# US 5,133,591 A · Blow-molded plastic wheel and method for manufacturing same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,133,591 A - Document ID: US5133591A - Status: Granted - Kind: A - Application number: 07/707,690 - Filed: 1991-05-30 - Granted: 1992-07-28 - Earliest claimed: 1991-05-30 - Assignees: Semco Plastic Company - Inventors: Marvin Skaggs; James D. Voelkel - Web page: https://patentgrep.com/patent/US5133591A ## CPC - B29D 99/0032: {Producing rolling bodies, e.g. rollers, wheels, pulleys or pinions (bushes for bearings B29D33/00; gear wheels B29D15/00)} - B29C 33/14: against the mould wall - B29C 49/04102: {extruding the material continuously} - B29C 49/20: of articles having inserts or reinforcements {; Handling of inserts or reinforcements} - B29C 70/26: Non-fibrous reinforcements only {(B29C35/0272, B29C61/0625, B29C70/887 take precedence; combined with fibres B29C70/023)} - B60B 5/02: made of synthetic material - B29C 2049/2017: {outside the article} - B29K 2021/00: Use of unspecified rubbers as moulding material - B29L 2031/32: Wheels, pinions, pulleys, castors or rollers {, Rims (inner tubes B29L2023/245; gears B29L2015/003; tyres B29L2030/00)} - B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00) - 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) - B60B: VEHICLE WHEELS (making wheels or wheel parts by rolling B21H1/00, by forging, hammering or pressing B21K1/28); CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS - B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES ## Abstract The Improved Wheel is suitable for use on lawn mowers, trash containers, toy wagons and other similar devices. The Improved Wheel is formed in a two step manufacturing process. In the first step, a quantity of hubs are injection molded from a thermoplastic or a thermoset plastic. Two opposing interlocking hubs are used in the manufacture of each wheel. The hubs provide additional strength and improved wear characteristics to the wheel. In the second manufacturing step, a pair of opposing interlocking hubs are placed in the open mold of a conventional blow molding machine. The parison, which is preferably an elastomer, is then extruded between the two open halves of the mold. The two halves of the mold close and capture the parison between the two interlocking hubs in the mold cavity forming a web which radiates from the central bore of the hubs. The remainder of the parison is inflated to form a tube around the exterior of the hubs. ## Claims ### Claim 1 A wheel manufactured in part by conventional blow molding techniques in which a parison is extruded between two opposing halves of an open mold, comprising: a. first and second opposing disc-shaped interfitting hubs, each having an aligned central bore; b. a web formed from the parison and radiating from said central bore, said web captured between said first and second opposing disc-shaped interfitting hubs; c. said first hub having an interior and exterior face, said interior face formed into 1) a plurality of protruding locking lugs, and 2) a plurality of recessed channels, said lugs and said channels contacting said web; d. said second hub having an interior and exterior face, said interior face formed into 1) a plurality of recessed channels sized and arranged to mate with said protruding lugs in said opposing first hub, and 2) a plurality of protruding locking lugs sized and arranged to mate with said channels in said opposing first hub, said lugs and said channels contacting said web; and e. a tube formed around the outer circumference of said web, said tube and said web being formed from the parison. ### Claim 2 (depends on 1) The wheel of claim 1 wherein: a. said first hub forms a shoulder and a sidewall about its outer circumference, said shoulder and said sidewall having an interior and an exterior face; and b. said second opposing hub forms an opposing shoulder and an opposing sidewall about its outer circumference, said opposing shoulder and said opposing sidewall having an interior and an exterior face; and c. said interior faces of said shoulders and said sidewalls contacting and supporting portions of said tube. ### Claim 3 (depends on 2) The wheel of claim 2 wherein: a. said first hub defines a recess in said interior face, said recess surrounding said central bore, and b. said second opposing hub defines an opposing recess in said interior face, said opposing recess surrounding said central bore, and c. said recesses contact and capture a portion of said parison to strengthen said wheel. ### Claim 4 (depends on 1) The wheel of claim 1 wherein said first and said second opposing disc-shaped interlocking hubs are formed from high density polyethylene (HDPE). ### Claim 5 (depends on 4) The wheel of claim 4 wherein said parison is formed from an elastomer. ### Claim 6 (depends on 5) The wheel of claim 5 wherein said elastomer is Santoprene.RTM.. ### Claim 7 A method for manufacturing an improved wheel comprising the following steps: a. injection molding a first interfitting hub; b. injection molding a second opposing interfitting hub; c. placing said first interfitting hub in one half of an open mold in a conventional blow molding machine; d. placing said second opposing interfitting hub in the opposite half of said open mold in a conventional blow molding machine; e. extruding a tubular parison between said halves of said open mold; f. closing said halves of said mold and capturing said parison between said first interfitting hub and said opposing interfitting hub; g. inflating said parison to create a circumferential tube about said first and said second interfitting hubs; and h. opening said mold and ejecting the improved wheel and flashing from said open mold. ### Claim 8 (depends on 7) The method of claim 7 wherein said first and said second opposing disc-shaped interfitting hubs are formed from high density polyethylene (HDPE). ### Claim 9 (depends on 8) The method of claim 8 wherein said parison is formed from an elastomer. ### Claim 10 (depends on 9) The method of claim 9 wherein said elastomer is Santoprene.RTM.. ### Claim 11 A wheel manufactured in part by conventional blow molding techniques in which a parison is extruded between two opposing halves of an open mold, comprising: a. a first circular injection molded disc having an interior and exterior face and a central bore surrounded by a recess, said bore aligned perpendicular to the axis of said disc; b. a second opposing circular injection molded disc having an interior and exterior face and a central bore surrounded by a recess, said bore of said first disc aligned with said bore of said second opposing disc; c. a web formed from the parison and captured between said first and said second opposing discs; d. a tube formed around the outer circumference of said web, said tube and said web being formed from the parison; e. a plurality of locking lugs extending from said interior face of said first disc and a plurality of recessed channels defined by the spaces between said lugs; and f. a plurality of opposing locking lugs extending from said interior face of said second opposing disc and a plurality of opposing recessed channels defined by the spaces between said opposing locking lugs, said locking lugs of said first disc engaging said opposing recessed channels in said second opposing disc and said opposing locking lugs of said second disengaging said recessed channels in said first disc to interlock said disc with said tube. ### Claim 12 (depends on 11) The wheel of claim 11 wherein said recesses retain a portion of said parison to strengthen said wheel. ### Claim 13 (depends on 12) The wheel of claim 12 further including a first rim formed generally on the outer circumference of said first disc and a second opposing rim formed generally on the outer circumference of said second opposing disc, said rims supporting said tube. ### Claim 14 (depends on 13) The wheel of claim 13 wherein said first and said second opposing disc-shaped interfitting hubs are formed from high density polyethylene (HDPE). ### Claim 15 (depends on 14) The wheel of claim 14 wherein said web and said tube are formed from an elastomer. ### Claim 16 (depends on 15) The wheel of claim 15 wherein said elastomer is Santoprene.RTM..