Reinforced Blow Moulded Vehicle Running Board and Method of Making Same

Abstract

A structurally reinforced blow moulded assembly includes an overmould body bonded to one or more preformed internal stiffening ribs. The reinforcing r ribs are partially encapsulated by o the overmould body in an orientation selected to carry load a forces thereon. The resin mixture used to form the overmould body comprises 10 % to 40 % by weight short glass having a length less about 15 cm, and 60 % to 90 % by weight thermoplastic resin. To facilitate recycling the reinforcing ribs comprise 30 to 60 % by weight long glass fibers and 40 % to 70 % of thermoplastic bonding resin.

We claim: 
     
         1 . A method of manufacturing a structurally reinforced blow moulded assembly,
 the blow moulded assembly comprising,
 an overmould member having a sidewall, the overmould member comprising between 10% by weight to 30% by weight short glass fibers having a longitudinal length of less than 10 cm, and 70% by weight to 90% by weight of a thermoplastic base resin, and 
 a longitudinally elongated reinforcing rib insert at least partially encapsulated within said sidewall, said reinforcing rib insert having at least one flange member comprising 40% by weight to 70% by weight long glass fibers having a length of greater than 25 cm up to a length corresponding to a longitudinal length of said reinforcing rib insert, and 30% by weight to about 60% by weight of a bonding resin, said method comprising the steps of, 
   drawing said long glass fibers co-mingled with said bonding resin through a pultrusion mould to at least partially heat fuse the co-mingled fibers to form a reinforced rib blank having at least one reinforced core,   cutting the reinforced rib blank to a desired longitudinal length of the reinforcing rib insert,   positioning the reinforcing rib insert at least partially in an overmould mould, and   blow moulding the overmould member over the reinforcing rib insert.   
     
     
         2 . The method as claimed in  claim 1 , wherein the reinforcing rib insert includes a forward said flange member, a rearward said flange member and a longitudinally extending connecting web joining the forward flange member and the rearward flange member, and
 wherein during said drawing step, melt injection moulding additional bonding resin about the melt fused co-mingled fibers to form the connecting web.   
     
     
         3 . The method as claimed in  claim 2 , wherein at least one of the forward flange member, the rearward flange member and the reinforcing web includes a bonding layer and/or one or more longitudinally extending melt fingers, and
 wherein said step of injecting additional said bonding resin comprises melt injection moulding said additional bonding resin about the at least one reinforced core to form said bonding layer and/or melt fingers.   
     
     
         4 . The method of  claim 1 , wherein the step of drawing the long glass fibers comprises drawing spooled polypropylene glass threads through the pultrusion mould. 
     
     
         5 . The method as claimed in  claim 1 , wherein the step of at least partially heat fusing the co-mingled fibers comprises compacting and heating the co-mingled fibers to a temperature about a decomposition temperature of the bonding resin to heat fuse the fibers in a generally parallel arrangement. 
     
     
         6 . The method of  claim 5 , wherein said long glass fibers are twisted, pre-wound and/or braided prior to compacting and heating. 
     
     
         7 . The method as claimed in  claim 1 , wherein the blow moulded assembly comprises a vehicle part selected from the group consisting of a vehicle running board, a vehicle seat back, a vehicle load floor and a vehicle bumper beam, the overmould mould comprising a blow mould having a plurality of mould platens, and said step of positioning the reinforcing rib insert comprises positioning the reinforcing rib insert in a first said mould platen, and
 after positioning the reinforcing rib insert, blow moulding the overmould member.   
     
     
         8 . The method of  claim 7 , wherein said step of blow moulding the overmould member includes,
 melt extruding a parison into the blow mould comprising a short fiber/base resin mixture comprising 10% to 30% by weight said short glass fibers and 70% to 90% by weight said thermoplastic resin, and   blow moulding the parison over the reinforcing rib insert to form the overmould member at least partially melt bonded to the reinforcing rib insert.   
     
     
         9 . The method as claimed in  claim 8  wherein said step of positioning said reinforcing rib insert further comprises securing said reinforcing rib insert in said first mould platen by vacuum suction. 
     
     
         10 . The method as claimed in  claim 8 , wherein the short glass fibers have a longitudinal length selected at less than about 1 cm. 
     
     
         11 . The method as claimed in  claim 8 , wherein the thermoplastic resin comprises polyethylene, polypropylene or ABS. 
     
     
         12 . A method of manufacturing a structurally reinforced blow moulded vehicle part, the vehicle part comprising, an overmould body having a sidewall defining a hollow interior, a forward surface and rear surface spaced from the forward surface, the overmould body further comprising between about 10% by weight to 30% by weight short glass fibers, and about 70% by weight to 90% by weight of a thermoplastic resin, wherein said short glass fibers have a longitudinal length of less than about 10 cm, and
 a longitudinally elongated reinforcing rib reinforcing said forward surface against a rearward load force, the reinforcing rib having a longitudinally extending forward portion, a longitudinally extending rearward flange member having a rearward bearing surface, and a connecting web joining the forward portion to the rearward flange,   said method comprising,
 drawing long glass fibers having a length greater than about 25 cm co-mingled with a bonding resin through a pultrusion mould to melt bond said co-mingled fibers as part of a reinforced rib blank, the reinforced rib blank comprising 40% by weight to 70% by weight of said long glass fibers, and 30% by weight to about 60% by weight of said bonding resin, 
 cutting said reinforcing rib from said reinforcing rib blank, 
 positioning the reinforcing rib at least partially in a blow mould, and 
 blow moulding the overmould member over the reinforcing rib in the blow mould, whereby said reinforcing rib is at least partially encapsulated by said sidewall with the longitudinally extending forward position in substantially bearing contact with at least a portion of said sidewall defining the forward surface, and the rearward bearing surface disposed in a generally coplanar orientation with said rear surface. 
   
     
     
         13 . The method of  claim 12 , wherein during said drawing step, melt injecting additional bonding resin about said melt bonded co-mingled fibers. 
     
     
         14 . The method as claimed in  claim 12 , wherein at least one of the forward portion, the rearward flange member and the connecting web includes a bonding layer and/or one or more longitudinally extending melt fingers, and
 wherein said step of injecting additional bonding resin comprises melt injection moulding said additional bonding resins about bonded generally parallel arranged co-mingled fibers to form said bonding layer and/or melt fingers.   
     
     
         15 . The method of  claim 13 , wherein the step of drawing the long glass fibers comprises drawing spooled polypropylene glass threads impregnated with said bonding resin through the pultrusion mould. 
     
     
         16 . The method as claimed in  claim 12 , wherein the blow mould comprises a plurality of mould platens, and said step of positioning the reinforcing rib comprises securing the reinforcing rib in a first said mould platen under vacuum, and
 thereafter blow moulding the overmould member over the reinforcing rib to at least partially melt bond to the reinforcing rib insert.   
     
     
         17 . The method as claimed in  claim 16 , wherein vehicle part is selected from the group consisting of a vehicle running board, a vehicle seat back, a vehicle load floor and a vehicle bumper beam, and said thermoplastic and said bonding resin are each selected from the group consisting of polypropylene, ABS and polyethylene. 
     
     
         18 . A method of manufacturing a structurally reinforced moulded assembly,
 the moulded assembly comprising,
 an overmould member having a sidewall defining a hollow interior, a forward support surface and a rear surface spaced from the support surface, 
   the overmould member comprising between 10% by weight to 30% by weight short glass fiber having a longitudinal length of less than 10 cm, and 70% by weight to 90% by weight of a thermoplastic base resin,   a longitudinally elongated reinforcing rib insert at least partially encapsulated within said sidewall, said reinforcing rib insert having a forward flange member, a rearward flange member spaced from the forward flange member, and a longitudinal connecting web joining the forward flange member to the rearward flange member,   said method comprising the steps of,   drawing said long glass fibers co-mingled with a bonding resin through a pultrusion mould to effect melt fusing of the co-mingled fibers to form a reinforced rib blank,   said rib blank including said forward flange member, said rearward flange member and said connecting web, wherein at least one of said forward flange member and said rearward flange member comprises 40% by weight to 70% by weight of said long glass fibers, and 30% by weight to 60% by weight of said bonding resin, having at least one reinforced core,   cutting the reinforced rib blank to a finished longitudinal length of the reinforcing rib insert, whereby the long glass fibers of the reinforcing rib insert have a longitudinal length of great than 25 cm up to the finished longitudinal length of the reinforcing rib insert,   positioning the reinforcing rib insert at least partially in an overmould mould, and   blow moulding the overmould member over the reinforcing rib insert, with an interior side of the forward support surface in bearing contact with at least a portion of the forward flange surface.   
     
     
         19 . The method as claimed in  claim 18 , wherein during said drawing step, melt injection moulding an additional amount of bonding resin about the melt fused co-mingled fibers to form the connecting web. 
     
     
         20 . The method as claimed in  claim 19 , wherein the moulded assembly comprises a blow moulded vehicle part selected from the group consisting of a vehicle running board, a vehicle seat back, a vehicle load floor, and a vehicle bumper beam, at least one of the forward flange member, the rearward flange member and the reinforcing web includes a bonding layer and/or one or more longitudinally extending melt fingers, and
 wherein said step of injecting additional said bonding resin comprises melt injection moulding said additional bonding resin about the at least one reinforced core to form said bonding layer and/or melt fingers.   
     
     
         21 . The method of  claim 20 , wherein the step of drawing the long glass fibers comprises drawing spooled polypropylene glass threads through the pultrusion mould. 
     
     
         22 . The method of  claim 19 , wherein said step of moulding the overmould member comprises,
 positioning the reinforcing rib insert in a blow mould,   melt extruding a parison into the blow mould comprising a short fiber/base resin mixture comprising 10% to 30% by weight said short glass fibers and 70% to 90% by weight said thermoplastic resin, and   blow moulding the parison over the reinforcing rib insert to form the overmould member at least partially over and melt bonded to the reinforcing rib insert, with the rearward flange member generally coplanar with the rear surface.   
     
     
         23 . The method as claimed in  claim 22 , further comprises securing said reinforcing rib insert in said blow mould by vacuum suction.