Annular tool

Abstract

The invention relates to an annular tool ( 1 ) having at least one working region ( 4 ) oriented radially outward and having high wear resistance, and a clamping part ( 5 ) closer to the axis, in particular a roller bit or cutting ring for rock, in particular for tunnel boring machines, made of a material which is formed from an iron-based alloy as matrix having incorporated hard material particles, wherein the hard material particles are formed from carbide and/or nitride and/or oxide and/or boride, possibly as carbonitride or oxycarbonitride having a boron component of at least one of the elements, or in mixed form of the elements from groups 4 and 5 of the periodic system, and have a density at room temperature of more than 7400 kg/m 3 , preferably of more than 7600 kg/m 3 . The invention further relates to methods for the production thereof.

1 . Annular tool ( 1 ) having at least one working region ( 4 ) oriented radially outward with high wear resistance and a clamping part ( 5 ) closer to the axis, in particular a roller bit or cutting ring for rock, in particular for tunnel boring machines, characterized in that the tool is composed of a material that is formed from an iron-based alloy as a matrix with incorporated hard material particles, wherein the hard material particles are formed from carbide and/or nitride and/or oxide and/or boride, possibly as carbonitrides or oxycarbonitride with a boron component, at least of one of the elements, or in mixed form of the elements, from groups 4 and 5 of the periodic system, and have a density at room temperature of greater than 7400 kg/m3, preferably of greater than 7600 kg/m3. 
     
     
         2 . Tool ( 1 ) according to  claim 1 , characterized in that the hard material particles are present in the tool to an extent of at least 5 vol. %, in particular of more than 8 vol. %, wherein the hard material particles are inhomogeneously distributed across the tool cross-section ( 2 ) and have a higher volume fraction in the working region ( 4 ). 
     
     
         3 . Tool ( 1 ) according to  claim 1 , characterized in that the working region ( 4 ) has a volume fraction of at least 8.0%, preferably of at least 14.0%, in particular of approximately 20% to 25%, of the tool ( 1 ), in which working region more than 60 vol. %, preferably more than 75 vol. %, of the hard material particles are formed with a size of less than 70 μm. 
     
     
         4 . Tool ( 1 ) according to  claim 1 , characterized in that the hard material particles are essentially formed as niobium-vanadium mixed carbides, possibly with a nitrogen component, and that they have a ratio of atom % of Nb to atom % of V of greater than 5, preferably greater than 10.
   Nb [atom %]/V [atom %]>5, preferably>10   
     
     
         5 . Tool ( 1 ) according to  claim 1 , characterized in that the matrix alloy has a chemical composition by wt.% within the limits of
 Carbon (C) 0.28 to 2.3   Silicon (Si) 0.01 to 2.0   Manganese (Mn) 0.05 to 25.0   Chromium (Cr) up to 6.0   Nickel (Ni) up to 2.5   Molybdenum (Mo) up to 2.2   Tungsten (W) up to 1.5   (1.5×Mo+W) up to 3.5   Vanadium (V) up to 0.8   Niobium (Nb) up to 0.4   Cobalt up to 3.0   Aluminum (Al) up to 3.0,   possibly   Titanium (Ti) up to 0.2   Zirconium (Zr) up to 0.2   Hafnium (Hf) up to 0.1   Tantalum (Ta) up to 0.25   Iron (Fe) and impurity elements as the remainder.   
     
     
         6 . Tool ( 1 ) according to  claim 5 , characterized in that the matrix alloy is composed of tool steel with a hardness of greater than 44 HRC, preferably of 50 HRC and higher. 
     
     
         7 . Tool ( 1 ) according to  claim 5 , characterized in that the matrix alloy is composed of austenitic manganese steel with a manganese concentration of 6 to 25 wt. % Mn, preferably of 8 to 15 wt. % Mn. 
     
     
         8 . Method for producing annular tools ( 1 ) having at least one working region ( 4 ) oriented radially outward and a clamping part ( 5 ) closer to the axis, in particular roller bits or cutting rings for rock, in particular for tunnel boring machines, formed from an iron-based alloy as a matrix in which hard material particles, such as carbides and/or nitrides and/or carbonitrides and/or borides, possibly in mixed form of the elements from groups 4 and/or 5 of the periodic system, are incorporated, possibly for the production of a tool according to at least one of the preceding claims, wherein a base alloy is melted and heated to a temperature of 1350° C. to 1630° C. in a first step and an addition or a formation of hard material particles with a higher density to or in the melt of the base alloy occurs in a second step, whereupon in a third step, the matrix melt with the hard material particles is subjected to a rotational motion about the longitudinal axis in a mold for the annular tool and is allowed to solidify. 
     
     
         9 . Method according to  claim 8 , wherein in a first step, a base alloy is melted with a chemical composition by wt. % of
 Carbon (C) up to 2.5   Silicon (Si) 0.01 to 3.0   Manganese (Mn) 0.05 to 28.0   Chromium (Cr) up to 9.0   Nickel (Ni) up to 4.3   Molybdenum (Mo) up to 3.5   Tungsten (W) up to 2.2   (1.5×Mo+W) up to 5.1   Vanadium (V) up to 6.0   Niobium (Nb) up to 35.0   Aluminum (Al) up to 3.5,   possibly   Titanium (Ti) up to 2.0   Zirconium (Zr) up to 3.0   Hafnium (Hf) up to 1.0   Tantalum (Ta) up to 5.0   Cobalt (Co) up to 3.0   Iron (Fe) and impurity elements as the remainder.   
     
     
         10 . Method according to  claim 8 , wherein in the second step, the hard material particles, such as carbides and/or nitrides and/or oxycarbonitrides and/or borides, possibly as carbonitrides and/or oxycarbonitrides with boron components, at least of one of the elements, or in mixed form of the elements, from groups 4 and 5 of the periodic system, are introduced into the liquid base alloy by means of a solid or liquid metallic premelt or by means of a similar mixture of metal and hard material particles with a diameter of the hard particles of less than 70 μm and homogeneously distributed in the base alloy, whereupon in the third step, a solidification of the mixture of hard material particles and a matrix alloy, formed from the base alloy and the metal component of the premelt, occurs during rotational motion in the mold. 
     
     
         11 . Method according to  claim 8 , wherein the base alloy with a carbon content of under 0.6 wt. % C is melted and heated to a temperature of 1550° C. to 1630° C., whereupon in a second step, an addition of the alloy elements carbon and/or nitrogen and/or boron, possibly as a pre-alloy, takes place and wherein these elements form, with the dispersed elements from group 4 and/or group 5 of the periodic system, primary carbides and/or nitrides and/or borides and/or compounds or mixtures thereof in the melt, wherein the hard material particles being formed have a total proportion of carbon, nitrogen and boron of atomic ratios from 0.4 to 0.55 and a higher density than the melt, and that 0.3 to 2.3 wt. % of carbon remains in the liquid metal, whereupon in a third step, the melt is subjected to a rotational motion about the longitudinal axis in a mold for the annular tool and is allowed to cool, and a working and a heat treatment of the tool take place in additional steps. 
     
     
         12 . Method according to  claim 11 , wherein the elements from groups 4 and 5 of the periodic system are selected in terms of their respective concentration in the base alloy such that the density of the primarily precipitated hard material particles is greater than that of the melt at a temperature 50° C. above the liquidus temperature.