Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Including application of internal fluid pressure to hollow...
Reexamination Certificate
1998-07-13
2002-04-23
McDowell, Suzanne E. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Including application of internal fluid pressure to hollow...
C264S531000, C264S536000, C264S540000, C264S155000, C425S533000, C425S577000
Reexamination Certificate
active
06375891
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a resinous tank in which a through-hole is provided at a side wall portion thereof, and more particularly to a method of manufacturing a resinous tank to which blow molding is applied.
2. Description of the Related Art
As a resinous tank manufactured through blow molding, for example, a washer tank which is applied to a wiper device of a vehicle and contains solutions such as a window washer solution or the like is known.
In this type of washer tank, as shown in
FIG. 36
, a through-hole
82
for supplying water is formed at the side wall portion of a tank
80
. Further, in the vicinity of the through-hole
82
, in general, a pump
84
for supplying water is attached to the tank
80
itself. An inlet
86
of the pump
84
is fit the through-hole
82
via a grommet
88
. In this way, sealability around the through-hole
82
is guaranteed. When the pump
84
is operated, a washer solution within the tank
80
is absorbed by the pump
84
and discharged from an outlet
90
.
As mentioned above, the grommet
88
is interposed between the through-hole
82
of the tank
80
and the inlet
86
of the pump
84
in such a way that the sealability of the through-hole
82
is guaranteed. However, in order to guarantee the sealability, good surface roughness is required at the inner circumferential wall (the surface of the through-hole
82
to which the grommet
88
is adhered) of the through-hole
82
. In other words, when the surface roughness of the inner circumferential wall of the through-hole
82
is poor, the adhesion of the through-hole
82
to the grommet
88
deteriorates. As a result, the sealability becomes poor.
Conventionally, the main body portion (the hollow body) of the tank
80
is molded through blow molding, and thereafter, is machined by tools such as a drill or the like. The through-hole
82
is formed and the surface roughness of the seal surface (the inner circumferential wall portion of the through-hole
82
) is guaranteed. Therefore, the number of manufacturing processes, the time to manufacture the product, and the cost of manufacturing are increased.
As a result, a manufacturing technique has been proposed in which subsequent machining which uses tools such as a drill or the like is not required, and when the tank
80
is molded through blow molding, the through-hole
82
can be also formed (Japanese Patent Application Publication (JP-B) No. 3-76808).
In accordance with the manufacturing technique described in JP-B No. 3-76808, a tool with a blade which forms a cavity is provided further outwardly than the molding surface (the cavity) of the molding die, a parison is expanded and a hollow body is formed, and thereafter, the side wall portion of the hollow body is cut out (punched) so as to form the through-hole
82
. In accordance with this manufacturing technique, after the tank
80
(the hollow body) is molded through blow molding, there is no need to implement subsequent machining which uses tools such as a drill or the like and the tank
80
can be formed at one manufacturing process.
However, in the manufacturing technique described in JP-B No. 3-76808, since the side wall portion of the hollow body is cut out (punched) by the tool with a blade so as to form the through-hole
82
, the inner circumferential wall portion (the seal surface) of the through-hole
82
forms a cut surface. Therefore, the surface roughness of the inner circumferential wall portion (the seal surface) is poor (necessary surface roughness cannot be guaranteed), and as a result, the sealability is likely to be poor. Consequently, the tank
80
which is manufactured in accordance with the manufacturing technique described in JP-B No. 3-76808 cannot be applied to a vehicle washer tank or the like.
SUMMARY OF THE INVENTION
With the aforementioned in view, an object of the present invention is to obtain a method of manufacturing a resinous tank in which the surface roughness of the seal surface of a through-hole can be made good and this can be realized at a low cost without requiring complicated machining.
A first aspect of the present invention is a method of manufacturing a resinous tank having a through-hole provided at a side wall portion of the tank, comprising the steps of: providing a tool with a blade at one of molding dies beforehand such that a portion of the tool protrudes further inwardly than the molding surface of the one of the molding dies, the tool being columnar and the blade being provided at a distal end of the tool; forming a hollow body by expanding a resin parison within the molding die such that the resin parison is pressed against inner wall surfaces of the molding dies and brought into close contact with the outer peripheral wall of the tool, protruding the blade of the tool further inwardly than the thickness of a general portion (a portion not provided the tool) of the pressed resin parison such that the outer peripheral wall of the tool forms an inner wall surface of the through-hole; completing formation of the through-hole by advancing the tool further into the hollow body, and cutting out a portion of the resin parison hollow body which portion corresponds to the blade of the tool; and removing the tool from the hollow body, opening the molding dies, and removing the hollow body in which the through-hole has been formed.
In the method of manufacturing a resinous tank relating to the first aspect of the present invention, the tool is provided at the molding die beforehand such that the portion of the tool protrudes further inwardly than the molding surface of the molding die. Since the resin parison is expanded within the molding dies, the parison is pressed against inner wall surfaces of the molding dies and brought into close contact with the outer peripheral wall of the tool.
In this state, the blade of the tool protrudes further inwardly than the thickness of the general portion of the pressed resin parison such that the outer peripheral wall of the tool forms an inner wall surface of the through-hole. The hollow body is thereby formed.
Next, when the tool is advanced further into the hollow body, the resin parison hollow body which portion corresponds to the blade of the tool is cut out and the through-hole is formed. Further, the tool is removed from the hollow body, the molding dies are opened, and the hollow body is removed in which the through-hole has been formed. Consequently, the resinous tank is manufactured.
In accordance with a method of manufacturing a resinous tank relating to the first aspect of the present invention, the resin parison is expanded within the molding dies and brought into close contact with the outer peripheral wall of the tool. In this way, the through-hole is formed. Namely, because the inner wall surface of the through-hole is not a cut surface and is formed in accordance with the outer peripheral wall of the tool (because the outer peripheral wall of the tool is the inner wall surface of the through-hole), the surface roughness of the inner wall portion (the seal surface) can be good (the necessary surface roughness can be maintained). Accordingly, the sealability of the through-hole can be guaranteed and the tank can be suitably used for, for example, a vehicle washer tank or the like.
A second aspect of the present invention is a method of manufacturing a resinous tank having a through-hole provided at a side wall portion of the tank, comprising the steps of: providing a convex portion at one of molding dies beforehand such that the convex portion protrudes further inwardly than the molding surface of one of the molding dies, the convex portion being cylindrical so as to correspond to a through-hole to be formed; disposing a tool with a blade, the tool being columnar and the blade being provided at the distal end of the tool within the cylindrical convex portion; forming a hollow body by expanding a resin parison within the molding dies such that the resin parison is pressed against the inner wall surfaces
Jinno Kouichi
Natsume Akihiko
Nishikawa Makoto
Asmo Co. Ltd.
McDowell Suzanne E.
Parkhurst & Wendel L.L.P
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