Package and article carriers – Vehicle attached – Carrier associated with vehicle roof or trunk lid
Reexamination Certificate
2000-09-28
2002-01-15
Cronin, Stephen K. (Department: 3727)
Package and article carriers
Vehicle attached
Carrier associated with vehicle roof or trunk lid
C224S309000
Reexamination Certificate
active
06338428
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle roof rack formed by coating a core member with synthetic resin using an insert molding technique.
2. Description of Related Art
One type of roof rack installed on top of the roof of passenger cars and other vehicles is often manufactured by an insert molding process. In this process the metal core member of the roof rack is placed in the mold at a specific position and molten resin is then injected to fill the mold cavity and coat at least a specific surface area of the core member with synthetic resin.
By manufacturing the roof rack in this way, the strength and rigidity required in a roof rack is assured by the metal core member while coating all or a particular area of the surface of the core member with synthetic resin reduces the overall weight and improves the appearance of the roof rack. Insert molding also results in an integral molding of the coating resin and core, thereby helping to reduce the number of parts in the complete roof rack assembly, eliminating an additional step of assembling the coating and core, and improving adhesion between the coating and core.
The applicant previously invented a method for inserting and securing the core in the mold during insert molding of this type of roof rack. More specifically, the method the applicant disclosed in Japanese Patent Laid-Open Publication HEI 10-129359 applies to a roof rack assembly in which the core of the rack rail extending longitudinally to the vehicle, and the core of the support bracket for mounting the rail to the vehicle roof, are made of metal. The support bracket cores and the rack rail core are first fastened together, and the support bracket cores are then placed in the mold at a specific position using an intervening insert. The complete core assembly is thus inserted to and secured inside the mold.
Changes in owner preferences and aesthetics have led to various changes in vehicle design and appearance. Not only have these changes affected the roof rack installed on the vehicle roof top, they have also made the structure for installing the roof rack more complex in the pursuit of a vehicle that looks better even with a roof rack installed.
One stylistic change in car design has been to rounded edges and a rounded roof. Installing a roof rack on a rounded roof has meant that the support brackets must be offset noticeably to the outside or inside from the conventional position directly vertically below the rack rail. As shown in
FIG. 40
to
FIG. 42
, this requires a bend in the support bracket metal cores
230
,
240
,
250
at some point along the vertical axis thereof. The top of each support bracket metal core
230
,
240
,
250
is then joined with a pipe-shaped rail core
220
, thus assembling core member
210
so that the mounting bolt
208
affixed to the bottom of each support bracket metal core
230
,
240
,
250
is positioned to the outside, for example, of the axis of the pipe-shaped rail core
220
of the roof rack.
A problem with this design is that because of the high precision required when bending and forming the support bracket metal cores
230
,
240
,
250
, production is time-consuming and it is quite difficult to maintain the required shape and dimensional precision.
It should be noted that the support bracket metal cores
230
,
240
,
250
could be formed in the shape of closed boxes so that molten resin is prevented from filling the inside of the box and the box thus stays hollow. This reduces the amount of resin used and keeps the weight down. The problem with this technique is that it is even more difficult and relatively expensive to produce such box-like metal core members. It is particularly difficult to form the metal core members as closed boxes when a bend is required as described above, and it is therefore difficult in practice to prevent resin from filling the core members and thus keep weight down by controlling the resin amount.
The roof rack rails are also long and relatively slender with the length significantly long in relation to the cross sectional area. It is therefore standard practice to use three support brackets, referred to as the front, center, and rear supports, on each rail. Due to vehicle design considerations, however, the center support is often noticeably offset from the actual center, typically toward the rear support, for example.
The resulting long span between the front support and the center support means that the distance between the fixed points at which the pipe-shaped core
220
is supported is also long. As a result, when molten resin R′ is injected during the insert molding process, resin pressure can cause the long unsupported length of pipe-shaped core
220
between front and center supports to bend and shift in position.
Because it is very difficult to inject and fill resin R′ evenly throughout the mold cavity, forcibly injecting resin to the mold cavity results in an uneven distribution of resin pressure, thus causing the position of pipe-shaped core
220
to shift and the thickness of coated resin layer R′ to become uneven. There are also adverse effects on the bond between coating resin R′ and the surfaces of core members
210
,
230
,
250
. Adhesion to the core member
210
is particularly low where coating resin R′ thickness is thin, and appearance defects such as blistering can occur easily.
It should also be noted that roof rack rails are installed in pairs. Manufacturing would therefore be much more efficient and molding easier if the roof rack rail assemblies could be molded in pairs at the same time in the same mold (using multipart molding). The problem with molding two components in a single mold assembly is that using plural gates to supply resin for each molding (roof rack) complicates mold design and makes it more difficult to control molding conditions.
It would therefore be convenient if a single gate common to both die units could be provided between two parallel roof rack mold sections to supply molten resin simultaneously from this one gate to the pair of roof rack molds.
As will be well understood from
FIGS. 41 and 42
, however, a hood-shaped coating resin layer R′ is formed covering the top of pipe-shaped core
220
in roof rack
201
and descending therefrom to both sides. The distance from the bottom on the right side of coating resin layer R′ up and over the top and back down to the bottom on the left side is thus very long in the direction through the vertical section perpendicular to the long axis of pipe-shaped core
220
. Furthermore, when resin is supplied from only one side of the mold using a single gate and the thickness of coating resin layer R′ is limited to some maximum thickness in order to minimize weight, it is difficult to assure that the molten resin completely fills the mold cavity all the way to the lower end of the resin layer at the farthest point from the runner extend from the gate.
Furthermore, ribs
288
are desirably added to the support brackets for reinforcement due to the length of the roof rack
201
itself and the limited thickness of the coating resin layer R′ forming the outside walls of the finished molding (roof rack
201
). However, if these ribs
288
exceed a particular thickness, appearance defects known as sink marks can occur easily on the surface where the ribs
288
join the coating resin layer R′. It is therefore necessary to limit the thickness of the ribs
288
.
However, if the ribs are too thin, a drop in molten resin filling characteristics in the area of the ribs during injection molding means that tall ribs (ribs with a large surface area) cannot be formed. In practice this means that ribs cannot be formed to the full height of the roof rack
201
, and are thus limited in height as indicated by the double-dot dash lines in
FIGS. 41 and 42
. The problem with such low ribs
288
is that they cannot provide sufficient reinforcement for the coating resin layer R′ (outer walls of the product).
The p
Kawasaki Michiharu
Takemoto Yoshihiro
Cronin Stephen K.
GP Daikyo Corporation
Merchant & Gould P.C.
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