Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With means to close mold
Reexamination Certificate
2000-12-06
2003-02-18
Mackey, James P. (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With means to close mold
C425S451600, C425S451700
Reexamination Certificate
active
06520766
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a mold locking device for a molding machine, and particularly to one which takes up relatively small space, and is made with relatively low cost.
A molding machine injects plastic material into a mold with a large pressure. The locking force for the mold must be greater than the injecting pressure of the molding machine, otherwise the plastic material would be pushed out of the mold, making the products have undesirable hairy edges.
Referring to
FIG. 6
, a conventional molding machine has an oil hydraulic cylinder
20
, a toggle assembly
10
, a movable mold base
30
and a stationary mold base. The movable mold base
30
and the stationary mold base each holds a respective mold half. The oil hydraulic cylinder
20
extends from the main body of the molding machine for a relatively long distance. The oil cylinder
20
and the toggle assembly
10
move the movable mold base
30
in order to open or close the mold.
However, the molding machine takes up too much space whether in transportation or in use in a factory because the oil cylinder is very long.
To overcome the disadvantage, another conventional molding machine is provided, referring to
FIGS. 7
,
8
and
9
, entitled closing unit for a die in double-toggle machines for the molding of plastic materials or for die casting, with filing number 92830069.8 and Italian patent no. 0511170A2.
The molding machine has a bearing disc
1
, a toggle assembly
2
, a movable mold base
5
, a co-moving disc
3
and two oil hydraulic cylinders
4
.
The co-moving disc
3
is movably disposed between the bearing disc
1
and the movable mold base
5
. The oil hydraulic cylinders
4
are disposed on the co-moving disc
3
(FIG.
9
). The co-moving disc
3
further has a central hole for the toggle assembly to pass through.
The toggle assembly
2
includes two first toggle arms
21
, two second toggle arms
22
, two third toggle arms
23
and two connecting arms
24
. The first toggle arms
21
are pivoted on the bearing disc
1
from outer ends, and pivoted to outer ends of the second toggle arms
22
from inner ends. The second toggle arms
22
are pivoted to outer ends of the connecting arms
24
from inner ends. The connecting arms
24
are connected to the movable mold base
5
from inner ends. The third toggle arms
23
are pivoted to the second toggle arms
22
and the co-moving disc
3
from two ends.
When a cylinder moving rod
41
of the oil cylinder
4
moves forwards, same will force the movable mold base
5
to move forwards. Thus, the movable mold base
5
pulls the connecting arms
24
and the second toggle arms
22
in the same direction; the second toggle arms
22
pivot the third arms
23
inwardly of the toggle assembly
2
to push the co-moving disc
3
and the cylinders
4
forwards. When the toggle assembly
2
is moved to a substantially straight position, the mold is closed (FIG.
7
).
The second conventional molding machine takes up less space than the first one because the oil cylinders are received between the bearing disc
1
and the movable mold base
5
. However, the mold machine has relatively high cost because it needs two oil cylinders on two side of the co-moving disc for the toggle assembly and the movable mold base to move smoothly.
SUMMARY OF THE INVENTION
Therefore, it is a main object of the present invention to provide a molding machine which can overcome the disadvantages of the above-mentioned molding machine.
The mold locking device for a molding machine of the present invention includes a toggle assembly, and a transmission.
The toggle assembly includes two first toggle arms, two second toggle arms, two third toggle arms and two connecting arms. The first toggle arms are pivoted to a bearing disc of the molding machine. The second toggle arms are each pivoted to a respective one of the first toggle arms from one end. The third toggle arms are each pivoted to an intermediate portion of the respective second toggle arm from one end, and pivoted to a co-moving disc of the molding machine from other end. The co-moving disc has a nut turnably fitted to a central portion.
The connecting arms are each pivoted to the respective second toggle arm, and a movable mold base of the molding machine from two ends. The movable mold base is provided for one of two halves of a mold to be held on.
The transmission member includes a power, an elongated screw and a connecting member. The connecting member connects the power and the nut of the co-moving disc. The elongated screw is turnably passed through the nut, and connected to the movable mold base. When the transmission member is started for the nut to turn in a first position, the nut moves forwards along the screw, pushing the co-moving disc, and the movable mold base forwards, moving the toggle assembly to a mold closing position to close the mold.
Only one transmission member is needed in place of two oil cylinder so the molding machine has relatively low cost.
REFERENCES:
patent: 4088432 (1978-05-01), Farrell
patent: 5252286 (1993-10-01), Bugatti
patent: 5603969 (1997-02-01), Guindani et al.
HWA Chin Machinery Factory Co., Ltd.
Mackey James P.
Rosenberg , Klein & Lee
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