# US 5,679,380 A · Underwater pelletizing die plate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,679,380 A - Document ID: US5679380A - Status: Granted - Kind: A - Application number: 08/623,920 - Filed: 1996-03-28 - Granted: 1997-10-21 - Earliest claimed: 1995-04-27 - Assignees: Werner & Pfleiderer - Inventors: Rainer Munz; Rainer Sauter - Web page: https://patentgrep.com/patent/US5679380A ## CPC - B29B 9/065: {under-water, e.g. underwater pelletizers} - B29B 7/582: {for discharging, e.g. doors} - B29B 7/82: Heating or cooling - B29C 48/05: Filamentary, e.g. strands - B29C 48/345: Extrusion nozzles comprising two or more adjacently arranged ports, for simultaneously extruding multiple strands, e.g. for pelletising - B29C 48/04: Particle-shaped (making granules B29B9/00) - B29C 2793/009: after shaping - B29B: PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS - 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) ## Abstract In an underwater pelletizing die plate or an extruder for the pelletizing of thermoplastics, the front face of the die plate, which is provided with a wearing protection layer and over which pass the pelletizing knives, being disposed under water, and heat isulation means being provided on the pelletizing die plate, good axial insulation is to be achieved, accompanied by uniform temperature distribution in the radial direction, it being provided to this end that an insulating layer is disposed between the external upper side of the actual pelletizing die plate and the wearing protection layer, the wearing protection layer being positioned, relative to the insulating layer, with radial play and without axial pressure or with little axial pressure, respectively. ## Claims ### Claim 1 An underwater pelletizing die plate for an extruder that pelletizes thermoplastics, said die plate comprising said pelletizing die plate defining a plurality of die plate holes extending through a face of said pelletizing die plate, an insulating layer on said face, said insulating layer having a plurality of insulating die holes aligned with said die plate holes, a wear protection layer on said insulating layer, said wear protection layer having a plurality protection layer die holes aligned with said insulating die holes, said protection layer die holes being larger than said insulation die holes, mounting means mounting said wear protection layer on said insulating layer, and wherein when said wear protection layer is cooled radial displacement of said wear protection layer towards the center of said wear protection layer takes place relative to said insulation layer and said die plate. ### Claim 2 (depends on 1) A pelletizing die plate according to claim 1, wherein the insulating layer (17) consists of zirconium oxide. ### Claim 3 (depends on 3) The underwater die plate of claim 3 wherein said mounting means is a screw passing through a wear screw hole and a corresponding insulating screw hole in said insulating layer and into said die plate, said wear screw hole being larger than said screw and said screw being attached to said die plate to hold said wear protection layer on said die plate to allow radial movement of said wear protection layer with respect to said insulating layer. ### Claim 4 (depends on 3) The underwater die plate of claim 3 wherein said screw passes through a retainer and spacer that has an L-shape, said retainer being sized to hold said wear protection layer on said insulation layer and to allow radial movement of said wear layer with respect to said insulation layer. ### Claim 5 (depends on 1) The underwater die plate of claim 1 wherein said mounting means is a spacer and a retainer mounted to said die plate, said spacer and retainer being sized and positioned on said die plate to hold said wear protection layer on said insulation layer and to allow radial movement of said wear layer with respect to said insulation layer. ### Claim 6 (depends on 3) The underwater die plate of claim 3 wherein said insulating layer is zirconium oxide. ### Claim 7 (depends on 4) The underwater die plate of claim 4 wherein said insulating layer is zirconium oxide. ### Claim 8 (depends on 5) The underwater die plate of claim 5 wherein said insulating layer is zirconium oxide. ### Claim 9 In a pelletizing extruder that has an underwater pelletizing die plate and a cutting head having pelletizing knives spaced from said pelletizing die plate to pelletize an extruded material, said die plate said pelletizing die plate defining a plurality of die plate holes extending through a face of said pelletizing die plate, an insulating layer on said face, said insulating layer having a plurality of insulating die holes aligned with said die plate holes, a wear protection layer on said insulating layer, said wear protection layer having a plurality protection layer die holes aligned with said insulating die holes, said protection layer die holes being larger than said insulation die holes, mounting means mounting said protection layer on said insulating layer, and wherein when said wear protection layer is cooled radial displacement of said protection layer towards the center of said wear protection layer takes place relative to said insulation layer and said die plate. ### Claim 10 (depends on 9) In the extruder of claim 9 wherein said mounting means is a screw passing through a wear screw hole, and a corresponding insulating screw hole in said insulating layer and into said die plate, said wear screw hole being larger than said screw and said screw being attached to said die plate to hold said wear protection layer on said die plate to allow radial movement of said wear protection layer with respect to said insulating layer. ### Claim 11 (depends on 10) In the extruder of claim 10 wherein said screw passes through a retainer and spacer that has an L-shape, said retainer being sized to hold said wear protection layer on said insulation layer and to allow radial movement of said protection wear layer with respect to said insulation layer. ### Claim 12 (depends on 9) In the extruder of claim 9 wherein said mounting means is a spacer and a retainer mounted to said die plate, said spacer and retainer being sized and positioned on said die plate to hold said wear protection layer on said insulation layer and to allow radial movement of said wear layer with respect to said insulation layer. ### Claim 13 (depends on 9) In the extruder of claim 9 wherein the insulating layer is zirconium oxide. ### Claim 14 (depends on 10) In the extruder of claim 10 wherein the insulating layer is zirconium oxide. ### Claim 15 (depends on 11) In the extruder of claim 11 wherein the insulating layer is zirconium oxide. ### Claim 16 (depends on 12) In the extruder of claim 12 wherein the insulating layer is zirconium oxide.