# US 5,352,539 A · Extruder housing for double-screw extruder having an annularly stepped internal bore covered by a hot isostatically-pressed structure, and method of making same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,352,539 A - Document ID: US5352539A - Status: Granted - Kind: A - Application number: 07/967,075 - Filed: 1992-10-27 - Granted: 1994-10-04 - Earliest claimed: 1992-10-27 - Assignees: Friedrich Theysohn GmbH - Inventors: Werner G. Psiuk - Web page: https://patentgrep.com/patent/US5352539A ## CPC - B22F 5/10: of articles with cavities or holes, not otherwise provided for in the preceding subgroups - B29C 48/682: {for twin screws} - B30B 11/224: {Extrusion chambers} - C23C 24/08: by application of heat or pressure and heat (C23C24/04 takes precedence) - C23C 26/00: Coating not provided for in groups C23C2/00 - C23C24/00 - B29C 48/03: characterised by the shape of the extruded material at extrusion - Y10T 428/12097: Nonparticulate component encloses particles - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B30B: PRESSES IN GENERAL (producing ultra-high pressure or ultra-high pressure and high temperature to effect modifications of a substance, e.g. for making artificial diamonds B01J3/00 ){(compressing means for refuse receptacles B65F1/1405)} - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An extruder housing is formed for a double-worm or double-screw extruder by providing a steel body with a seamless one-piece structure and hot-isostatically pressing the body and the powder-metallurgical wear-resistant material lining the preferably conical bores of the housing to form a wear-resistant layer which is bonded to the steel body by a diffusion layer. ## Claims ### Claim 1 An extruder housing for a double-screw extruder for processing plastics and synthetic resins, said extruder house comprising: a seamless elongated body formed with a pair of adjacent longitudinally extending generally conical bores for receiving respective conical extruder screws and together defining a figure-eight cross section cavity, each of said bores being provided with a plurality of axially spaced generally annular steps; a wear resistant layer of a hard powder-metallurgical material in a hot isostatic-pressed structure extending along and lining said cavity against said body, said layer filling said steps and having smooth conical walls; and a diffusion layer formed by said material of said layer and material of said body bonding said wear resistant layer to said body. ### Claim 2 (depends on 1) The extruder housing defined in claim 1 wherein both of said bores are conical for receiving conical extruder screws. ### Claim 3 (depends on 1) The extruder housing defined in claim 1 wherein said diffusion layer is formed between said wear-resistant layer and said body over cylindrical portions and transverse portions of respective steps. ### Claim 4 (depends on 1) The extruder housing defined in claim 1, further comprising means for connecting said body with said layers therein to other bodies in the formation of said housing. ### Claim 5 (depends on 1) The extruder housing defined in claim 1 wherein said body and said layers extend the full length of the extruder housing for said double-screw extruder. ### Claim 6 A method of producing an extruder housing comprising the steps of: (a) forming a seamless-elongated body having a pair of adjacent longitudinally-extending bores together defining a figure-eight cross section each of said bores being provided with a plurality of axially spaced generally annular steps; (b) lining said bores with a powder of a hard material capable of hot-isostatic pressing into a coherent layer along said bores and filling said steps with said powder; (c) confining said powder between a pair of conical cores and the walls of said bores; (d) sealing said powder in said body; (e) introducing said body with said cores, and said powder into a pressure vessel and subjecting said powder to hot isostatic pressing by applying pressure from the exterior of said body inwardly and plastically deforming said body, therefore bonding said body into a wear-resistant layer along said bores and forming a diffusion layer of material of said powder and material of said body bonding said wear-resistant layer to said body; and (f) removing said cores to leave smooth conical walls of said layer delimiting smooth cavities for receiving generally conical screws. ### Claim 7 (depends on 6) The method defined in claim 6 wherein the hot isostatic pressing is effected in an inert gas atmosphere at a pressure of at least 1800 bar. ### Claim 8 (depends on 7) The method defined in claim 7 wherein said atmosphere is an argon atmosphere. ### Claim 9 (depends on 6) The method defined in claim 6 wherein the pressure applied to said body from the exterior inwardly is braced against the conical cores. ### Claim 10 (depends on 6) The method defined in claim 6 wherein the hot isostatic pressing is effected without encapsulation of the body or powder within a separate capsule. ### Claim 11 (depends on 6) The method defined in claim 6, further comprising applying to said cores an antiadhesion medium facilitating separation of said cores from said wear-resistant layer. ### Claim 12 (depends on 6) The method defined in claim 6 wherein the hot isostatic pressing is effected at a temperature of about 850.degree. C. to 1200.degree. C. in said chamber.