Molding process for manufacturing a molded article

Details Molding process for manufacturing a molded article Molding process for manufacturing a molded article

2000-10-06

2002-01-08

Kuhns, Allan R. (Department: 1732)

Plastic and nonmetallic article shaping or treating: processes

Mechanical shaping or molding to form or reform shaped article

Shaping against forming surface

C164S132000, C264S334000

Reexamination Certificate

active

06337044

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a molding process for manufacturing a molded article, more particularly to a molding process for manufacturing a molded article formed with a channel.
2. Description of the Related Art
Molded articles for decoration, souvenir, stationery and the like are normally provided with channels for various purposes.
FIG. 1
illustrates a letter opener
1
including a blade
11
and a handle
2
with a channel
10
for insertion of the blade
11
.
FIGS. 2
to
4
illustrate how a channel
132
is formed in a molded decoration
14
made of a metal. The decoration
14
is prepared by molding the metal in a mold
12
which includes upper and lower mold halves
120
,
121
confining a mold cavity therebetween. Two pairs of opposite positioning grooves
122
are respectively formed in confronting surfaces of the upper and lower mold halves
120
,
121
at two opposite sides of the mold cavity, and are communicates with the mold cavity. To form the channel
132
in the decoration
14
, a rigid hollow rod
13
is placed in the mold cavity with two opposite ends being placed and positioned in the grooves
122
. Metal in a melted state is then introduced into the mold cavity and is molded over the rod
13
to form a molded part. The two opposite ends of the rod
13
that protrude outwardly from the thus formed molded part are subsequently cut off (see
FIG. 3
) or the rod
13
is completely withdrawn from the thus formed molded part to form the channel
132
in the decoration
14
(see FIG.
4
). When the rod
13
is to be withdrawn from the molded part in the process of forming the channel
132
, the rod
13
can be solid instead of being hollow.
The manufacture of the decoration
14
is disadvantageous in that since a portion of the rod
13
remains in the decoration
14
and since the protruding portions of the rod
13
are cut off and will become waste, the manufacturing cost will be increased and disposal of the waste will be troublesome. Moreover, since the rod
13
is tightly surrounded by the molded part, it is difficult to withdraw the same from the molded part. There is thus a tendency for the molded part and/or the rod
13
to be damaged during the withdrawing action.
The mold
12
described above can only produce a channel having a simple shape, and requires the grooves
122
to be formed in the confronting surfaces of the upper and lower mold halves
120
,
121
. When a channel (indicated as reference number
133
′ in
FIG. 6
) having a complex shape, such as a curved shape or a bent shape, is to be formed in a molded part
14
′, or when a plurality of channels
132
,
132
′,
133
,
133
′ extending in different directions are to be formed in molded parts
14
′,
14
″ (see FIGS.
5
and
6
), a multi-piece mold (i.e. more than two pieces) is required for manufacturing the molded part. As such, the manufacture of the molded part becomes very complex and costly. While the channel
132
,
133
in the molded part
14
′ can be formed by drilling, the drilling process is time consuming and can result in an enormous increase in production cost. Furthermore, it is impossible to form the channel
133
′ of the mold part
14
″ by drilling. In an alternative method, the channels
132
,
132
′,
133
,
133
″ in the molded parts
14
′,
14
″ are formed by separating the molded parts into different pieces. At least two mold pieces are needed to combine with each other by welding or gluing to form each of channels
132
,
132
′
133
,
133
′. However, the welding process or the gluing process is also time consuming, and there is a tendency for the mold parts
14
′,
14
″ to break at locations where the welding or the gluing is applied. Moreover, when two channels in two pieces are connected to form a channel in the assembled piece, and when the channel is to be used for storing liquid, there is a tendency for the liquid to leak at locations where the welding or the gluing is applied.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is to provide a molding process for manufacturing a molded article that is capable of overcoming the aforementioned drawbacks.
According to the present invention, a molding process for manufacturing a molded article comprises the steps of: (a) preparing a mold having a mold cavity that has a shape conforming to that of the molded article, and a positioning groove disposed externally of and in communication with the mold cavity; (b) preparing a flexible tube; (c) placing the tube in the mold cavity and positioning one end of the tube in the positioning groove; (d) closing the mold and introducing a molding raw material into the mold cavity around the tube to form a molded part that encloses a portion of the tube; (e) removing the molded part together with the tube from the mold cavity; and (f) withdrawing the tube from the molded part to form a channel in the molded part.


REFERENCES:
patent: 3233310 (1966-02-01), Corl
patent: 3825647 (1974-07-01), Kirsch
patent: 4003778 (1977-01-01), Phillips
patent: 4093175 (1978-06-01), Putzer et al.
patent: 4352772 (1982-10-01), Bezner
patent: 4436690 (1984-03-01), Davis
patent: 4919608 (1990-04-01), Catalanotti et al.
patent: 4948541 (1990-08-01), Beck

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