JP2001047484A - Injection compression molding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a molded article free from strain, a sink or surface irregularity and having a predetermined shape/dimension when the compression molding of a molten material is performed by using an injection compression molding apparatus. SOLUTION: In an injection compression molding apparatus, the protruding lengths of tie bars 20a-20d from a fixed platen 12 at a time of the advance operation of a movable platen 14 toward the fixed platen 12 at a time of the compression molding of a molten material are detected by displacement sensors 40a-40d and a control circuit adjusts the opening degree of a solenoid valve on the basis of the detection result to adjust the oil pressures in the hydraulic cylinders 46a-46d arranged to the fixed platen 12. As a result, the moving speed of the tie bars larger than other ones in protruding length becomes slow and the moving speed of short tie bars becomes fast. By this constitution, since the parallilism of the movable platen 14 to the fixed platen 12 is kept highly accurate, a molded article free from strain, a sink or surface irregularity and having a predetermined shape/dimension can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection compression molding apparatus, and more particularly, to moving an movable platen toward a fixed platen during compression molding. The present invention relates to an injection compression molding apparatus in which parallelism is maintained with high accuracy.

[0002]

2. Description of the Related Art As an example of converting an injection molding apparatus to an injection compression molding apparatus, there is a modification of a tie bar lock type injection molding apparatus. The modified tie-bar lock type injection molding apparatus includes a fixed plate having a first mold installed on one side and a movable plate having a second mold installed on one side. Are connected by a plurality of tie bars. For example, a piston rod of a hydraulic cylinder is connected to the movable plate, and the movable plate approaches or separates from the fixed plate as the piston rod moves forward or backward.

In the case of manufacturing a resin molded product using the modified tie bar lock type injection molding apparatus, first, a piston rod is moved forward to form a cavity by the first mold and the second mold. I do. In this state, the movable platen is fixedly positioned on the tie bar by the lock mechanism.

[0004] Next, a molten resin (hereinafter, referred to as molten metal)
From the injection mechanism into the cavity. Then, before the molten metal is completely solidified, the molten metal is compressed and formed. Specifically, the tie bar on which the movable platen is fixed and positioned is directed toward the fixed platen and moved forward. As a result, the second
The mold is further approached to the first mold so that both are in close contact with each other, and the molten metal is compression molded.

Finally, by solidifying the compression-molded molten metal, a resin molded product is obtained.

[0006]

However, in the modified injection molding apparatus according to the prior art described above, it is difficult to keep the fixed platen and the movable platen parallel to each other when performing the compression molding of the molten metal. There is a problem that there is.

That is, the movement of the movable platen to the fixed platen, in other words, the approach of the second die to the first die is performed in two stages as described above. In the process in which the mold and the second mold come into close contact, part of the molten metal leaks out of the cavity. The amount of this leakage differs depending on the location of the leakage. Therefore, it is easy to make the second mold close to the first mold in a place where the leakage amount is small, but it is difficult to make the second mold close to the first mold in a place where the leakage amount is large. This is because

In other words, it is easy to move the movable platen to the fixed platen side during the compression molding of the molten metal in a place where the amount of the molten metal leaks is small, but it is difficult in a place where the amount of the molten metal leaks is large.
Therefore, the movable plate is tilted, so that the second die approaches the first die while tilting. As a result, it is difficult to bring both molds into complete close contact. When such a situation occurs, a molded product having a predetermined shape and dimensions cannot be obtained. In addition, distortion, sink marks, surface spots, and the like may occur in the molded product, resulting in variations in the quality of the molded product.

As a result, when a molded article of resin is manufactured by using a modified injection molding apparatus according to the prior art, there is a problem that the yield of the molded article is low.

To solve this problem, Japanese Patent Laid-Open Publication No.
It is considered that it is effective to install the mold clamping device disclosed in JP-A-9750 and JP-A-8-118441 in an injection molding device. However, since these mold clamping devices require many hydraulic drive mechanisms and control mechanisms for controlling them, capital investment increases when installed in an injection molding device, and as a result, manufacturing of molded products The problem of raising costs is revealed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and can maintain the parallelism between a movable plate and a fixed plate during compression molding of a molten metal with a simple configuration. It is an object of the present invention to provide an injection compression molding apparatus capable of producing a molded article having a predetermined shape and dimensions without distortion, sink marks, surface irregularities, and the like.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first mold provided on one side of a fixed plate, and a movable plate which can be moved toward or away from the fixed plate. A second mold installed on a side surface, a plurality of tie bars connecting the fixed plate and the movable plate, and the movable plate until a cavity is formed by the first mold and the second mold. A first drive mechanism for moving toward the fixed platen;
An injection mechanism installed on the other side of either the fixed platen or the movable platen for injecting molten metal into the cavity, and directing the movable platen toward the fixed platen after the molten metal is injected into the cavity. A second drive mechanism for moving further, and a plurality of support mechanisms mounted on the same side as one of the first mold and the second mold and supporting one of the fixed platen and the movable platen. A plurality of displacement sensors for detecting the degree of parallelism between the fixed platen and the movable platen when the second drive mechanism is biased, and based on detection results of the plurality of displacement sensors. Control means for controlling the pressure of each pressure fluid in the plurality of cylinders.

When the displacement sensor detects that the movable plate is tilted, the control means adjusts the pressure of the pressure fluid in the plurality of cylinders. That is,
Cylinders at locations where the moving speed of the movable platen moves fast are difficult to push the piston rod, while cylinders at locations where the moving speed is slow are easy to push the piston rod. As a result, the inclination of the movable platen is constantly corrected, so that the parallelism between the fixed platen and the movable platen is maintained. Therefore, it is possible to manufacture a molded article having a predetermined shape and dimensions without distortion, sink mark, and surface unevenness. Moreover, the configuration is simple.

Preferably, the injection compression molding apparatus further includes a rod receiver for receiving each of the piston rods of the plurality of cylinders, and a limit switch is provided on the rod receiver. The injection of the molten metal from the injection mechanism is automatically performed by a delay timer or the like.

A preferred example of the injection compression molding apparatus is a tie bar lock type injection compression molding apparatus having a lock mechanism for fixing and positioning the movable platen to the tie bar when a cavity is formed. In this case, the movable plate moves toward the fixed plate by the second drive mechanism moving the tie bar toward the fixed plate and moving forward. Therefore, if the length of protrusion of the tie bar from the fixed plate is detected by the displacement sensor, the above control can be easily performed.

Another preferred example of the injection compression molding apparatus is one in which the first drive mechanism also functions as the second drive mechanism. In this case, if the displacement of the drive unit of the first drive mechanism is detected by the displacement sensor and the forward speed of the drive unit is adjusted, the above control can be easily performed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an injection compression molding apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an overall schematic configuration diagram of an injection compression molding apparatus 10 according to the present embodiment. In the injection compression molding apparatus 10, a fixed board 12 is provided on the left side, and a movable board 14 is provided on the right side. Movable plate 14
Are the piston rods 18 of the hydraulic cylinders 16a and 16b.
The a and 18b can move toward and away from the fixed platen 12 by moving forward and backward. The fixed platen 12 and the movable platen 14 have four tie bars 2 at each corner.
0a to 20d.

A first mold 2 is provided on one side of the fixed platen 12.
2 is provided, while a second mold 24 is provided on one side surface of the movable platen 14, and the two molds 22, 24 face each other. Among these, the first die 22 has the fixed platen 1
A passage 28 is provided for introducing the molten metal injected from the injection mechanism 26 installed on the other side of the second mold into the cavity formed by the first mold 22 and the second mold 24. A tie bar 20 is provided on the other side of the movable platen 14.
The movable platen 1 is provided at each of the corners through which a to 20d are inserted.
In order to fix and position the 4 on the tie bars 20a to 20d, movable plate fixtures 30a to 30d including a pair of hydraulic cylinders facing each other are provided. That is, the tie bars 20a to 20d are formed with teeth 32a to 32d, respectively.
0d is formed with teeth 34a to 34d that mesh with the teeth 32a to 32d. Therefore, for example, the movable platen 14 is fixed to the tie bar 20a by extending the piston rod of the movable platen fixture 30a to mesh the teeth 32a and the teeth 34a with each other. Similarly, if the teeth 32b to 32d of the tie bars 20b to 20d and the teeth 34b to 34d of the movable plate fixtures 30b to 30d mesh with each other, the movable plate 14 is fixedly positioned on the tie bars 20a to 20d. That is, the injection compression molding apparatus 10
Is a tie-bar lock type.

Further, double-acting hydraulic cylinders 36a to 36d are provided on the other side surface of the fixed platen 12, and each of the tie bars 20a to 20d is used for compression molding of the molten metal.
These double-acting hydraulic cylinders 36a to 36d move forward toward the fixed platen 12 side.

The tie bars 20a to 20a
Ends 38a-3 protruding toward the fixed plate 12 side in 20d
8d sequentially protrude, and the end portions 38a-3
The protruding length of each of the displacement sensors 40a to 40d
It is always detected by d. That is, the ends 38a to 38
d and tip portions 42a to 42d of displacement sensors 40a to 40d
Are connected by bars 44a to 44d, respectively, so that the tips 42a to 42d are connected to the ends 38a
３８38d is protruded as it protrudes. The displacement sensors 40a to 40d determine the leading lengths of the tip portions 42a to 42d at this time by the end portions 38a to 38d of the tie bars 20a to 20d.
Is detected as the length of the protrusion.

As shown in FIG. 1 and FIG. 2 which is a sectional view taken along line II-II in FIG. 1, four hydraulic cylinders 46a to 46d are provided outside the corners of the first mold 22. Is installed. On the other hand, outside the corners of the second mold 24, rod receivers 50a with which the piston rods 48a to 48d of the hydraulic cylinders 46a to 46d abut respectively.
~ 50d are installed. These rod receivers 50a-
A limit switch (not shown) is arranged on an end face of the injection mechanism 50d. When the limit switches are urged when the piston rods 48a to 48d come into contact with the end face, the injection of the molten metal from the injection mechanism 26 starts. Is done.

Here, as shown in FIG.
Reference numerals 0a to 40d are electrically connected to the control circuit 52, and the detection results are always sent to the control circuit 52 as electric signals. On the other hand, electromagnetic valves 54a to 54d are interposed in an oil discharge system (not shown) from the hydraulic cylinders 46a to 46d to an oil supply source (not shown), and these electromagnetic valves 54a to 54d are also electrically connected to the control circuit 52. Connected.

That is, the control circuit 52 includes the displacement sensor 4
Tie bar 20a-20d detected by 0a-40d
Solenoid valve 54a according to the protruding length of the ends 38a to 38d of the solenoid valve 54a.
Adjust the opening of ~ 54d. Thereby, the hydraulic cylinder 4
The hydraulic pressure in 6a to 46d is adjusted, and as a result, the parallelism between the fixed platen 12 and the movable platen 14 is maintained as described later. As will be understood from this, the hydraulic cylinders 46a to 46d support the movable platen 14 during the compression molding of the molten metal.

Next, the operation of the injection compression molding apparatus 10 configured as described above will be described by taking as an example the case of manufacturing a resin molded product.

First, by urging the piston rods 18a, 18b of the hydraulic cylinders 16a, 16b forward,
The movable platen 14 located at the location shown in FIG. 1 is moved toward the fixed platen 12 side, and as shown in FIG.
Then, the cavity 56 is formed by the second mold 24.
Then, the piston rods 58a to 58d of the movable platen fixtures 30a to 30d are extended, and the movable platen fixtures 30a to 30d are extended.
d are formed on the tie bars 20a-34d.
The teeth are meshed with the teeth 32a to 32d formed at 20d.
Due to this engagement, the movable platen 14 becomes tie-bars 20a to 20d.
Is fixedly positioned. In addition, the piston rods 48a-
In the case where the distance between 48d and rod receivers 50a to 50d is shorter than the distance between cavities 56, shims 60 may be provided on the respective end faces of rod receivers 50a to 50d to adjust the distance (see FIG. 1 and FIG. 1). (See FIG. 4).

At this time, the piston rods 48a to 48d of the hydraulic cylinders 46a to 46d installed on the fixed board 12
Are rod receivers 50a to 50d installed on the movable platen 14.
Abuts the end face of Due to this contact, the limit switches provided in the rod receivers 50a to 50d are urged, and after a predetermined time has elapsed, the injection of the molten metal L from the injection mechanism 26 to the cavity 56 via the passage 28 is started. You.

When a predetermined time elapses after the injection of the molten metal L is completed, the double-acting hydraulic cylinders 36a to 36d are automatically energized. Thus, the tie bars 20a to 20d move forward toward the fixed platen 12 side. Therefore, the second
As the mold 24 comes closer to the first mold 22, the distance between the cavities 56 is reduced. As a result, the molten metal L is compressed and formed in accordance with the shape of the cavity 56 having a reduced interval.

During the compression molding of the molten metal L, for example, if much of the molten metal L leaks above the cavity 56, the control circuit 52 sets the hydraulic cylinder 46 as follows.
Adjust the hydraulic pressure of a to 46d.

In this case, the moving speed of the movable platen 14 is lower on the upper side than on the lower side due to the leaked molten metal L. Therefore, each end 38a-3 of the tie bar 20a-20d
The protruding length of the 8d from the fixed plate 12 is equal to the end portions 38b, 38
c is longer than the ends 38a and 38d.

The protruding length of these ends 38a to 38d is
The displacement sensors 40a to 40d
-40d are detected as the lengths of the leading ends 42a-42d. As described above, this detection result is always sent to the control circuit 52 as an electric signal. That is, the control circuit 52 detects an end having a longer (or shorter) protruding length than the other end, in other words, a tie bar whose moving speed is faster (or slower) than the other tie bars. . Then, based on the detection result, the control circuit 52 controls the solenoid valves 54a to 54d so that the tie bar having a high moving speed is slow and the tie bar having a low moving speed is fast.
Adjust the opening of.

In the case of the above example, the moving speed is the tie bar 2
Since 0a and 20d are slower and tie bars 20b and 20c are faster, the control circuit 52 opens the solenoid valves 54a and 54d and throttles the solenoid valves 54b and 54c. Thereby, the piston rods 48a, 4d of the hydraulic cylinders 46a, 46d are
8d can be easily pushed in and the piston rods 48 of the hydraulic cylinders 46b and 46c can be inserted.
It becomes difficult to push in b and 48c.

The control circuit 52 adjusts the opening of the solenoid valves 54a to 54d as described above, so that the
a and 20d move faster, while the tie bar 20
The moving speeds of b and 20c decrease. And tie bar 2
At the time when the protruding lengths of the end portions 38a to 38d of the fixed portions 12a to 38d from the fixed platen 12 are all equal, the control circuit 52
Adjust so that the opening degrees of 4a to 54d are equal. That is, the piston rods 4 of the hydraulic cylinders 46a to 46d
8a to 48d can be equally pushed, and the moving speeds of the tie bars 20a to 20d are all equal. By adjusting the hydraulic pressures of the hydraulic cylinders 46a to 46d in this way, the parallelism between the fixed platen 12 and the movable platen 14 is maintained.

The molten metal L thus compacted is then cooled and completely solidified. Thereafter, the movable platen 14 is moved backward from the fixed platen 12 by the double-acting hydraulic cylinders 36a to 36d, and the tooth portions 34 of the movable platen fixtures 30a to 30d are moved.
a to 34d are replaced with the teeth 32a to 3 of the tie bars 20a to 20d.
2d, and the hydraulic cylinders 16a, 16
If the movable platen 14 is separated from the fixed platen 12 by urging the piston rods 18a and 18b of b to retreat, a resin molded product can be obtained.

During the compression molding of the molten metal L, since the parallelism between the fixed platen 12 and the movable platen 14 is maintained as described above, no distortion, sink mark, surface unevenness or the like is observed in the obtained molded product. . In addition, since a cavity having a predetermined shape is formed at the time of compression molding, a molded product having a predetermined shape and dimensions can be obtained. After all, by performing the compression molding of the molten metal L using the injection compression molding apparatus 10, the yield of molded products can be improved.

In the above embodiment, the tie bar 20a is used as the injection compression molding apparatus 10 during compression molding.
Although the tie bar lock type in which the movable plate 14 to 20 d moves forward is illustrated, an injection compression molding device in which the movable platen 14 is moved forward by the hydraulic cylinders 16 a and 16 b during compression molding may be used. In this case, the displacement sensors 40a to 40d detect the piston rods 18a, 1b of the hydraulic cylinders 16a, 16b.
8b is detected, and the piston rods 18a, 18a, 1b are detected.
8b may be adjusted.

Also, in this embodiment, the hydraulic cylinders 46a to 46d are installed on the fixed
a to 50d are installed on the movable platen 14, but the hydraulic cylinders 46a to 46d are installed on the movable platen 14,
0 a to 50 d may be installed on the fixed board 12.

[0038]

As described above, according to the injection compression molding apparatus of the present invention, when the movable platen moves forward toward the fixed platen during the compression molding of the molten metal, the parallelism between them is high. Accuracy is maintained. For this reason, it is possible to obtain a molded product in which distortion, sink marks, surface spots, and the like are not recognized and have a predetermined shape and dimensions. Therefore, the yield of molded products is significantly improved.

In the injection compression molding apparatus according to the present invention, the parallelism between the movable platen and the fixed platen can be maintained with a simple configuration. Therefore, high capital investment costs are not required, and the effect that a high-quality molded product can be manufactured without increasing manufacturing costs is achieved.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an injection compression molding apparatus according to the present embodiment.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a schematic explanatory view showing a control system for adjusting a hydraulic pressure of a hydraulic cylinder included in the injection compression molding apparatus of FIG.

FIG. 4 is a partial longitudinal sectional view showing a state in which a molten metal is injected into a cavity.

FIG. 5 is a partial longitudinal sectional view showing a state where an injected molten metal is compression-molded.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Injection compression molding apparatus 12 ... Fixed board 14 ... Movable board 16a, 16b, 46a-46d ... Hydraulic cylinder 18a, 18b, 48a-48d, 58a-58d ... Piston rod 20a-20d ... Tie bar 22 ... 1st mold 24 .. Second mold 26 Injection mechanism 30a-30d Movable platen fixture 36a-36d Double acting hydraulic cylinder 40a-40d Displacement sensor 50a-50d Rod receiver 52 Control circuit 54a-54d Solenoid valve 56 Cavity L: molten metal

Claims (4)

[Claims] A first mold provided on one side surface of a fixed plate; a second mold provided on one side surface of a movable plate capable of approaching or separating from the fixed plate; A plurality of tie bars connecting the board, a first drive mechanism for moving the movable board toward the fixed board until a cavity is formed by the first mold and the second mold, An injection mechanism installed on the other side of either the fixed platen or the movable platen for injecting molten metal into the cavity; and directing the movable platen toward the fixed platen after the molten metal is injected into the cavity. A second drive mechanism for further moving the first and second molds, the plurality of second drive mechanisms being installed on the same side as one of the first mold and the second mold and supporting one of the fixed platen and the movable platen. The cylinder and the second drive mechanism A plurality of displacement sensors for detecting the parallelism between the fixed platen and the movable platen when energized; and a pressure sensor for each of the plurality of cylinders based on a detection result of the plurality of displacement sensors. An injection compression molding apparatus, comprising: control means for controlling pressure. 2. The injection compression molding apparatus according to claim 1, further comprising a rod receiver for receiving each piston rod of said plurality of cylinders, wherein said rod receiver is provided with a limit switch. Injection compression molding equipment. 3. The injection compression molding apparatus according to claim 1, further comprising: a lock mechanism for fixing and positioning said movable platen to said tie bar when a cavity is formed, wherein said second drive mechanism is provided with said second drive mechanism. By moving the tie bar toward the fixed plate and moving forward, the movable plate moves toward the fixed plate, and the displacement sensor detects a protrusion length of the tie bar from the fixed plate. Injection compression molding equipment. 4. The injection compression molding apparatus according to claim 1, wherein said first drive mechanism also functions as said second drive mechanism, and said displacement sensor detects a displacement of a drive section of said first drive mechanism. An injection compression molding apparatus characterized by detecting.