# US 7,744,025 B2 · Secondary grinding section for an orifice plate of a grinding machine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,744,025 B2 - Document ID: US7744025B2 - Status: Granted - Kind: B2 - Application number: 11/551,224 - Filed: 2006-10-19 - Published: 2007-04-26 - Granted: 2010-06-29 - Earliest claimed: 2005-10-20 - Assignees: Weiler and Company, Inc. - Inventors: Christopher E. Albrecht; Nick J. Lesar - Web page: https://patentgrep.com/patent/US7744025B2 ## CPC - B02C 18/302: {with a knife-perforated disc unit} - B02C 18/365: {Perforated discs} - B02C 2018/308: {with separating devices for hard material, e.g. bone} - B02C: CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN ({household tools and machines for pulverising foodstuffs, e.g. coffee and spice mills A47J42/00; pharmaceutical mortars A61J3/02; mechanical processing of refuse and garbage B03B9/06; dressing mould materials by grinding B22C5/04}; obtaining metallic powder by crushing, grinding or milling B22F9/04; {recovery of plastics by disintegrating B29B17/00; crushing raw materials in starch making C08B30/02; beaters for papermaking D21D1/02; crushing devices specially for transport in mines E21F13/002; slag crushing devices F23J1/00; fuel milling devices in combustion apparatus F23K1/00; household devices for crushing coal F24B15/02; ice disintegrating devices F25C5/02}) ## Abstract An orifice plate with an outer grinding section and an inner grinding section is disclosed. The outer grinding section is the main grinding section leading to the main material collection stream, and an additional grinding section is present in the inner section of the orifice plate to remove useable material from material swept toward the center of the plate by the action of a rotating knife assembly on the plate. The useable material obtained at the inner section is also led to the main material collection stream. ## Claims ### Claim 1 A grinding machine for grinding material that includes a combination of hard material and soft material, comprising a rotatable knife assembly and an orifice plate having a grinding surface and a series of outer primary grinding orifices that cooperate with the knife assembly to grind material supplied to the grinding surface, wherein the orifice plate includes an inner section having a plurality of spaced apart collection passages extending therethrough that are larger than the primary grinding orifices and are designed to collect hard material, wherein the outer primary grinding orifices are located in an outer section of the orifice plate located radially outward of the collection passages, and wherein the inner section of the orifice plate further includes an inner orifice section having a plurality of secondary grinding orifices that are smaller than the collection passages and are located inwardly of the primary grinding orifices and between the collection passages. ### Claim 2 (depends on 1) The grinding machine of claim 1, wherein material discharged from the primary grinding orifices is supplied to a ground material discharge cavity located downstream of the orifice plate and wherein the material discharged from the plurality of collection passages is supplied to a hard material collection cavity that is isolated from the ground material discharge cavity, and wherein the inner grinding section is located on the orifice plate such that material discharged from the secondary grinding orifices of the inner grinding section is supplied to the ground material discharge cavity. ### Claim 3 (depends on 2) The grinding machine of claim 2, wherein the hard material collection cavity is defined by a hard material collection housing located downstream of the orifice plate, wherein the hard material collection housing is configured to isolate the hard material collection cavity from the ground material collection cavity. ### Claim 4 (depends on 3) The grinding machine of claim 3, wherein the hard material collection housing includes a side wall which at least in part defines the hard material collection cavity, wherein the side wall defines an upstream end located adjacent a downstream surface defined by the orifice plate, and wherein the side wall is configured so as to establish communication between the secondary grinding orifices and the ground material collection cavity. ### Claim 5 (depends on 4) The grinding machine of claim 4, wherein the outer section of the orifice plate, which includes the outer primary grinding orifices, is arranged annularly around the inner section of the orifice plate, which includes the plurality of collection passages and the secondary grinding orifices. ### Claim 6 (depends on 5) The grinding machine of claim 5, wherein the upstream end of the side wall of the hard material collection housing is located inwardly of the outer section of the orifice plate that includes the primary grinding orifices, wherein the side wall of the hard material collection housing includes a clearance structure that exposes the secondary grinding orifices to the ground material collection cavity. ### Claim 7 (depends on 6) The grinding machine of claim 6, wherein the rotatable knife assembly is configured to pass over the primary grinding orifices and the secondary grinding orifices. ### Claim 8 An orifice plate for a grinder for grinding material that includes a combination of hard material and soft material, comprising an outer grinding section with primary grinding openings that are configured to interact with a rotating knife assembly to grind material supplied to the orifice plate, and an inner section having a plurality of spaced apart hard material collection passage larger than the primary grinding openings and designed to collect hard material, wherein the outer primary grinding orifices are located in an outer section of the orifice plate located radially outward of the collection passages, and wherein the inner section of the orifice plate further includes an inner orifice section having a plurality of secondary grinding orifices that are smaller than the collection passages and are located inwardly of the primary grinding orifices and between the collection passages. ### Claim 9 (depends on 8) The orifice plate of claim 8, wherein the orifice plate is adapted to be positioned in a grinding machine in which material discharged from the primary grinding orifices is supplied to a ground material discharge cavity located downstream of the orifice plate, material discharged from the plurality of collection passages is supplied to a hard material collection cavity that is isolated from the ground material discharge cavity, and material discharged from the secondary grinding orifices of the inner grinding section is supplied to the ground material discharge cavity. ### Claim 10 (depends on 8) The orifice plate of claim 8, wherein the outer primary grinding orifices of the orifice plate are arranged in an annular configuration on the outer section of the orifice plate and the secondary grinding orifices are located in the inner orifice section, wherein an outer perimeter of the inner orifice section is defined by an inner margin of the primary grinding orifices.