Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With means to close mold
Reexamination Certificate
2001-07-24
2003-07-29
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
C425S595000
Reexamination Certificate
active
06599117
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toggle lever clamping apparatus for an injection molding machine and, more particularly, to a toggle lever clamping apparatus for an injection molding machine, having a movable platen support member disposed movably on a base frame for supporting the movable platen movably along tie bars, and capable or linearly moving the movable platen relative to a stationary platen to open and close a mold an of producing a clamping force to clamp the mold.
2. Description of the Related Art
A conventional toggle lever clamping apparatus for an injection molding machine is provided with a movable platen support member which is capable of moving on a base frame. This movable platen support member is attached to a lower part of a movable platen to support it so that the toggle type clamping system achieves stable mold opening and closing operations maintaining the parallelism of the movable and the stationary mold. The movable platen support member has a frame, and rollers or wedge-shaped sliders (linear guides in some cases) supported on front and back parts of the frame on the front and the back side of the movable platen, respectively. The movable platen support platen member prevents the tilting of the movable platen during the movement of the movable platen for mold opening and closing operations, suppresses the bending of the tie bars when the movable part of the mold is attached to the movable platen and maintains the parallelism of the movable and the stationary part of the mold when the mold is opened and closed.
Referring to
FIG. 4
, a conventional toggle lever clamping system for an injection molding machine includes a stationary platen
32
fixedly set on a base frame
31
to support a stationary part
43
of a mold, a link housing
33
placed near the left end, as viewed in
FIG. 4
, of the base frame
31
so as to be movable toward and away from the stationary platen
32
, tie bars
32
extended through the four corners of the stationary platen
32
and the link housing
33
, a movable platen
36
disposed opposite to the stationary platen
32
, engaging the tie bars
34
and capable of holding the movable part
42
of the mold, a toggle link mechanism
37
having opposite ends respectively attached to the link housing
33
and the movable platen
36
, a movable platen support member
44
provided with a front roller
45
and a back roller
45
capable of rolling on the base frame
31
.
When closing and clamping the mold, the conventional toggle lever clamping system exerts forces F
1
and F
2
on the movable platen
36
. The forces F
1
and F
2
strain the movable platen
36
such that the back surface of the movable platen
36
is stretched and the movable platen
36
warps in the direction of the forces F
1
and F
2
accordingly. As the movable platen support member
44
prevents the movable platen
36
from warping and force F
2
presses the back roller
46
of the movable platen support member
44
strongly against the base frame
31
, which affects the life of the movable platen support mechanism
44
significantly and, in some cases, causes the movable platen support member
44
to be broken.
A force F
4
caused by a reaction force F
3
that acts on the lower back part of the movable platen
36
prevented from being warped by the force F
2
acts on an upper part of the movable platen
36
. Thus, the upper and the lower part of the movable platen
36
are warped differently. The unbalance in warping between the upper and the lower part of the movable platen
36
causes uneven application of mold clamping force to the mold causes irregular thickness distribution in the walls of a molding or difference in the amount of a molding material injected into the cavities of the mold between the cavities when the mold is a multicavity mold.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a toggle lever clamping apparatus for an injection molding machine, capable or solving the aforesaid problems in the conventional toggle lever clamping apparatus, of carrying out stable mold opening and closing operations, and of applying a mold clamping force uniformly to the mold to enable molding highly accurate moldings which are not different from each other in size and weight.
According to a first aspect of the present invention, a toggle lever clamping apparatus for an injection molding machine, comprises: a movable platen support member disposed movably on a base frame for supporting a movable platen supported on and guided for movement by tie bars; a toggle link mechanism for linearly moving the movable platen relative to a stationary platen to open and close a mold and for applying mold clamping force to the movable platen to clamp the closed mold; and a cushioning means for absorbing a component of the clamping force that acts on the movable platen support member when the mold is clamped so that the movable platen is allowed to be deformed for balance.
The toggle lever clamping apparatus is capable of achieving stable mold opening and closing operations, and the cushioning mechanisms included in the movable platen support mechanism permits the deformation of the movable platen when the mold is clamped. Consequently, the mold clamping force can be uniformly applied to the mold and accurate moldings which are not different from each other in size and weight can be obtained.
According to a second aspect of the present invention, the cushioning means includes a elastic member for supporting the lower back end of the movable platen on the base frame.
This toggle lever clamping apparatus is capable of achieving stable mold opening and closing operations, and the elastic mechanism included in the movable platen support mechanism permits the deformation of the movable platen when the mold is clamped. Consequently, the mold clamping force can be uniformly applied to the mold and accurate moldings which are not difficult from each other in size and weight can be obtained.
The elastic means may include coil springs or coned disk springs.
REFERENCES:
patent: 4984980 (1991-01-01), Ueno
patent: 5297952 (1994-03-01), Leonhartsberger
patent: 5454709 (1995-10-01), Leonhartsberger et al.
patent: 5511963 (1996-04-01), Hehl
patent: 23 13 183 (1974-10-01), None
Asanuma Nobuyuki
Kasal Toshihiro
Okubo Akihide
Mackey James P.
Pillsbury & Winthrop LLP
Toshiba Kikai Kabushiki Kaisha
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