Note: Descriptions are shown in the official language in which they were submitted.
CA 02818762 2013-06-14
REINFORCED BLOW MOULDED VEHICLE RUNNING BOARD
AND METHOD OF MAKING SAME
RELATED APPLICATIONS
This application claims the benefit of 35 USC 119(e) to United States
Provisional
Patent Application Serial No. 61/653576, filed May 31, 2012.
SCOPE OF THE INVENTION
The present invention relates to reinforced blow moulded articles, more
preferably blow moulded vehicle parts such as running boards, seat backs, load
floors and
bumper beams which are provided with one or more internal stiffening or
reinforcing ribs
to provide structural reinforcement. More preferably the articles are provided
with one or
more fiber-reinforced plastic stiffening ribs formed having a composition
which is
complementary to that of a blow moulded plastic overmould body to facilitate
the reuse
and recycling of waste flash and/or rejected articles by regrinding and re-
melt, as part of a
thermoplastic base resin used overmould production.
BACKGROUND OF THE INVENTION
The manufacture of blow moulded articles for use as vehicle parts is known. In
the case of larger vehicle parts which are provided for either structural
applications, or
which, as a result of design requirements, are required to provide bend or
deformation
resistance, conventionally one or more rib-like reinforcing webs are moulded
directly into
the part sidewall.
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Figure 1 shows a cutaway perspective bottom view of a prior art blow moulded
running board 10 produced in accordance with conventional manufacturing
processes.
The running board 10 is formed by blow moulding a thermoplastic resin parison
in a
mould having a desired overall elongated shape. After moulding, the running
board 10 is
formed having a generally hollow interior 100 which is delineated by a moulded
resin
sidewall 12, and which defines generally parallel spaced and longitudinally
extending
upper tread and bottom surfaces 18,20 which are joined to each other along the
respective front and rear sides by forward and rear side webs 22,24.
As shown in Figure 1, the bottom surface 20 of the running board 10 is adapted
for mounting at its end and mid-portions, against three or more L-shaped steel
brackets
(brackets 28a,28b shown), which in turn are secured directly to a side of a
vehicle frame
(not shown). To facilitate proper positioning and mounting, the bottom surface
20 may
include a series of moulded spaced recesses 30. Each recess 30 is moulded
directly into
the sidewall 12 and is sized for alignment and juxtaposed engagement with an
associated
bracket 28, respectively.
The sidewall 12 further defines a series of longitudinally aligned V-shaped
reinforcing webs 32 formed in the bottom surface 20, and which extend between
the
recesses 30. As shown in the cutaway view, the reinforcing webs 32 are formed
with an
upwardly tapering V-shape and terminate at an uppermost bight immediately
adjacent to
the underside 18a of the upper tread surface 18. The taper angle of the V-
shape of the
reinforcing webs 32 is chosen to prevent the running board 10 from binding
within the
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mould following its formation, and facilitate its removal therefrom after
moulding
operation.
The inventors have appreciated that conventional prior art running boards 10
suffer various disadvantageous. In particular, as a result of their angular
geometry, the
V-shaped reinforcing webs 32 achieve less structural reinforcement than, for
example, a
planar I beam or vertical-web reinforcement designs. In addition, as a result
of mould
limitations, it is not possible to provide reinforcing structures between the
running board
upper tread surface 18 and the moulded bracket recesses 30. As a result,
conventional
blow moulded running boards 10 suffer the disadvantage that in their design,
unreinforced weakness points exist which could result in premature deformation
and/or
part failure in the event of loading.
SUMMARY OF THE INVENTION
To at least partially overcome some of the difficulties associated with prior
art
designs, the present invention provides a structurally reinforced blow moulded
article or
assembly. The assembly includes an overmould member or body which is formed
from a
glass fiber or graphite reinforced thermoplastic base resin mixture, and which
is bonded
to and/or at least partially encapsulates one or more preformed internal
stiffening or
reinforcing inserts or ribs. The reinforcing inserts or ribs (hereinafter
collectively
referred to as ribs) are preferably at least partially encapsulated by and/or
melt fused to
the overmould member by blow moulding in an orientation selected to at least
partially
carry load and/or impact forces thereon.
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The base resin mixture used in the formation of the overmould member
preferably
comprises between about 10% to 40% by weight short glass, polycarbonate and/or
graphite fibers having a length less than about 15 cm, and about 60% to about
90% by
weight thermoplastic resin. To facilitate the recycling and reuse of not only
waste flash,
but more preferably also damaged or defective finished parts, the reinforcing
ribs
preferably comprise between about 30 to 70% by weight long glass or graphite
fibers
having longitudinal length greater than about 25 cm, preferably greater than
50 cm, and
most preferably which extend the entire longitudinal rib length; and about 30%
by weight
to 70% by weight of thermoplastic bonding resin.
The applicant has appreciated that with the foregoing overmould and rib
compositions, both waste flash, as well as any defective ribs and/or finished
products
advantageously may be reground and blended for re-use as part of thermoplastic
base
resin/short fiber mixture in the blow moulding of subsequent overmould parts,
minimizing manufacturing waste. Most preferably, the overmould body is formed
by
blow moulding a resin mixture comprising between about 20% to 30% by weight
short
glass fibers and 70% to 80% by weight of a thermoplastic base resin selected
from
polyethylene, polypropylene, and/or acrylonitrile butadiene styrene (ABS).
Other
thermoplastics and/or thermoplastic resins may however be used, depending upon
the
completed article and/or its intended application. .
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The short glass fibers preferably have a longitudinal length selected at less
than
about 10 cm, preferably less than about 1 cm, and most preferably less than
about 0.5 cm.
Although not essential, in a preferred construction the bonding resin used in
the
formation of the rib is the same as, or complimentary to, the base resin used
in the
formation of the overmould body.
It is envisioned that the reinforced assembly may be used for the manufacture
of a
variety of different types of blow moulded articles. In one preferred
application, the
reinforced assembly is produced as a vehicle part, and which may include by
way of non-
limiting example a vehicle running board, a seat back, a vehicle load floor,
and/or a
vehicle bumper beam. The assembly is, however, applicable to the manufacture
of other
vehicle parts and classes of reinforced blow moulded articles.
Although not essential, in one preferred configuration, the reinforcing rib is
provided with a generally I-beam shaped profile, having a pair of spaced
lateral flanges
joined by a longitudinally extending connecting web. The rib preferably has a
lateral
width of between about 0.5 to 1 cm and is provided with an upper edge which
follows the
general contour of a forward or top surface of the overmoulded body to be
reinforced.
Most preferably, the rib has a height selected to extend forwardly in a
general
perpendicular orientation from a rear surface of the overmould body to
engagedly support
the underside of the forward surface.
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Other rib profiles, however, may also be used including those with either a
simple
rectangular or L-shaped profiles.
In a most simplified construction the reinforcing rib may be manufactured
having
a homogeneous internal composition. In an= alternate construction, to
facilitate melt
bonding with the overmould body, the reinforcing rib may be formed having an
compound structure in which the connecting web is formed substantially
entirely of
thermoplastic resin, and one or both rib flanges are formed having long glass
fiber
reinforced cores which are at least partially coated with an outer
thermoplastic resin
layer.
Optionally, the stiffening rib may be further provided with a series of
longitudinally spaced radial projections, webs, bosses, suitable barbs or
other suitable
fingers (hereinafter collectively referred to as fingers). The fingers have a
size selected to
facilitate their preferential melting during overmoulding operations to
enhance the
anchoring and positioning of the rib and its melt attachment to the overmould
body.
Accordingly, in one aspect the present invention resides in a structurally
reinforced blow moulded assembly, the assembly comprising, an overmould
member,
said overmould member having sidewall defining a hollow interior, a forward
support
surface and rear surface generally parallel to and spaced from the forward
support
surface, the overmould member 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
base resin, wherein said short glass fibers having a longitudinal length
selected at less
than about 10 cm, and preferably less than about 1 cm, at least one
longitudinally
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elongated reinforcing rib insert, said rib insert being partially encapsulated
by said
sidewall including, a forward flange member provided for bearing contact with
an
interior side of said forward support surface, a rearward flange member spaced
from the
forward flange member and providing a rearward bearing surface generally
coplanar with
said rear surface, and a longitudinal extending connecting web joining the
forward flange
to the rearward flange, each of the forward and rearward flanges comprising
about 40%
by weight to about 70% by weight long glass fibers, and about 30% by weight to
about
60% by weight of a bonding resin, wherein said long glass fibers have a
longitudinal
length greater than about 25 cm, and preferably a length corresponding to a
longitudinal
length of said rib.
In another aspect, the present invention resides in a structurally reinforced
vehicle
part, the vehicle part comprising, an overmould body having sidewall defining
a hollow
interior, a forward surface and rear surface spaced from the forward surface,
the
overmould body 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 having a longitudinal length selected at less than about 10
cm, a
longitudinally elongated reinforcing rib reinforcing said forward surface
against a
rearward load force, the reinforcing rib at least partially encapsulated by
said sidewall
and including, a longitudinally extending forward flange member in
substantially bearing
contact with a portion of said sidewall defining said forward surface, a
longitudinally
extending rearward flange member spaced from the forward flange member and
having a
rearward bearing surface disposed in a generally coplanar orientation with
said rear
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surface, and a longitudinal extending connecting web joining the forward
flange to the
rearward flange, the reinforcing rib comprising about 30% by weight to about
70% by
weight, and preferably upto 60% by weight long glass fibers having a
longitudinal length
greater than about 50 cm, and preferably a length corresponding to a
longitudinal length
of said rib, and about 30% by weight to about 70% by weight, and preferably
40% to
70% by weight of said thermoplastic resin.
in a further aspect, the present invention reside in a vehicle running board
comprising: an overmould composite plastic step, said step having a sidewall
defining a
hollow interior portion, an upper support surface for supporting a user
thereon, and a
lower mounting surface spaced from the upper support surface, the step
comprising
between about 10% by weight short glass fibers having a longitudinal length
selected at
less than about 15 cm, and preferably less than about 1 cm, and about 70% by
weight of a
resin selected from the group consisting of ABS, polyethylene, and
polypropylene, at
least one reinforcing rib, said rib having an elongated longitudinally length
and
comprising, an upper flange member, a lower flange member, and a connecting
web
extending between and joining said upper and lower flange members, each of
said upper
and lower flange members comprising between about 40% by weight to 70% by
weight
long glass fibers having a longitudinal length greater than about 50 cm and
preferably
greater than about 100 cm, and about 30% by weight to about 60% by weight of
said
resin, said upper flange member and connecting web being substantially
encapsulated
within and retained by said sidewall, with an upper portion of said upper
flange member
disposed substantially adjacent to said upper support surface and a bottom
portion of said
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lower flange member in substantially co-planar alignment with an adjacent
portion of
said rear surface, whereby load forces on said forward support surface are at
least
partially carried by said rib.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference may be had to the enclosed drawings together with the following
detailed description, in which:
Figure 1 shows a partial cutaway perspective bottom view of a conventional
blow
moulded vehicle running board in accordance with the prior art;
Figure 2 illustrates a perspective view of a blow moulded vehicle running
board
in accordance with a first aspect of the invention;
Figure 3 shows a partially cut-away perspective bottom view of the running
board
of Figure 2 taken along lines 3-3', showing the positioning of a reinforcing
rib therein;
Figure 4 shows a partial perspective view of the reinforcing rib used in the
running board of Figure 2 in accordance with a first embodiment of the
invention;
Figure 5 shows a cross-sectional view of a reinforcing rib for use in the
running
board of Figure 2 in accordance with a second embodiment of the invention;
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Figure 6 shows schematically a moulding die used in the pultrusion moulding of
the reinforcing rib shown in Figure 5;
Figures 7 to 9 illustrate schematically the positioning of the reinforcing rib
of
Figure 5 in a blow moulding die during blow moulding encapsulation and fusion
of the
overmould running board sidewall thereabout;
Figure 10 provides a partial cross-sectional view of the moulding die platen
used
in the blow moulding die shown in Figure 7, illustrating the securement of the
reinforcing rib therein, prior to the formation of the overmould sidewall; and
Figure 11 shows a cross-sectional view of the blow mould running board
illustrating the partial and encapsulation of the reinforcing rib by the
overmould sidewall,
= immediately following blow moulding operation.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Reference may be had to Figure 2 which illustrates a thermoplastic glass fiber
composite vehicle running board 50 which is manufactured in accordance with a
most
preferred aspect of the invention. The vehicle running board 50 is provided
for mounting
against a pair of conventional L-shaped steel mounting brackets 28a,28b for
securement
along the side of a vehicle (not shown). Depending on the application, the
running board
50 has a typical longitudinal length selected at between about 1 and 2 meters,
and a
lateral step width of between about 10 and 20 cm. As will be described, the
vehicle
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running board 50 is formed having internal structural reinforcement which
provides the
running board 50 with sufficient structural integrity to enable its securement
to the
vehicle using only the single pair of mounting brackets 28a,28b in supporting
the running
board 50 towards each respective longitudinal end, thereby reducing the
running board
installation time.
As shown best in Figure 3 the running board 50 has a generally hollow open
interior 100 and is formed having a binary construction consisting of a fiber
reinforced
thermoplastic sidewall 52 which is reinforced by a longitudinally extending
fiber
reinforced thermoplastic reinforcing rib 54. As will be described to
manufacture the
running board 50, the sidewall 52 is formed as a blow moulded overmould which
partially encapsulates., and is melt bonded to the reinforcing rib 54 for
enhanced structural
rigidity. As shown best in Figure 3, the sidewall 52 defines the overall
running board
profile. In this regard, the sidewall 52 delineates an upper surface 60 which
includes the
running board upper tread surface 62 for supporting a user thereon, a
generally planar
bottom surface 64 which is spaced from the tread surface 62, and forward and
rearward
connecting webs, 66,68 which merge with to join the upper and bottom surfaces
60,64.
As shown best in Figures 3 and 4, the bottom surface 64 is formed having a
pair of
moulded recesses 72a,72b which are each spaced towards a respective running
board end
74a,74b. The recesses 72a,72b are sized to receive therein the associated
mounting
bracket 28 in the securement of the running board 50 along the side of the
vehicle.
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Figure 3 shows best the stiffening rib 54 as positioned to carry and transmit
load
forces on the sidewall 52 to the mounting brackets 28a,28b. As will be
described, the rib
54 is moulded directly into the running board 50 itself, so as to extend in a
generally
vertical orientation along its longitudinal mid-axis.
The sidewall 52 and reinforcing rib 54 are both formed from complimentary
fiber/resin compositions which are selected to enable waste flash, defective
reinforcing
ribs 52 and/or the entirety of any blemished or defective running boards 50 to
be recycled
for subsequent use in the manufacture of other thermoplastic blow moulded
articles.
Most preferably, the sidewall 52 is formed from a fiber reinforced
thermoplastic base
resin mixture which contains from about 10% by weight to about 30% by weight
short
glass fibers, and about 70% by weight to about 90% by weight of a base resin
of ABS,
polyethylene polypropylene or mixtures thereof. To facilitate blow moulding,
the short
glass graphite and/or polycarbonate fibers having a length of less than 1 cm,
and more
preferably less than about 0.5 cm.
The reinforcing rib 54 is formed having an overall composition which includes
upto 50% by weight long glass graphite and/or polycarbonate fibers, and at
least 50% by
weight of a thermoplastic bonding resin. Although not essential, the long
glass fibers are
preferably selected from glass fibers which are comingled with a bonding
resin, such as
ABS, polyethylene, polypropylene or mixtures thereof, and which are heat fused
in a
generally parallel orientation. The long glass fibers 122 have a longitudinal
length of
preferably at least about 25 cm, and more preferably extend substantially the
entire
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longitudinal length of the rib 54. For maximum recyclability, the bonding
resin is most
preferably is chosen the same as the base resin used in the formation of the
sidewall 52
The applicant has appreciated that providing the reinforcing rib 54 having the
aforementioned composition advantageously allows for simplified recycling and
repurposing of defective or blemished ribs 54 and running boards 50. In
particular,
blemished or defective running boards 50 may be reground, and the reground
material
thereafter re-mixed into the base resin mixture for use in the blow moulding
of sidewalls
in the manufacture of a subsequent running board 50, and/or in the manufacture
of further
articles and parts.
Figure 4 illustrates a partial perspective view of the reinforcing rib 54 in
accordance with a first embodiment of the invention. The reinforcing rib 54 is
provided
with an elongated longitudinal length which extends substantially the
longitudinal length
of the running board 50. The rib 54 is provided with a pair of laterally
extending spaced
upper and lower flanges 76,78. The flanges 76 extend the longitudinal length
of the rib
54 and are joined by a connecting web 80. The vertical height between the
flanges 76,78
is selected such that following the encapsulation of the rib 54 by the
sidewall 52, any load
forces on the upper tread surface 62 along the entire length of the running
board 50 are
transmitted to and carried by the rib 54 onto the mounting brackets 28.
In the embodiment shown, the upper and lower flanges 76,78 are provided with a
partially rounded cross-sectional profile. The applicant has appreciated that
the rounded
flange shape of the flanges 76,78 advantageously facilitate pultrusion
moulding of the
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reinforcing rib 54. Most preferably, the upper flange 76 has a generally round
cross-
sectional profile having an approximate radially diameter selected at between
about 1 and
2 cm. The lower flange 78 is formed having a flattened triangular cross-
sectional profile.
The lower flange 78 provides the rib 54 with a generally planar bottom 84
having a
lateral width selected at between about 2 and 4 cm for dispensing load forces
thereon, and
which tapers upwardly to merge with the connecting web 80.
In the construction shown, the connecting web 80 has a lateral thickness
selected
at less than about 5 mm, preferably less than about 3 mm, and most preferably
about 1
mm. Depending upon the size of the running board 50, the web 80 is formed
having the
vertical dimension between the flanges 76,78 selected at between about 0.3 and
1.5 cm.
it is to be appreciated, however, that connecting webs of different dimensions
may be
used, depending upon the article of manufacture.
Although not essential, in a most preferred construction the reinforcing rib
54 is
provided having a compound construction in which the upper and lower flanges
76,78
are provided respectively with a long fiber reinforced core, 86,88 which are
each in turn
further encapsulated by an outermost bonding layer 90. Preferably, each of the
long fiber
reinforced cores 86,88 are themselves composed of 40% by weight to about 70%
by
weight of the long glass fibers, and about 30% by weight to about 60% by
weight of the
bonding resin, and wherein the bonding resin is used to effect the melt fusion
of the long
glass fibers to each other in a generally parallel strand orientation.
Although not
essential, preferably the connecting web 80 is formed so as to consist
entirely of bonding
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resin. The bonding layer 90 most preferably is also formed entirely of the
bonding resin,
to better facilitate the partial melt bonding and fusion with the sidewall 52
during
overmoulding.
As shown best in Figure 7, the reinforcing rib 54 is provided with a pair of
cutouts
94a,94b. Each cutout 94 is sized and spaced for alignment with a corresponding
recess
72a,72b. The cutouts 94 have a dimension selected such that in final assembly,
the upper
flange 76 of the rib 54 locates immediately adjacent to the underside of the
upper tread
surface 62 and the bottom 84 of the lower flange 78 in a substantially
coplanar alignment
with the adjacent portions of the bottom surface 64. So positioned, the upper
flange 76
and connecting web 80 provides reinforcement to the running board 50 at each
of the
recesses 72a,72b. The extension of the cutout portions of the rib 54 over the
recesses
72a,72b thus minimizes any points of weakness along the longitudinal length of
the
running board 50. Once vertically positioned, the stiffening rib 54 thus
provides added
structural support by transmitting load forces placed on the tread surface 62
directly and
evenly through the running board 54, to the bottom surface 84.
Reference may be had to Figure 5 which illustrates a pultrusion formed
connecting rib 54 for use with the running board 50 in accordance with a
further
embodiment of the invention, and wherein like numerals are used to identify
like
components. In the rib 54 shown in Figure 5, the portion of the bonding layer
90 in which
defines the outermost perimeter of the upper flange 76 and connecting web 80
is further
provided with a series of longitudinally extending melt fingers 96. The melt
fingers 96
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extend radially outwardly a distance of between about 0.5 and 1 mm, and have a
thickness selected to preferentially melt and heat fuse with the sidewall 52
during
overmoulding operation. The applicant has appreciated that the provision of
the melt
fingers 96 advantageously provide enhanced melt bonding between the
reinforcing rib 54
and sidewall 52, to more securely fix the rib 54 against movement relative
thereto.
Figure 6 shows schematically the manufacture of the reinforcing rib 54 shown
in
Figure 5 by pultrusion moulding in accordance with a preferred method. Figure
6
illustrates a pultrusion mould 110 which includes a pair of primary mould
cavities
112,114 which are used to preform the long fiber reinforced cores 86,88
respectively, and
a capstock feed inlet 116 which provides fluid communication with the
secondary mould
cavity 120 which is downstream from the primary cavities 112,114, and which is
used
from the finished rib profile. The capstock feed inlet 116 is used for the
melt injection of
bonding resin to form the outer bonding layer 90 and connecting web 80 about
the heat
bonded glass fiber cores 86,88.
As shown in Figure 6, with the pultrusion mould 110, initially long glass
fibers
which have been co-mingled with the bonding resin are drawn into the primary
mould
cavities 112,114. Initially, parallel strands of thermoplastic co-mingled
glass fibers are
compacted and heated in each mould cavity 112,114 the mould at a temperature
slightly
above the resin decomposition temperature, to fuse the fibers and form
reinforced cores
86,88 having the desired profile.
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After partial melt fusing of the co-mingled fibers as the reinforced cores
86,88,
the formed cores 86,88 drawn into the secondary mould cavity 120 where the
bonding
resin is melt injected via the capstock feed inlet 116 to form the bonding
layer 90,
connecting web 80 and melt fingers 96.
In one simplified form of manufacture, the stiffening rib 54 is formed by
pultrusion by drawing polypropylene glass spooled threads through the
pultrusion mould
110, while impregnating with a structural plastic bonding resin to form a
finished rib
blank 54'. The blank 54' is then cut to the desired longitudinal rib length,
having regard
to the length of the finished running board 50, and the cutouts 94a,94b are
formed in a
single stamping. The resulting formed , rib 54 is provided with melt fused
glass fibers
.which have an axially length which extend the entire length of the rib 54,
and which have
a continuous length selected at between about 200 cm to 250 cm.
While in a preferred method of manufacture, the elongated glass fibers are
drawn
through the mould 110 so as to heat fuse to each other in a generally parallel
arrangement, it is to be appreciated that in other constructions, the long
glass fibers 122
may be pre-wound, braided, and/or twisted prior to being drawn into the mould
110.
Similarly, while pultrusion provides various advantages in manufacture, it is
to be
appreciated that in alternate modes of manufacture, the rib 54 could also be
formed by
compression or injection moulding.
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In a most preferred sidewall construction, the upper surface 60, bottom
surface 64
and side webs 66,68 are integrally formed from a plastic/short fiber base
resin parison
mixture, consisting of polypropylene or ABS, and 10 to 30% glass fibers which
have an
average length of between about 0.1 cm and 0.5 cm. It is envisioned that the
base resin
mixture used to form the running board sidewall 52 includes both virgin and re-
ground
components including waste flash, as well as reground rejected pieces. The
sidewall 52
is formed as an overmould body which is blow moulded over a preformed
reinforcing rib
54 to substantially encapsulate and bond therewith.
Figures 7 to 9 show best a two-part mould 130 used in the final manufacture of
the running board 50 shown in Figure 2. The mould 130 includes bottom and top
mould
platens 132,134. The bottom platen 132 is used to form the running board
bottom surface
64, recesses 72a,72b and part of the connecting webs 66,68. The top platen 134
is used
to form the upper surface 60 including the upper tread surface 62, as well as
part of the
connecting webs 66,68.
Figures 7 and 11 show best, the bottom platen 132 as being provided with a
longitudinally elongated vacuum channel 136. The channel 136 is formed having
a flat
bottom sized to receive therein in juxtaposed contact the bottom 84 of the
reinforcing rib
54. The vacuum channel 136 is further provided with a series of longitudinally
spaced
vacuum manifold apertures 140 which are fluidically coupled by associated
vacuum lines
142 (Figure 10) to a negative pressure source (not shown). The apertures 140
are spaced
along the bottom of the channel 136 at locations selected whereby the
activation of the
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vacuum source effects a sufficient negative pressure to releasably secure a
reinforcing rib
54 to the bottom platen 132, with the bottom 84 of the lower flange 78 in
juxtaposition
within the vacuum channel 136.
To form the running board 50, a preformed reinforcing rib 54 is initially
positioned in the platen 132 in a generally vertical orientation with its
bottom 84
positioned in the vacuum channel 136. The vacuum source is actuated, drawing
air
through the apertures 140 via the associated vacuum lines 142, maintaining the
rib 54 in
the desired orientation during blow moulding operations. With the rib 54 so
secured, the
mould 130 is activated to hot extrude a parison 144 of melted base resin
between the top
and bottom platens 132,134. With the parison 144 hot extruded therebetween,
the platens
132,134 are thereafter move together in the direction of arrows 200 closing
the mould
cavity. The heated parison 144 is thereafter stretched into the desired shape
to form the
sidewall 52 by blow moulding, encapsulating the stiffening rib 54 in the
manner shown in
Figure 11. During stretching of the parison 144, the melt fingers 96 are
contacted and
partially melted and fuse bonded to the blown moulded plastic sidewall 52. The
heat
fusing of the blown plastic sidewall 52 with the melt fingers 96 further
anchors the rib 54
in the desired vertical orientation within the interior of the running board
50.
Because the exposed rib bottom 84 and bottom surface 64 of the formed running
board 50 is substantially flat, the formed part may be easily removed from the
lower
mould bottom platen 132 with minimum concern of die lock.
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Because the formed running board 50 is made entirely with a glass reinforced
plastic structure, any excess flash produced in moulding operations, as well
as waste rib
material or even entire rejected parts may be re-ground and re-melted for use
in
subsequent part manufacture. The current invention thus advantageously
provides a more
economical, waste-resistant manufacturing process.
In another possible construction, the rib 54 may be provided with one or more
through-bores (not shown) in addition to or in place of the melt fingers 96.
Such
through-bores are sized to allow for the penetration of the blow moulded
plastic
therethrough, to facilitate stabilization and anchoring of the rib 54 within
the running
board interior 100.
Although the foregoing description describes the manufacture of a reinforced
blow moulded running board 50 having a single stiffening rib 54, the invention
is not so
limited. It is to be appreciated that the running board 50 could be provided
with multiple
stiffening ribs 54 at lateral and/or longitudinally arranged orientations. In
addition, the
process of the present invention may be used in the manufacture of a variety
of other
types of blow moulded components and article for both vehicle and non-vehicle
applications, with the result that the foregoing detailed description should
not be viewed
as limiting.
While the detailed description describes the rib 54 as having an upper flange
76
with a rounded-cross section profile, and a lower flange 78 having a generally
triangular
CA 02818762 2013-06-14
profile, the invention is not so limited. It is to be appreciated that
depending upon the
application and the load forces to be carried, the reinforcing rib 54 may be
provided with
a number of different profiles. In one alternate, non-limiting embodiment,
both the upper
and lower flanges 76,78 could be provided as generally planar lateral
projections. In an
alternate possible design, the reinforcing rib 54 may be formed having an L-
shaped
profile. Other rib profile designs are also possible will now become apparent.
While the detailed description describes and illustrates various preferred
embodiments, the invention is not so limited. Many modifications and
variations will
now occur to a person skilled in the art. For a definition of the invention,
reference may
be had to the appended claims.
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