Injection molding die

Details Injection molding die Injection molding die

2002-09-27

2004-09-21

Heitbrink, Tim (Department: 1722)

Plastic article or earthenware shaping or treating: apparatus

Female mold and charger to supply fluent stock under...

With means between charger and mold to cut off flow of...

C425S566000, C425S572000

Reexamination Certificate

active

06793481

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an injection molding die in which molding material is fed to a molding cavity via a gate. More specifically, the injection molding die is equipped with a valve gate which includes a valve pin or the like for opening and closing the gate.
BACKGROUND OF THE INVENTION
An example of an injection molding die is shown in FIG.
3
. This injection molding die
31
includes: a first die
34
having a gate
37
; a second die
50
forming, together with the first die
34
, a molding cavity
55
that communicates with the gate
37
; a manifold
40
having a molding material supply path
42
that communicates with the gate
37
; and a valve gate
56
disposed at the connection between the supply path
42
of the manifold
40
and the gate
37
of the first die
34
.
The valve gate
56
includes: a roughly cylindrical main valve unit
57
; a valve pin
58
inserted through the main valve unit
57
and opening and closing the gate
37
of the first die
34
; and a heater
59
mounted on the outer perimeter of the main valve unit
57
and heating the main valve unit
57
. The end of the main valve unit
57
abuts the perimeter edge of the gate
37
of the first die
34
, and the rear end of the main valve unit
57
abuts the perimeter edge of the opening of the supply path
42
of the manifold
40
, thus connecting the supply path
42
and the gate
37
. In this configuration, the valve gate
56
is formed as a single, integral unit from the main valve unit
57
, the valve pin
58
, and the heater
59
.
In injection molding die
31
, the main valve unit
57
, the valve pin
58
, and the heater
59
are a single, integral unit valve gate
56
. Thus, the individual elements of the valve gate
56
must be fitted to work with each other. As a result the structure of the valve gate
56
and the attachment structures for the valve gate
56
become complex. This results in more processing and assembly operations with respect to the valve gate
56
, increasing its overall price. Furthermore, a complex structure is required for sealing the valve gate
56
itself to the section where the valve gate
56
attaches to the die. This also increases processing and assembly costs, which leads to higher prices overall.
SUMMARY OF THE INVENTION
An object of the present invention is to overcome the conventional problems described above. Accordingly, the present invention provides an injection molding die that simplifies the structure of the valve gate; the structures that attach the gate and the die; processing and assembly of the gate and the die; and the sealing section structure, all of which should keep the overall price of the die and gate lower.
Accordingly, the invention provides an injection molding die which comprises: a first die with a gate; a second die forming, together with the first die, a molding cavity that communicates with the gate; a manifold comprising a molding material supply path communicating with the gate; a thermal insulation space disposed between the first die and the manifold; and a valve gate disposed between the first die and the manifold, which opens and closes the gate. The valve gate comprises: a valve pin that passes through the first die and the manifold and which opens and closes the gate; a sealing member mounted on the manifold where the valve pin passes through, which provides a seal between the manifold and the first die; and a heater mounted on the manifold to heat molding material that flows through the supply path.
The valve pin opens the gate so that the molding material flows through the supply path of the manifold and is supplied to the molding cavity. The opening of the manifold should be sealed with the sealing member, which also may seal the connection between the manifold and the first die. The molding material flowing through the supply path of the manifold may be heated by the heater.
In a further embodiment, the sealing member comprises a pressure-receiving section at an area facing the supply path of the manifold; and a seal is made between the manifold and the first die as a result of pressure from the molding material flowing through supply path that is received by the pressure-receiving section. The pressure from the molding material flowing through the supply path in the manifold acts on the pressure-receiving section of the sealing member. This results in pressure to the sealing member, providing a seal between the manifold and the first die.


REFERENCES:
patent: 4268240 (1981-05-01), Rees et al.

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