Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With means to lock mold in closed position
Reexamination Certificate
2002-03-01
2004-05-11
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 lock mold in closed position
Reexamination Certificate
active
06733275
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a split nut opening/closing device for tie bar, which is applied to a mold clamping apparatus for an injection molding machine, a pressing machine, or the like. More particularly, it relates to an electric split nut opening/closing device in a mold clamping apparatus, which has a simple construction and high response.
2. Description of Related Art
Conventionally, in the mold clamping apparatus for an injection molding machine, a movable platen is brought closer to a fixed platen generally fixed to an apparatus base by using a cylinder with a small diameter and a large stroke, and thereby molds attached to the movable and fixed platens are brought into contact with each other, by which mold closing is performed. At this time, a two-piece nut (split nut) is engaged with and connected to a threaded portion at the tip end of each of four tie bars that are fixed to one platen and project from the other platen, by which a mold clamping force is generated by giving tension to the tie bar using a large-diameter and small-stroke cylinder. As an opening/closing device for this split nut, various types of devices have so far been proposed.
First Conventional Example
A “mold clamping split nut opening/closing device” (Unexamined Japanese Utility Model Publication No. 4-87218) of a type such that a split nut is opened and closed horizontally using an electric motor will be described as a first conventional example with reference to
FIGS. 9 and 10
.
As shown in
FIG. 9
, this split nut
1
consists of a pair of, left and right, half pieces A and B. A slide box
4
is disposed in an upper space between the half pieces A and B, and two guide rods
5
are inserted in the side portions of the half pieces A and B and the slide box
4
. In the lower part, one guide rod
5
is inserted in the half pieces A and B. Both ends of each of these guide rods
5
are fixed to the half piece A and a plate
7
. The half piece B and the slide box
4
are slidable via bushes
15
and
16
, respectively. The slide box
4
is slidably supported by a guide stand
3
projecting from a position just over a tie bar
2
of a fixed platen (not shown), and is configured so as to be movable in the axial direction (direction perpendicular to the paper in
FIG. 9
) of the tie bar
2
.
The plate
7
is fitted with an electric motor
23
via a bracket
21
. To an output shaft
22
of the electric motor
23
, a ball screw
20
is connected via a coupling
35
. Also, the ball screw
20
is inserted in a hole
36
in the half piece B and a hole
37
in the plate
7
, and is engaged with a ball nut
19
. The ball nut
19
is fixed to the half piece B via an adapter plate
27
, thus forming opening/closing drive means for the split nut
1
.
Also, on the bottom surface of the slide box
4
is protrusively provided a support pin
10
, and on the top surfaces of the left and right half pieces A and B are protrusively provided pins,
12
a
and
12
b
, respectively. As shown in
FIG. 10
, the support pin
10
is inserted in a round hole in the center of a link plate
11
, and pins
12
a
and
12
b
are inserted in elongated holes at both ends thereof.
Reference numeral
25
denotes a slit plate fixed to the coupling
35
, and
26
denotes a pulse sensor fixed to the bracket
21
. By these elements, the rotation of the ball screw
20
is counted to find the position of the half piece B.
In order to close the split nut
1
in the open state in which the half pieces A and B are separated, the electric motor
23
is rotated in the direction such that the ball nut
19
is moved away. The half piece B is moved in the direction such as to come closer to the half piece A, and the pin
12
b
turns the link plate
11
around the support pin
10
in the closing direction (counterclockwise direction in FIG.
10
). At this time, the link plate
11
turning in the closing direction moves the half piece A in the closing direction (right direction in
FIG. 10
) via the pin
12
a
. Thus, the half pieces A and B move while always maintaining the symmetrical position with respect to the tie bar
2
lying in the same position as the support pin
10
.
Inversely, in order to open the closed split nut
1
, the above-described operation has only to be performed entirely reversely, so that the explanation thereof is omitted.
The engagement phase of the threaded portion of the split nut
1
with the tie bar
2
is adjusted by an engagement adjusting device, not shown.
Second Conventional Example
Although the above-described split nut opening/closing device is provided on each of four tie bars in the first conventional example, a split nut opening/closing device for opening and closing two split nuts by one cylinder has been proposed as a closing device in a “mold fixing device of injection and compression molding machines” (Japanese Patent Publication No. 37-8490). This device will be described as a second conventional example.
FIG. 11
shows an opening/closing device (closing device)
50
. In
FIG. 11
, reference numeral
51
denotes a movable platen (movable attachment plate),
52
denotes a tie bar (transverse rod),
53
denotes a cylinder,
54
denotes two pistons in the cylinder
53
,
55
denotes two rods (piston rods),
56
denotes a conduit tube. The rod
55
is connected to one end of a link plate (bent rod)
57
, and the other end of the link plate
57
holds one end of a half piece
58
of a split nut (holding member). The other end of the half piece
58
is rotatably supported by a pin (shank)
59
provided on the movable platen
51
.
When a pressure oil is supplied from the conduit tube
56
to two oil chambers
53
a
on both sides of the cylinder
53
, the rod
55
decreases its stroke, so that the link plate
57
turns so as to be horizontal, increasing the transverse length. The half piece
58
is turned around the pin
59
to be opened, by which the connection with the tie bar
52
is released. Also, when the pressure oil is inversely supplied to an oil chamber
53
b
on the center of the cylinder
53
, the rod
55
increases its stroke, so that the link plate
57
turns so as to form an angle with respect to the horizon, whereby the half piece
58
is turned and closed.
In this device, which of the two rods
55
and the half piece
58
moves earlier cannot be determined unequivocally.
The opening/closing device of the first conventional example is of a type such that the electric motor
23
is driven to linearly move the half pieces A and B, by which the split nut is opened and closed to the right and left. Therefore, the opening/closing device of this type has an advantage of high response, but has a disadvantage of complicated construction because the opening/closing device is provided on each of the four tie bars
2
.
The opening/closing device of the second conventional example is of a type such that one cylinder
53
is used for two upper and lower tie bars
52
to rotationally move the half pieces
58
on the circumference, by which the split nut is opened and closed to the right and left. Therefore, the opening/closing device of this type has an advantage of simple construction of device because two split nuts are opened and closed by one cylinder
53
, but has disadvantages of low response because of the use of the cylinder
53
and less unequivocalness of the motion of the rod
55
of the cylinder
53
and the half piece
58
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electric split nut opening/closing device in a mold clamping apparatus, in which an electric motor is driven to linearly move a half piece while unequivocally restraining the motion, by which two right and left tie bars are opened and closed at the same time by one device.
To solve the above problems, the present invention provides solving means by using the configurations described below.
The present invention provides an electric split nut opening/closing device in a mold clamping apparatus in which a fixed platen for holding a fixed mold and a
Mackey James P.
Mitsubishi Heavy Industries, LTD
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