Grinding element, method for producing the grinding element and injection-molding tool for carrying out the method

Abstract

A grinding element consists of a disk-shaped main body and blades formed as a unit therewith, wherein the main body and the blades are made of sintered hard material. An opening passing through the main body is arranged immediately in front of each blade with respect to a direction of rotation of the grinding element about a center axis. Each blade has a rake face that is partially cylindrical with a rake angle α=0° or partially conical with a rake angle α≠0°.

1 - 23 . (canceled) 
     
     
         24 . A grinding element consisting of a disk-shaped main body and cutting elements formed as a unit therewith, wherein the main body and the blades are made of sintered hard material, wherein, in relation to a direction of rotation of the grinding element about a center axis, each blade is immediately preceded by an opening passing through the main body , and wherein each blade has a rake face having one of the group comprising a partially cylindrical shape with a rake angle α=0° and a partially conical shape with a rake angle α≠0°. 
     
     
         25 . A grinding element, wherein when the rake face has a partially conical shape, the following applies: −30°≦α≦30°. 
     
     
         26 . The grinding element according to  claim 24 , wherein the openings are arranged, with their respective axes, on a first curve, which, seen from a starting point adjacent to the center axis to an outer end, has the shape of a spiral. 
     
     
         27 . The grinding element according to  claim 26 , wherein the first curve has the shape of an Archimedean spiral. 
     
     
         28 . The grinding element according to  claim 26 , wherein the first curve has the shape of a spiral with a progressive pitch towards the outer end. 
     
     
         29 . The grinding element according to  claim 26 , wherein openings are provided that are arranged on a second curve adjoining the outer end of the first curve and extending in the shape of a partial spiral across less than a circumference of the main body. 
     
     
         30 . The grinding element according to  claim 25 , wherein openings are provided that are arranged on an outer circular curve. 
     
     
         31 . The grinding element according to  claims 24 , wherein openings arranged immediately adjacent to each other on the at least one curve have identical distances a from each other. 
     
     
         32 . The grinding element according to  claim 24 , wherein, in relation to an x-y-z coordinate system the z-axis of which is congruent with the axis of a respective opening and the y-axis of which runs through the center axis and the axis of the respective opening, in other words radially to the center axis, and the x-axis of which runs perpendicularly to the y-axis and to the z-axis, the cutting edge extends, in relation to the x-axis, outwardly across an angle γ and inwardly across an angle β, wherein: 0°≦γ<45° and 0°≦β≦45°. 
     
     
         33 . The grinding element according to  claim 24 , wherein the blades taper towards a rear end section in a direction counter to the direction of rotation, and wherein the respective end section is arranged on the main body in a position opposite to the respective x-axis and inwardly offset towards the center axis. 
     
     
         34 . The grinding element according to  claim 24 , wherein the blades have a height b above the main body ( 25 ), wherein 0.1 mm≦b≦10 mm. 
     
     
         35 . The grinding element according to  claim 24 , wherein the hard material is crystalline. 
     
     
         36 . The grinding element according to  claim 24 , wherein the blades and the main body consist of a hard material in the form of one of the group comprising Al 2 O 3  and ZrO 2  and Si 3 N 4  and SiC and a hard metal. 
     
     
         37 . The grinding element according to  claim 36 , wherein said hard metal is WC—Co. 
     
     
         38 . The grinding element according to  claim 24 , wherein the sintered hard material has a grain size k, wherein 0.1 μm≦k 15 μm. 
     
     
         39 . A method for the production of a grinding element consisting of a disk-shaped main body and blades formed as a unit therewith, wherein the main body and the blades are made of sintered hard material, wherein, in relation to a direction of rotation of the grinding element about a center axis, each blade is immediately preceded by an opening passing through the main body, and wherein each blade has a rake face having one of the group comprising a partially cylindrical shape with a rake angle α=0° and a partially conical shape with a rake angle α≠0°,
 wherein an initial material is produced by kneading and mixing from an organic binding agent that becomes moldable when heated and hard material in the form of particles, 
 wherein, in a subsequent step, a raw component of the grinding element is produced by injection molding, 
 wherein, in a subsequent step, the binding agent is removed from the 20 raw component, and 
 wherein, in a subsequent step, the grinding element is formed from the raw component in a sintering process. 
 
     
     
         40 . The method according to  claim 39 , wherein the hard material used is in the form of particles of one of the group comprising Al 2 O 3  and ZrO 2  and Si 3 N 4  or and SiC and hard metal. 
     
     
         41 . The method according to  claim 40 , wherein said hard metal is WC—Co. 
     
     
         42 . The method according to  claim 40 , wherein the following organic high polymers are used as binding agent: one of the group comprising polyolefins, polyamides and polyacrylates. 
     
     
         43 . The method according to  claim 40 , wherein the binding agent is removed from the raw component by at least one of the group comprising heat and solvents. 
     
     
         44 . The method according to  claim 43 , wherein the binding agent is removed by application of heat under the following conditions:
 when using one of the group comprising Al 2 O 3  and ZrO 2  and Si 3 N 4  and WC—Co particles at a temperature of 510° C. in the presence of ambient air, and   when using SiC particles at a temperature of 280° C. to 1000° C. in one of the group comprising an inert gas atmosphere and vacuum.   
     
     
         45 . The method according to  claim 40 , wherein sintering takes place under the following conditions when using:
 Al 2 O 3  and ZrO 2 : 1300° C. to 1700° C. under atmosphere, without pressure;   SiC: 1900° C. to 2200° C. in an argon inert gas atmosphere, without pressure;   Si 3 N 4 : 1600° C. to 1800° C. in a nitrogen inert gas atmosphere, 7 to 50 bar; and   WC—Co: 1250° C. to 1500° C. in an argon inert gas atmosphere, 1 to 50 bar.   
     
     
         46 . An injection-molding tool for the production of the grinding element consisting of a disk-shaped main body and blades formed as a unit therewith, wherein the main body and the blades are made of sintered hard material,
 wherein, in relation to a direction of rotation of the grinding member about a center axis, each blade is immediately preceded by an opening passing through the main body, and   wherein each blade has a rake face having one of the group comprising a partially cylindrical shape with a rake angle α=0° and a partially conical shape with a rake angle α≠0°,   using a method   wherein an initial material is produced by kneading and mixing from an organic binding agent that becomes moldable when heated and hard material in the form of particles,   wherein, in a subsequent step, a raw component of the grinding member is produced by injection molding,   wherein, in a subsequent step, the binding agent is removed from the raw component, and   wherein, in a subsequent step, the grinding member is formed from the raw component in a sintering process,   wherein two tool components are provided that define a molding space when the injection-molding tool is closed,   wherein bolts are arranged on one tool component for molding the openings and the rake faces, the bolts engaging drill holes of the other tool component when the injection-molding tool is closed, and   wherein recesses are formed in one tool component for molding the blades.   
     
     
         47 . The injection-molding tool according to  claim 46 , wherein one tool component is formed in two pieces with the molding plate defining the molding space, wherein the molding plate comprises the recess for molding the blades and drill holes penetrated by the bolts. 
     
     
         48 . The injection-molding tool according to  claim 46 , wherein the bolts are have one of the group comprising a cylindrical and a conical shape in the region of the recess.