# US 5,350,288 A · Injection molding unit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,350,288 A - Document ID: US5350288A - Status: Granted - Kind: A - Application number: 08/139,026 - Filed: 1993-10-21 - Granted: 1994-09-27 - Earliest claimed: 1992-10-22 - Assignees: Daiho Industrial Co., Ltd.; Dainichi Mold Manufacturing Co., Ltd. - Inventors: Hidetoshi Kimoto; Isao Shihota - Web page: https://patentgrep.com/patent/US5350288A ## CPC - B29C 45/77: of velocity or pressure of moulding material - B29C 45/2669: {with means for removing excess material, e.g. with overflow cavities (B29C45/1711 takes precedence)} - B29C 45/58: Details - 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 An injection molding unit has an injection molding machine 1 for injecting a molten resin plasticized in a screw cylinder 4 from a nozzle 9 fitted at the tip of the screw cylinder 4 by advancing a screw 3. An injection mold 31 forms a hollow 36 for forming an injection molded product 35 with a cavity mold 33 and a core mold 34. The injection molding unit further has a pressure relief valve 40 for releasing the resin out of a resin passage when a pressure greater than a predetermined value acts at any point on the resin passage, including the screw cylinder and ranging up to the terminal end of the hollow. The cavity mold 33 is of a split construction, in which a wall portion of the hollow is formed a plurality of segments. ## Claims ### Claim 1 An injection molding unit comprising an injection molding machine for injecting a molten resin plasticized in a screw cylinder from a nozzle fitted at a tip of said screw cylinder by advancing the screw to a molding cavity of an injection mold having a cavity mold and core mold having a hollow therebetween to produce an injection molded part, wherein the injection molding unit further comprises: pressure relief means for releasing the molten resin out of a resin passage when a pressure measured at any point on said resin passage is greater than a corresponding predetermined value, said resin passage extending between the screw cylinder and a terminal end of the core mold; and the cavity mold being formed by a plurality of mold segments forming wall portions of the hollow. ### Claim 2 (depends on 1) The injection molding unit of claim 1, wherein said resin passage includes a runner in said injection mold and said pressure relief means is located along said resin passage upstream of said runner. ### Claim 3 An injection molding unit, comprising: an injection molding machine for injecting plasticized molten resin, said injection molding machine including a screw cylinder having a tip, a nozzle at said tip and a screw advanceable in said screw cylinder for injecting molten resin from said nozzle; an injection mold comprising a cavity mold and a core mold forming a hollow therebetween for forming an injection molded product therein; a resin passage extending from inside said screw cylinder to a terminal end of said hollow; and a pressure relief means for releasing molten resin from said resin passage at a pressure of the molten resin in said resin passage greater than a predetermined value; wherein said cavity mold comprises a plurality of cavity mold segments defining respective wall portions of said hollow. ### Claim 4 (depends on 3) The injection molding unit of claim 3, wherein said resin passage includes a runner in said injection mold and said pressure relief means is located along said resin passage upstream of said runner. ### Claim 5 (depends on 3) The injection molding unit of claim 3, wherein said pressure relief means comprises a hole communicating with said resin passage, a valve having a valve member biased into said hole, and a relief passage communicating with said hole. ### Claim 6 (depends on 5) The injection molding unit of claim 5, wherein said valve has a spring biasing said valve member into said hole. ### Claim 7 (depends on 5) The injection molding unit of claim 5, wherein said valve has a diaphragm biasing said valve member into said hole, said diaphragm being breakable at said pressure greater than the predetermined valve. ### Claim 8 (depends on 5) The injection molding unit of claim 5, wherein said resin passage includes a runner in said injection mold and said hole communicates directly with said runner. ### Claim 9 (depends on 5) The injection molding unit of claim 5, wherein said hole communicates directly with said hollow. ### Claim 10 (depends on 3) The injection molding unit of claim 3, wherein said pressure relief means is located on said screw cylinder. ### Claim 11 An injection molding unit, comprising: an injection molding machine for injecting plasticized molten resin, said injection molding machine including a screw cylinder having a tip, a nozzle at said tip and a screw advanceable in said screw cylinder for injecting molten resin from said nozzle; an injection mold comprising a cavity mold and a core mold forming a hollow therebetween for forming an injection molded product therein; a resin passage extending from inside said screw cylinder to a terminal end of said hollow; and a pressure relief valve located on said resin passage and adapted to release molten resin from said resin passage at a pressure of the molten resin in said resin passage greater than a predetermined value; wherein said cavity mold comprises plurality of cavity mold segments defining respective wall portions of said hollow. ### Claim 12 (depends on 11) The injection molding unit of claim 11, wherein said resin passage includes a runner in said injection mold and said pressure relief valve is located along said resin passage upstream of said runner. ### Claim 13 (depends on 11) The injection molding unit of claim 11, wherein said pressure relief valve comprises a hole communicating with said resin passage, a valve member biased into said hole, and a relief passage communicating with said hole. ### Claim 14 (depends on 13) The injection molding unit of claim 13, wherein said valve has a spring biasing said valve member into said hole. ### Claim 15 (depends on 13) The injection molding unit of claim 13, wherein said valve has a diaphragm biasing said valve member into said hole, said diaphragm being breakable at said pressure greater than the predetermined valve. ### Claim 16 (depends on 13) The injection molding unit of claim 13, wherein said resin passage includes a runner in said injection mold and said hole communicates directly with said runner. ### Claim 17 (depends on 13) The injection molding unit of claim 13, wherein said hole communicates directly with said hollow. ### Claim 18 (depends on 11) The injection molding unit of claim 11, wherein said pressure relief valve is located on said screw cylinder.