Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With preform severing means movable relative to mold
Reexamination Certificate
2001-03-15
2004-09-28
Walker, W. L. (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With preform severing means movable relative to mold
C425S139000, C425S556000
Reexamination Certificate
active
06796787
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a product ejecting apparatus and method for an injection molding machine.
2. Description of the Related Art
Conventionally, for example, a disc-molding machine is adapted to mold a disc by the steps of heating and melting within a heating cylinder a resin serving as a molding material; charging the molten resin into a cavity of a disc-making mold assembly serving as a mold apparatus; and allowing to set through cooling.
FIG. 1
is a sectional view showing a main portion of a conventional injection molding machine.
FIG. 2
is a diagram showing operation of a conventional cut punch/ejector unit. In
FIG. 2
, the x-axis represents time, and the y-axis represents projection amount.
In
FIG. 1
, reference numeral
11
denotes a movable platen. An unillustrated movable mold unit is attached to a front end face (right-hand end face in
FIG. 1
) S
1
of the movable platen
11
. A cut punch/ejector unit
12
is attached to a rear end face (left-hand end face in
FIG. 1
) S
2
of the movable platen
11
. The movable mold unit includes a base plate and a mirror-finished block attached to the base plate.
An unillustrated stationary platen is disposed in front (right-hand side in
FIG. 1
) of the movable platen
11
. An unillustrated stationary mold unit is attached to the stationary platen in such a manner as to face the movable mold unit. The stationary mold unit includes a base plate, a mirror-finished block attached to the base plate, and a stamper attached to the mirror-finished block.
An unillustrated mold-clamping unit is disposed in the rear (left-hand side in
FIG. 1
) of the movable platen
11
. The mold-clamping unit is adapted to advance/retreat (move rightward/leftward in
FIG. 1
) the movable platen
11
, thereby closing, clamping, or opening the disc-making mold assembly.
A disc is formed in the following manner. First, the mold-clamping unit is operated so as to advance (move rightward in
FIG. 1
) the movable platen
11
, thereby closing the mold. Subsequently, the mold-clamping unit is operated further to generate a mold-clamping force for clamping the mold. At this time, the mirror-finished block of the movable mold unit and that of the stationary mold unit define a cavity therebetween. Then, molten resin is injected through the injection nozzle of an unillustrated injection unit so as to fill the cavity, followed by cooling to form a disc blank. After the resin is completely cooled and before the resin sets, the cut punch/ejector unit
12
is operated so as to punch a hole in the disc blank, thereby forming a disc. Subsequently, the mold-clamping unit is operated so as to retreat (move leftward in
FIG. 1
) the movable platen
11
, thereby opening the mold. Also, the cut punch/ejector unit
12
is operated so as to advance an unillustrated ejector pin, thereby knocking out the disc from the mirror-finished block of the movable mold unit; i.e., releasing the disc from the mold.
Next, the cut punch/ejector unit
12
will be described.
A housing accommodation hole
14
is formed in the movable platen
11
in such a manner as to open at the rear end face S
2
. An annular bearing housing
15
is attached to the rear end face S
2
so as to cover the housing accommodation hole
14
. A closed-bottomed cylindrical housing
16
is attached to the front end (right-hand end in
FIG. 1
) of the bearing housing
15
while being accommodated within the housing accommodation hole
14
. Two bearings
17
and
18
are disposed within the bearing housing
15
. A first ball nut
19
is rotatably supported by the bearings
17
and
18
. The first ball nut
19
has a flange portion
21
at the rear end (left-hand end in
FIG. 1
) thereof. An annular driven pulley
22
is fixedly attached to the flange portion
21
. A second ball nut
23
is attached to the pulley
22
. The second ball nut
23
has a flange portion
24
at the front end thereof. The flange portion
24
is fixedly fitted into the pulley
22
.
A servomotor
26
serving as drive means is disposed. A timing belt
29
is looped around and extends between the driven pulley
22
and a drive pulley
28
attached to an output shaft
27
of the servomotor
26
. The pulleys
22
and
28
and the timing belt
29
constitute rotation transmission means. Reference numeral
31
denotes an encoder serving as a rotational-speed detector for detecting the rotational speed of the servomotor
26
.
The first ball nut
19
has a stepped portion
33
adjacent to the rear end of the bearing
17
, while a cylindrical positioning ring
34
is disposed on the outer circumferential surface of the first ball nut
19
adjacent to the front end of the bearing
18
. The front end of the first ball nut
19
and a positioning nut
35
are screw-engaged. The positioning nut
35
is tightened so as to hold the bearings
17
and
18
by means of the stepped portion
33
and the positioning ring
34
, thereby positioning the first ball nut
19
with respect to the bearing housing
15
.
A hole
43
is formed in the movable platen
11
in such a manner as to extend therethrough. A cylindrical cut punch unit
37
is disposed within the hole
43
, the first ball nut
19
, and the bearing housing
15
such that it can reciprocate. The cut punch unit
37
includes, from the rear end to the front end, a ball screw portion
38
having, for example, right-hand threads formed on the outer circumferential surface thereof, a spline portion
39
having a spline formed on the outer circumferential surface thereof, and a cut punch rod
44
. Right-hand threads are formed on the inner wall surface of the first ball nut
19
so as to establish screw engagement between the first ball nut
19
and the ball screw portion
38
. A spline is formed on the housing
16
so as to establish spline engagement between the housing
16
and the spline portion
39
. A cylindrical cut punch serving as a working member is disposed within the movable mold unit. The rear end of the cut punch is connected to the front end of the cut punch rod
44
. The first ball nut
19
and the ball screw portion
38
constitute motion conversion means for converting rotary motion of the first ball nut
19
to linear motion of the ball screw portion
38
. The spline portion
39
constitutes rotation restriction means for restricting rotation of the cut punch unit
37
.
Two guide bars
45
and
46
are attached to the rear end face of the bearing housing
15
in such a manner as to extend rearward. A plate
47
is disposed on the guide bars
45
and
46
such that it can reciprocate along the same. A ball screw
48
is attached to the plate
47
in such a manner as to extend forward. Inverse threads with respect to the threads formed on the outer circumferential surface of the ball screw portion
38
; for example, left-hand threads, are formed on the outer circumferential surface of the ball screw
48
. For example, left-hand threads are formed on the inner wall surface of the second ball nut
23
so as to establish screw engagement between the second ball nut
23
and the ball screw
48
. An ejector rod
51
is formed at the front end of the ball screw
48
in such a manner as to extend forward through the cut punch unit
37
. An ejector pin is disposed within the cut punch. The rear end of the ejector pin is connected to the front end of the ejector rod
51
. The second ball nut
23
and the ball screw
48
constitute motion conversion means for converting rotary motion of the second ball nut
23
to linear motion of the ball screw
48
. The plate
47
constitutes rotation restriction means for restricting rotation of the ball screw
48
.
Next, operation of the thus-configured cut punch/ejector unit
12
will be described.
First, drive control means of an unillustrated controller causes the servomotor
26
to rotate in the regular direction. Rotation in the regular direction is transmitted to the first and second ball nuts
19
and
23
via the output shaft
27
, the pulley
28
, the timing belt
29
, and the pulley
22
. Acco
Luk Emmanuel S.
Squire Sanders & Dempsey L.L.P.
Sumitomo Heavy Industrie's, Ltd.
Walker W. L.
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