Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
1995-05-02
2001-05-29
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S274000
Reexamination Certificate
active
06238610
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention:
This invention relates to a heat exchanger for a radiator or the like, and more particularly to a tank for a heat exchanger in which a seal member is fixedly secured to a skirt portion of the tank, and a method of producing such a tank. The present invention further relates to an injection mold used for forming a resin seal member of the tank.
2. Description of the Related Art:
A conventional heat exchanger tank is shown in
FIG. 1
, in which a resin is injected into an annular groove
15
of a dovetail-shaped cross-section, formed in a skirt portion
13
of the tank
11
, to mold a seal member
17
which is fixedly secured to the annular groove
15
. Hence, disengagement of the seal member
17
from the tank
17
is highly unlikely.
In such a heat exchanger tank, the annular groove
15
of a dovetail cross-section must be formed on the skirt portion
13
of the tank
11
. However, this shape of the annular groove
15
makes it very difficult to remove the tank
11
from a resin from which the tank
11
is molded.
One known heat exchanger tank-producing method which has solved such a problem is disclosed in Japanese Patent Unexamined Publication No. 3-138116.
Such a heat exchanger tank-producing method produces a tank as shown in
FIG. 2
, in which an annular groove
15
having a rectangular cross-section is formed in an open end surface of an annular skirt portion
13
, which is formed over the entire periphery of an open end of a resin tank
11
. The skirt portion
13
is received in a space formed by molds
18
,
19
and
21
.
An outer side surface
13
a
and an inner side surface
13
b
of the skirt portion
13
are held by molds
21
and
19
, respectively, and the outer side surface
13
a
and the inner side surface
13
b
are urged toward each other by a projection
21
a
formed on the surface of each mold
21
facing the outer surface
13
a
of the skirt portion
13
. Seal resin
23
is injected into the annular groove
15
and a seal-forming space
19
a
which is formed in the mold
19
opposed to the annular groove
15
. The seal resin
23
solidifies, thereby producing the heat exchanger tank as shown in FIG.
1
.
However, in such a conventional heat exchanger tank-producing method, the skirt portion
13
is deformed merely by pressing the projection
21
a
against the outer surface
13
a
. Therefore, it is difficult to deform the skirt portion
13
into a predetermined shape. Furthermore, cracks are likely to develop at the portion of the skirt portion
13
disposed laterally to the bottom surface
15
a
of the annular groove
15
.
That is, the heat exchanger tank
11
is formed of a reinforced resin having glass fibers added to a nylon resin, and the tank has an elongated shape having one open end. Therefore, during molding, the tank is susceptible to twisting as well as deformation due to the expansion of its open end.
For example, the skirt portion
13
of the tank
11
having the outwardly-expanded open end is set on the mold
18
as shown in FIG.
3
. Then the molds
19
and
21
are then moved toward the skirt portion
13
, so that the upper end of the inner surface
13
b
of the skirt portion
13
of the tank
11
is positioned by the mold
19
. In this condition, when the outer surface
13
a
of the skirt portion
13
of the tank
11
is pressed by the projections
21
a
of the molds
21
, the outer surface
13
a
is deformed to a large extent by this pressing.
Since that portion of the skirt portion
13
, defining one side wall of the annular groove
15
having the outer surface
13
a
, has a small thickness, deformation develops at that portion of the skirt portion
13
disposed laterally of the bottom surface
15
a
of the annular groove
15
. Hence, it is likely that a crack may develop at this portion.
In a conventional heat exchanger tank that is produced by conventional methods, bubbles are formed in the resin injection-molded seal member
17
at a position located opposite to an injection gate.
In particular, a seal resin
23
, injected from the injection gate
25
, is divided in opposite directions at this injection gate
25
, and flows toward the gate-opposite position
27
through an annular groove
15
in the tank
11
and a seal-forming space in a mold
19
, as indicated by arrows in FIG.
4
. However, since the temperature of the mold
19
is higher than the temperature of the tank
11
, the fluidity of the seal resin
23
in the seal-forming space
19
a
becomes higher than the fluidity of the seal resin in the annular groove
15
.
As a result, in the vicinity of the gate-opposite position
27
, the seal resin
23
in the seal-forming space
19
a
is closer to the gate-opposite position
27
than is the seal resin
23
in the annular groove
15
, as shown in FIG.
5
A. Hence, immediately before the opposite ends of the seal resin
23
impinge on each other at the gate-opposite position
27
, an air reservoir portion
28
is formed at the bottom surface of the annular groove
15
as shown in FIG.
5
B. Then, when the opposite ends of the seal resin
23
are joined together at the gate-opposite position
27
, bubbles
29
are formed in the seal resin
23
, and also a space
30
in which the seal resin
23
is absent is formed, as shown in FIG.
5
C.
In addition, in the conventional injection mold used for producing a tank, since a runner is formed in a sprue of a mold, it is very difficult to separate the runner from the mold
19
.
SUMMARY OF THE INVENTION
The present invention overcomes the above problems of the conventional tank and tank producing method. Specifically, an object of the present invention is to provide a method of producing a tank for a heat exchanger in which a skirt portion of the tank can be positively deformed into a predetermined shape, and thus, a crack is prevented from developing at the skirt portion.
In the heat exchanger tank-producing method of the present invention, when the mold is pressed against the outer side surface or the inner side surface of the skirt portion, the outer side surface or the inner side surface of the skirt portion is deformed by the projection formed on the mold. The outer side surface or the inner side surface of the skirt portion therefore contacts the guide surface progressively from the side close to the open end surface, and is deformed along the guide surface, so that a bending moment, acting on that portion of the skirt portion disposed laterally of the bottom surface of the annular groove, is reduced. This prevents an undue stress from being applied to that portion of the skirt portion disposed laterally of the bottom surface of the annular groove.
A further object of the present invention is to provide a tank for a heat exchanger in which bubbles are prevented from being formed in that portion of a seal member where opposite ends of a seal resin have impinged on each other.
In the heat exchanger tank of the present invention, a bubble removal protuberance is formed on the portion of the bottom surface of the annular groove to be disposed at the impinging position where the opposite ends of the seal resin, injected from the injection gate, impinge on each other. Therefore, before the opposite ends of the seal resin are completely joined together at the impinging position, air present at the bottom surface of the annular groove impinges on the protuberance, and is discharged to a seal-forming space covering the annular groove.
In the heat exchanger tank of another embodiment of the present invention, a bubble removal notch or hole is formed on the portion of the annular groove portion to be disposed at the impinging position where the opposite ends of the seal resin, injected from the injection gate, impinge on each other. The notch or hole extends from the inner side surface of the annular groove to the outer surface of the skirt portion. Therefore, before the opposite ends of the seal resin are completely joined together at the impinging position, air present at the bottom surface of the annular groove impinges is discharged to t
Kusama Seiichi
Yamazaki Hisarou
Calsonic Kansei Corporation
Ortiz Angela
Sughrue Mion Zinn Macpeak & Seas, PLLC
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