures or temperature cycling occur, especially suitable.

A further advantage of the wear-detection layers according to the invention is that, depending on the metal used or the electrically conductive metal compound used, they provide a very intense color effect which can be achieved even at very low layer thicknesses. Depending on the metal or electroconductive metal compound used and the degree of anodic oxidation that emanates from the outer layer surface and extends in the direction of the substrate body to a depth depending on the parameters of the oxidation process, a very wide variety of different colors and brightnesses that cover almost the entire visible color spectrum. In this way not only the wear detection serving outer surface layers can be made, but tools can also be characterized by different colors, so that the user can distinguish different types of tools or types of tools already based on the color. The wear detection layer according to the invention can thus serve exclusively or in addition to the wear detection function also a color coding of tools.

Without the inventors being able to be bound by theory, they assume that the color effect of the wear-detection layer according to the invention is based on the reflection of light which is incident on the metallic or electrically conductive metal compound first region of the wear detection layer by the second region (outer region) of the wear detection layer made by anodic oxidation. Interference effects provide the color to be observed. In special cases, however, the color effect can also be based on the intrinsic color of the anodically oxidized second region of the wear-detection layer.

In one embodiment of the tool according to the invention, the wear detection layer has a layer thickness of 0.1 nm to 20 μηη, preferably from 1 nm to 5 μηη, more preferably from 20 nm to 2 μηι on. A particular advantage of the present invention is that even with extremely thin layers good color effects can still be achieved.

In a further embodiment of the tool according to the invention, the first region of the wear detection layer made of a metal or an electrically conductive metal compound has a layer thickness of 0.05 nm to 10 μm, preferably 0.5 nm to 2.5 μm, particularly preferably 10 nm to 1, 5 μηη on.

In a further embodiment of the tool according to the invention, the second region of the wear detection layer of an oxidized form of the metal or the electrically conductive metal compound of the first region has a layer thickness of 0.05 nm to 10 μm, preferably 0.5 nm to 2.5 μηη, more preferably from 10 nm to 0.5 μηη on.

The thickness of the wear detection layer according to the invention can be very thin overall. The thickness of the anodically oxidized second region of the wear-detection layer, in addition to the selection of the metal or the electrically conductive metal compound, has a considerable influence on the coloration, in particular on the color tone and the brightness. For example, a wear detection layer made of titanium may vary with the extent of anodic oxidation, i. the thickness of the second area, with the same total thickness of the wear detection layer have a color from purple to green or a very different color.

In a further embodiment of the tool according to the invention, a single-layer or multi-layer, preferably a multi-layer wear protection coating is arranged on the substrate body under the wear detection layer, which preferably comprises at least one electrically non-conductive layer, which is particularly preferably an aluminum oxide layer.

The application of the wear detection layer according to the invention over a non-conductive wear protection layer, most preferably over a Alum miniumoxid- layer, due to their hardness and wear resistance in many tools for Metal cutting machining is advantageously used as an outer wear protection layer, has the particular advantage that it can not come to so-called breakdowns in the anodization process in the process of anodic oxidation of the wear detection layer due to the non-conductive layer arranged underneath. The wear detection layer can then be made very thin.

In a further embodiment of the tool according to the invention, in the wear detection layer, the metal or the metal contained in the electrically conductive metal compound is Nb, Ti, Zr, Al, Ta, W, Hf, V, Mo, Si and alloys of the aforementioned metals. Preferably selected from Nb, Ti, Zr, Al and alloys of the aforementioned metals. At the same time or alternatively, in another embodiment of the tool according to the invention, the metal compound of the wear-detection layer is selected from nitrides, carbides and borides of the aforementioned metals, provided that this metal compound is electrically conductive. In a further embodiment of the tool according to the invention, the wear detection layer is produced by applying a layer of a metal or an electrically conductive metal compound to the substrate body or to the one or more layers of wear protection coating deposited on the substrate body, preferably by PVD or CVD methods, and subsequent anodic oxidation of the layer of the metal or the electrically conductive metal compound in an electrolyte bath.

Very particular preference is given to depositing metals, but also the electrically conductive metal compounds, on the tool body in the PVD method, since PVD coating systems are often already equipped with different metal targets in order to apply the hard material layers serving for wear protection to the substrate body. Without interrupting the coating process can then easily and inexpensively apply the desired for the production of the wear detection layer metal or the electrically conductive metal compound as the outermost layer in such systems. In a further embodiment of the tool according to the invention, the anodic oxidation takes place in the electrolyte bath at a DC voltage and for a period of time which are selected so that the anodic oxidation from the outer surface of the layer of the metal or the electrically conductive metal compound to a penetration depth of Layer is less than the total thickness of the wear detection layer.

In a further embodiment of the tool according to the invention, the anodic oxidation takes place in the electrolyte bath at a DC voltage and for a period of time which is thus are chosen such that the layer of the metal or the electrically conductive metal compound is oxidized over the full thickness of the wear detection layer.

In a further embodiment of the tool according to the invention, the wear detection layer has been removed from selected regions of the tool, for example from the cutting edge and / or the rake face, preferably by abrasive blasting with a particulate abrasive, by grinding or by brushing.

The invention also encompasses a method for producing a tool according to the invention described above having a wear detection layer which comprises a tool made of a substrate body, preferably of hard metal, cermet, ceramic, steel or high-speed steel, and optionally of a deposited on the substrate body. or multilayer anti-wear coating applies a layer of a metal or an electrically conductive metal compound, preferably by PVD or CVD, and then subjecting the layer of the metal or electrically conductive metal compound of the coated tool to anodic oxidation in an electrolyte bath. The process is simple and inexpensive and offers the possibility to produce many different colors. In one embodiment of the method according to the invention, the anodization is carried out at a DC voltage and for a period of time which are selected such that the anodic oxidation takes place from the outer surface of the layer of the metal or of the electrically conductive metal compound to a penetration depth of the layer, which is less than the total thickness of the wear detection layer.

In an alternative embodiment of the method according to the invention, the anodization is carried out at a DC voltage and for a period of time which are selected such that the anodic oxidation of the layer of the metal or of the electrically conductive metal compound takes place over the total thickness of the wear detection layer.

Further advantages, features and applications of the present invention will become apparent from the following description of a figure and preferred embodiments.

EXAMPLES

In a PVD coating machine (Flexicoat; Hauzer Techno Coating), carbide substrates having a wear protection coating with an outermost layer of Al ₂ O _{3 were included} a 1, 5 μηι thick outermost layer of titanium metal provided. Subsequently, the coated cemented carbide _{substrates were} subjected to anodic oxidation in an electrolytic _bath containing 1 mol / L of citric acid for an anodization time t _an0d = 30 seconds at different voltages. The thickness of the oxide formed by the anodic oxidation was substantially proportional to the applied voltage. At the applied voltage of 50 V, the wear detection layer of the tool received a blue color, whereas at the voltage of 120 V, it received a green color.

For purposes of the original disclosure, it is to be understood that all such features as will become apparent to those skilled in the art from the present description and the dependent claims, even though they have been specifically described in connection with certain further features, both individually and in any combination with other features or groups of features disclosed herein can be combined, unless this has been expressly excluded or technical conditions make such combinations impossible or pointless. On the comprehensive, explicit representation of all conceivable combinations of features is omitted here only for the sake of brevity and readability of the description.

Claims

P a n t a n s p r e c h e

Tool, consisting of a substrate body, preferably made of hard metal, cermet, ceramic, steel or high-speed steel, and optionally deposited on the substrate body single or multi-layer wear protection coating, characterized in that as the outermost layer above the substrate body or the wear protection coating, a wear detection layer is arranged, which has a first region consisting of a metal or an electrically conductive metal compound in the direction from the substrate body to the outer surface of the tool, and has a second region adjacent to the first region which consists of an oxidized form of the metal produced by anodic oxidation or the electrically conductive metal interconnect of the first region, wherein the second region extends to the outer surface of the wear detection layer.

Tool according to claim 1, characterized in that the wear detection layer has a layer thickness of 0.1 nm to 20 μιη, preferably from 1 nm to 5 μιη, more preferably from 20 nm to 2 μιτι.

Tool according to one of the preceding claims, characterized in that the first region of the wear detection layer of a metal or an electrically conductive metal compound has a layer thickness of 0.05 nm to 10 μιη, preferably from 0.5 nm to 2.5 μιη, more preferably from 10 nm to 1, 5 μιη has.

Tool according to one of the preceding claims, characterized in that the second region of the wear detection layer of an oxidized form of the metal or the electrically conductive metal compound of the first region has a layer thickness of 0.05 nm to 10 μιη, preferably from 0.5 nm to 2, 5 μιη, more preferably from 10 nm to 0.5 μιη.

Tool according to one of the preceding claims, characterized in that on the substrate body under the wear detection layer a single or multi-layer, preferably a multi-layer wear protection coating is arranged, which preferably comprises at least one electrically non-conductive layer, which is particularly preferably an aluminum oxide layer.

Tool according to one of the preceding claims, characterized in that in the wear detection layer, the metal or the metal contained in the electrically conductive metal compound among Nb, Ti, Zr, Al, Ta, W, Hf, V, Mo, Si and alloys the aforementioned metals, preferably Nb, Ti, Zr, Al and alloys of the aforementioned metals is selected and / or the metal compound of the wear detection layer among nitrides, carbides and borides of the aforementioned metals, if this metal compound is electrically conductive, is selected.

Tool according to one of the preceding claims, characterized in that the wear detection layer is prepared by applying a layer of a metal or an electrically conductive metal compound on the substrate body or on the deposited on the substrate body one or more layers Verschleißschutzbe- coating, preferably by PVD method or CVD method, and then anodic oxidation of the layer of the metal or the electrically conductive metal compound in an electrolyte bath.

A tool according to claim 7, characterized in that the anodic oxidation takes place in the electrolyte bath at a DC voltage and for a period of time which are selected such that the anodic oxidation from the outer surface of the layer of the metal or the electrically conductive metal compound to a Penetration depth of the layer is less than the total thickness of the wear detection layer.

Tool according to claim 7, characterized in that the anodic oxidation takes place in the electrolyte bath at a DC voltage and for a period of time which are selected so that the layer of the metal or the electrically conductive metal compound is oxidized over the full thickness of the wear detection layer.

Tool according to one of the preceding claims, characterized in that the wear detection layer has been removed from selected areas of the tool, preferably by abrasive blasting with a particulate abrasive, by grinding or by brushing.

Method for producing a tool having a wear detection layer according to one of the preceding claims, wherein the tool is made of a substrate body, preferably of hard metal, cermet, ceramic, steel or high-speed steel, and optionally a single or multi-layer wear protection coating deposited on the substrate body applying a layer of a metal or an electrically conductive metal compound, preferably by PVD method or CVD method, and then subjecting the layer of the metal or the electrically conductive metal compound of the coated tool to anodic oxidation in an electrolyte bath. The method of claim 1 1, wherein the anodization is performed at a DC voltage and for a time period selected such that the anodic oxidation from the outer surface of the layer of the metal or the electrically conductive metal compound to a penetration depth of the layer which is less than the total thickness of the wear detection layer.

The method of claim 1 1, wherein the anodization is performed at a DC voltage and for a time period selected to effect the anodic oxidation of the metal or electrically conductive metal compound layer over the total thickness of the wear detection layer.