Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With means to cause relative movement between mold and charger
Reexamination Certificate
2000-07-28
2003-02-25
Heitbrink, Tim (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With means to cause relative movement between mold and charger
Reexamination Certificate
active
06524095
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an injection molding machine and particularly to a nozzle touch mechanism of the injection molding machine.
2. Description of Related Art
In an injection molding machine for molding a product by injecting molten material such as resin and metal into a cavity formed by a stationary mold and a movable mold from a nozzle provided at a distal end of a heating cylinder of an injection mechanism, a nozzle touch mechanism is provided for moving the injection mechanism relatively to a stationary platen to which the stationary mold is attached so that the nozzle is pressed towards and retracted from a spool of the stationary mold.
FIG. 11
shows a conventional nozzle touch mechanism of an injection molding machine. In
FIG. 11
, a stationary mold
40
is attached to a stationary platen
30
and a bearing unit
31
for supporting one end of a ball-screw shaft
61
rotatably but axially unmovably is fixed to the stationary platen
30
. The other end of the ball-screw shaft
61
is connected to an output shaft of a motor
65
through a coupling
64
. A ball-screw nut
62
is threadedly engaged with the ball-screw shaft
61
and supported unrotatably with respect to an extruder bed
20
. A spring
63
is intervened between the ball-screw nut
62
and the extruder bed
20
. An injection mechanism
10
is mounted on the extruder bed
20
and connected thereto via a swivel pin
21
for a swivel motion. The extruder bed
20
is guided by a linear guide having a guide rod or rail, not shown, movably close to and away from the stationary platen
30
. Thus, the injection mechanism
10
is allowed to linearly move towards and away from the stationary platen
30
with the extruder bed
20
and also to swivel about the swivel pin
21
on the extruder bed
20
.
For performing a nozzle touch, the motor
65
is driven to rotate the ball-screw shaft
61
such that the ball-screw nut
62
which is unrotatably supported moves forward to the stationary platen
30
(right-hand direction in FIG.
11
). The ball-screw nut
62
moves the extruder bed
20
forward through the spring
63
so that a nozzle
10
a
at a distal end of a heating cylinder
10
b
of the injection mechanism
10
touches a spool of the stationary mold
40
attached to the stationary platen
30
. The servomotor
65
is continuously driven after the nozzle
10
a
touches the spool of the mold
40
to forward the ball-screw nut
62
to make the spring
63
compressed to urge the extruder bed
20
and the injection mechanism
10
toward the stationary platen
30
so that the nozzle
10
a
presses the mold
40
by an elastic force of the spring
63
. This pressing force applied from the nozzle
10
a
to the spool of the stationary mold
40
, i.e. a nozzle tough force is transmitted from the stationary mold
40
to the stationary platen
30
to produce a moment to incline the stationary platen
30
and the stationary mold
40
as shown by the dotted line in FIG.
11
.
The inclination of the stationary mold
40
causes opposing faces of a movable mold (not shown) and the stationary mold
40
to be nonparallel to each other, which may raise a problem of damaging pins guide holes provided at the opposing faces by an interference between them in clamping the molds by a clamping mechanism.
In order to solve the above problem, there is known from Japanese Patent Publication No. 9-277306 a nozzle tough mechanism for preventing a bending moment on the stationary mold by the nozzle tough force by fixing one end of a rotation/linear-motion converting mechanism such as the ball screw mechanism on the stationary platen laterally with respect to a position of the nozzle tough.
FIGS. 12
a
and
12
b
are a plan view and a side view, respectively, of the nozzle touch mechanism known from Japanese Patent Publication No. 9-277306 for preventing the bending moment on the stationary platen.
In
FIGS. 12
a
and
12
b,
the same or equivalent member as shown in
FIG. 11
is indicated by the same reference numeral and a reference numeral
32
denotes a fixing member for fixing one end of the ball-screw shaft
61
on the stationary platen
30
. As seen from
FIGS. 12
a
and
12
b,
fixing points of the ball-screw shafts
61
are arranged at opposite positions with respect to the nozzle touch position. Specifically, levels of the fixing points of the ball-screw shafts
61
are substantially the same as the level of the nozzle touch position.
Forward and backward motions of the injection mechanism close to and away from the stationary platen
40
are performed by a rotation of the motor
65
. The rotation of the motor
65
is transmitted to the ball-screw nuts
62
through a gear transmission mechanism
66
to rotate the ball-screw nuts
62
in synchronism with each other. Since the ball-screw nuts
62
are supported by the injection mechanism
10
to be rotatable but unmovable in the axial direction of the ball-screw shafts
61
relative to the injection mechanism
10
, and the ball-screw shafts
61
are fixed to the stationary platen
30
, the ball-screw nuts
62
are moved in the axial direction by a lead of the ball-screw shaft with one rotation thereof. With the axial motion of the ball-screw nuts
62
, the injection mechanism
10
connected fixedly with respect to the axial direction is moved forward and backward with respect to the stationary platen
30
. When the nozzle
10
a
at the distal end of the heating cylinder
10
b
touches the spool of the stationary mold
40
attached to the stationary platen
30
and applies pressure to the spool, no bending moment is produced on the stationary platen
30
since the stationary platen
30
is connected to the ball-screw shafts
61
at the same-level as that of application of the nozzle touch force, so that the stationary platen
30
and the stationary mold
40
are prevented from being inclined.
In the nozzle touch mechanism for preventing the stationary mold and the stationary platen from being inclined by the nozzle touch force as shown in
FIGS. 12
a
and
12
b,
the ends of the ball-screw shafts have to be arranged on opposite positions on the stationary platen at the same level as that of the nozzle touch position on the stationary mold. This means that the ball-screw shafts are arranged parallel with each other at the same level as that of the heating cylinder of the injection mechanism. Further, the ball-screw nuts have to be driven in synchronism with each other to exert driving force to the injection mechanism
10
at the same speed. To meet these requirements, there arises a problem that the driving mechanism of the nozzle touch mechanism is complicated.
Further, the ball screw mechanisms arranged on both sides of the heating cylinder are inconvenient in maintenance and inspection of the heating cylinder. In order to carry out the maintenance and inspection of the heating cylinder including an exchange of the heating cylinder or the injection screw for a new one, it is necessary to retract the injection mechanism to the position where the nozzle does not interfere with the stationary platen
30
and swivel the injection mechanism on the extruder bed
20
about the swivel pin
21
. The above arrangement requires removal of the connection between the stationary platen
30
and the ball-screw shafts
61
of the ball-screw mechanism as a rotation/linear-motion converting mechanism. Furthermore, after finishing the maintenance or inspection, it is necessary to adjust the center of the ball-screw shaft of the ball screw mechanism to retrieve the operational state, so that operations for the maintenance and inspection of the heating cylinder are made laborious.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an injection molding machine capable of preventing inclination of a mold and a stationary platen by a nozzle touch force and carrying out maintenance and inspection of the injection mechanism with ease.
An injection molding machine of the present invention comprises a nozzle touch mechanism for mo
Ban Yonbon
Ito Susumu
Fanuc Ltd.
Heitbrink Tim
Staas & Halsey , LLP
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