FIELD OF INVENTION
This invention relates to the design of cross rib structure to
eliminate sink mark from the mounting part. This invention leads
to elimination of sink mark from the exposed surface of the
mounting part of vehicle for example.
BACKGROUND/PRIOR ART
Cross rib structure is provided with a vehicle part for mating with
another part of vehicle.
Currently available design of cross rib structure comprises a
plurality of cross ribs (R) in a line as shown in fig. 1 which is
mounted on a vehicle part. This provision leads to more
accumulation of material around the junction of all ribs (J) from all
cross ribs during molding process followed by cooling of the
accumulated material only from four corners (as shown in fig. 2)
which makes cooling ineffective. This in turn results in increase in
the local area thickness of mounting part thereby causing sink
marks on exposed surface (A surface) of the mounting part.
The above situation demands increase in basic wall thickness of
mounting part in order to avoid sink marks, which leads to
increase in weight thereby adding to its cost.
To obviate the aforesaid problem a core (C) can be provided at the
intersection (junction) of ribs as shown in fig. 3. So that the ribs (R)
can be connected to boss area around the core.
However coring at rib intersections requires more space to
accommodate the cross rib structure on the mounting part. The
bulky structure leads to consumption of more material, which
results in more cost.
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In view of the above, present invention has been proposed which
discloses cross rib structure to eliminate sink mark from the
mounting part of vehicle.
OBJECTS OF THE INVENTION
Primary object of the present invention is to provide cross rib
structure to eliminate sink mark from the mounting part.
Another object of the present invention is to provide cross rib
structure to eliminate sink mark from the mounting part which
overcomes disadvantages associated with the prior art.
Still another object of the present invention is to provide cross rib
structure to eliminate sink mark from the mounting part which
results in low accumulation of material in the local area of
mounting part and better rate of cooling of material.
SUMMARY OF THE INVENTION
According to this invention, there is provided cross rib structure to
eliminate sink mark from the mounting part comprising a plurality
of junctions of atleast two ribs constituting multiple offset ribs.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more
apparent from the ensuing description when read in conjunction
with the accompanying drawings of exemplary embodiments of
invention and wherein:
FIG. 1 shows: Top view of conventional cross rib structure;
FIG. 2 shows: Cooling direction in known cross rib structure;
FIG.3 shows: Conventional cross rib structure with a core;
FIG.4 shows: An embodiment of cross rib structure of present
invention;
FIG.5 shows: Cooling direction in novel cross rib structure in
accordance with present invention.
FIG. 6 shows: Another embodiment of cross rib structure of
invention.
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE
TO THE ACCOMPANYING DRAWINGS
The present invention relies on a concept according to which a
multitude of junctions of atleast two ribs are provided maintaining
a gapthere between so as to form a cross rib structure having offset
ribs which can obviate the problems encountered in currently
existing cross rib structure.
The invention is directed to a novel cross rib type structure. In this
regard reference may be made to fig. 4, wherein the cross rib
structure is having a plurality of offset ribs. In this structure,
atleast two ribs intersect at a point constituting first junction (Ji).
Similarly another pair of ribs intersect at a point constituting
second junction (Ja) with a gap from the first junction (Ji). Thus
the material accumulation occurs from only two ribs side (Si, 82)
and (S3, S4) around the junction (Ji, J2) respectively in contrast to
accumulation of more m.aterial from all ribs side as already
discussed with reference to fig. 1. This leads to low accumulation
of materialin the local area of mounting part, which finally results
in removal of sink mark from the visible surface of the same.
Thus the cross rib structure comprising a plurality of ribs, wherein
junction (Ji) of atleast two ribs is located at a distance (D) from
another junction (J2) of another atleast two ribs.
Factors influencing distance (D) are given hereinbelow:
- Fillet radius between rib and mounting part
- Thickness of rib.
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As best seen in fig. 5 cooling for the accumulated material occurs
from multiple directions (Di-De) which is more in number as
compared to prior art which can be clearly observed from^ the fig. 5
and fig. 2. Thus less accumulated m.aterial withimproved cooling of
the same reduces the tendency of any sink marks on the outer
surface of mounting part exposed to user.
According to another embodiment of invention, there can be three
or more number of intersections of ribs.
The cross rib type structure of instant invention can be put to
multiple uses that it can be used as guide, locator etc. without
restricting its scope to the same.
The cross rib can be used as locator in injection molding parts to
control the part in its designed position, which can also be used to
guide the part during assembly with another mating part of
vehicle.
The cross rib can be made of material such as any polymer of
plastic. However, other suitable materials are also applicable to the
invention.
Advantageous features over prior art
- Low accumulation of material in the local area of mounting
part i.e. around the junction during injection molding
process.
- Better rate of cooling due to availability of more direct
cooling surfaces around the accumulated material.
- No sink marks on visible surface of mounting part.
- No increase in weight and cost as compared to known art.
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It is to be noted that the present invention is susceptible to
modifications, adaptations and changes by those skilled in the art.
Such variant embodiments employing the concepts and features of
this invention are intended to be within the scope of the present
invention, which is further set forth under the following claims:-

WE CLAIM:

1. Cross rib structure to eliminate sink mark from the
mounting part comprising a plurality of junctions of atleast
two ribs constituting multiple offset ribs.
2. Cross rib structure to eliminate sink mark from the
mounting part as claimed in claim 1 wherein said junctions
of atleast two ribs are located at a distance from each other.
3. Cross rib structure to eliminate sink mark from the
mounting part as claimed in claim 1 or 2 wherein the
distance relies on factors of fillet radius between the rib and
mounting part and thickness of rib.
4. Cross rib structure to eliminate sink mark from the
mounting part as claimed in any of the preceding claims
which can be used as guide to guide the part during
assembly and locator to control the part in its designed
position.
5. Cross rib structure to eliminate sink mark from the
mounting part as claimed in any of the preceding claims is
associated with the advantageous features such as herein
described.
6. Cross rib structure to eliminate sink mark from the
mounting part as claimed in any of the preceding claims
which can be used in vehicle.

7. Cross rib structure to eliminate sink mark from the
mounting part substantially as herein described with
reference to the accompanying drawings.