Metal mold for producing a synthetic resin molded product

Details Metal mold for producing a synthetic resin molded product Metal mold for producing a synthetic resin molded product

1998-12-31

2001-09-25

Mackey, James P. (Department: 1722)

Plastic and nonmetallic article shaping or treating: processes

Mechanical shaping or molding to form or reform shaped article

Shaping against forming surface

C425S589000, C425S595000, C425S451900

Reexamination Certificate

active

06294123

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metal mold for producing a synthetic resin molded product, particularly a thermoplastic resin molded product.
2. Description of the Prior Art
Conventionally, a producing method for a synthetic resin molded product has been well-known, in which a pair of male and female molds that are freely opened and closed are used, and the synthetic resin molded product is produced by clamping and compressing melted synthetic resin that has been supplied between the two molds.
However, in such a conventional method, the sliding faces or the contact faces of the paired male and female molds are placed along the outer circumferential line of the plane projection figure in the mold-clamping direction of a synthetic resin molded product to be obtained; consequently, burrs are produced along the outer circumferential portion of the molded product due to the melted synthetic resin entering between the sliding faces or the contact faces.
For this reason, problems are encountered in which: curved portions are not formed along the outer circumferential portion of the molded product, burrs tend to cause a cut in the hand of the worker and the product might be stuck during a line transportation, causing a jam; thus, in order to avoid these problems, an extremely time-consuming task, i.e. burr removing, is required.
Moreover, in order to form a hole in the molded product, a construction, in which a pin is put on the female mold or the male mold and the pin is allowed to contact the other mold, is generally used. However, in the conventional mold structure, the pin is only put in the same direction as the mold-clamping direction, which limits the positions of holes and the directions of holes.
In order to solve this problem, an upper-lower separation type metal mold for producing a synthetic resin molded product has been proposed, in which a first mold, a sliding mold that is allowed to slide relative to the mold, a second mold that is engaged with the siding mold and an extending device installed in the sliding mold, are provided (see Japanese Examined Patent Publication No. 16893/1991 (Tokukou-hei 3-16893).
However, in the mold of this type, the sliding mold and the second mold are fixed by the extending device, but the extending device tends to fail to sufficiently secure the sliding mold and the second mold depending on the molding conditions and types of the synthetic resin to be used.
BRIEF SUMMARY OF THE INVENTION
Under such circumstances, the inventors of the present invention have made efforts to improve the above-mentioned mold and to develop a mold for producing a synthetic resin molded product which can sufficiently secure the sliding mold and the second mold, while eliminating the generation of burrs, etc. along the outer circumferential line of the plane projection figure in the opening and closing direction of the mold, i.e. in the mold-clamping direction of the synthetic resin molded product to be obtained.
In the mold for producing a synthetic resin molded product, the present invention is to provide
(1) a metal mold for producing a synthetic resin molded product, which is characterized by comprising: a first mold, a sliding mold that is allowed to slide over the entire outer circumferential face or on a portion of said first mold, a second mold having a parting face that is capable of contacting the face of the outer circumference of said sliding mold, and a mechanical clamping mechanism that makes the outer circumferential portion of the said sliding mold mechanically coupled to said second mold,
wherein said sliding mold has a sliding direction that is the same as the opening and closing direction of the two molds, that is, the first mold and the second mold, and the sliding face between the first mold and the sliding mold is located inside the outer circumferential line, of a plane projection figure in the opening and closing direction of the metal mold, of a synthetic resin molded product which is molded by the metal mold for producing a synthetic resin molded product,
(2) the metal mold according to item no.
1
, wherein: the mechanical clamping mechanism is a mechanical clamp which is constituted by a wedge pillar having a wedge hole and a wedge that is allowed to be precisely inserted into the wedge hole, and said wedge pillar is formed on the second mold and said wedge is formed in the sliding mold, or said wedge pillar is formed on the sliding mold and said wedge is formed in the second mold,
(3) the metal mold according to item no.
1
, wherein: the mechanical clamping mechanism is a U-letter shaped clamp and the second mold and the sliding mold are provided with grooves or inserting holes at predetermined positions so that both of the ends of the clamp are inserted therein,
(4) the metal mold according to item no.
1
,
2
or
3
, wherein a melted synthetic resin path, which has an opening on the mold surface so as to supply melted synthetic resin between the molds, is formed inside the first mold or the second mold,
(5) the metal mold according to item no.
1
,
2
,
3
or
4
, wherein the synthetic resin is thermoplastic resin,
(6) a molding device which is characterized by comprising the metal mold as defined in item no.
1
,
2
,
3
,
4
or
5
,
(7) a method for producing a synthetic resin molded product, which comprises the step of mold-clamping the metal mold as defined in item no.
1
,
2
,
3
,
4
or
5
,
(8) use of the metal mold as defined in item no.
1
,
2
,
3
,
4
or
5
for producing a synthetic resin molded product.


REFERENCES:
patent: 3353221 (1967-11-01), Barnett et al.
patent: 5558883 (1996-09-01), Shinada et al.
patent: 61-63422-A (1986-04-01), None
patent: 3-16893 (1991-03-01), None

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