JP2002166453A - Injection compression molding method for disk-shaped molding, information recording medium, and injection compression molding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection compression molding method which can perform multi-cavity molding for a plurality of disk-shaped precision moldings of uniform quality, an apparatus for the method, and the disk-shaped precision moldings. SOLUTION: A step in which pressure is applied to the movable mold core of each cavity after a mold is closed, and it is advanced to the side of a parting line; a step in which a molten resin is divided and packed through hot runners; a step in which the movable mold core is made to retreat against the pressure with the packing of the resin, and the moving position of each movable mold core is detected; a step in which a gate is closed by a cutting punch moving backward/backward toward/from the gate in the cavity; a step in which the pressure of each cavity is increased independently to a prescribed value after the gate is closed; and a step in which the moldings are demolded after the passage of a given cooling time are performed one by one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for injection compression molding of a disk-shaped molded article, and more particularly to a method and an apparatus for injection-molding a plurality of disk-shaped molded articles at a time. The present invention relates to an information recording medium obtained by processing a disk-shaped molded product obtained by a method and an apparatus.

[0002]

2. Description of the Related Art In injection molding, which is one of plastic molding methods, a high-temperature resin melted and kneaded by a molding machine is poured into a molding space (cavity) in a mold, and cooled and solidified in the mold to form a plastic. Is shaped into a predetermined shape. 2. Description of the Related Art In injection molding, in order to improve productivity, resin is injected into a plurality of cavities at a time to form a plurality of molded products at once. In such multi-cavity production, when the process of filling each cavity with resin is observed with an insufficiently filled product or observed with a visualization mold, there is variation in the filling time in each cavity, and the history of molding is Due to the difference, it was found that the packing was uneven.

[0003] With respect to disk-shaped molded products, several improved multi-cavity injection compression molding methods have been already proposed for the purpose of reducing variations in each cavity. As a specific example, for example, Japanese Patent Application Laid-Open No. 6-30498
No. 1 publication. In this method, the gate is closed by a cut punch by a time control after the resin is filled in a multi-cavity mold of a disk-shaped molded product, and compressed by a core. However, in the method of closing the gate by time control using a timer or the like, it is difficult to eliminate the influence of variations among cavities. Another specific example is described in JP-A-6-208734. In this method, a pressure sensor is provided in a mold, and when the detected value reaches a predetermined value, the gate is sealed and compressed by the core. However, the pressure in the mold often changes with time due to contamination of the inside of the mold and other parts, and therefore, it may not always be suitable as a means for determining the filling state of the resin in the mold. When a pressure sensor is provided at the rear end of the sliding part,
When the sliding resistance changes with time due to wear or lubricating oil, the detected value of the resin pressure in the mold may change.

[0004] Specific examples of a disk-shaped molded product include a CD,
Discs for optical information recording media such as MD and DVD are mentioned. In these optical information recording media, minute pits and / or grooves are transferred to the entire surface of one surface of a disk, and the other surface is formed as a flat surface. Laser light is vertically incident from this flat surface,
Changes in the amount of reflected light or transmitted light due to pits and / or grooves are converted to digital signals.
Therefore, it is important that these discs transfer minute pits and / or grooves accurately. Further, as described above, in order to read the amount of change in the reflected light or transmitted light of the laser light, it is important to improve the flatness and the thickness uniformity of the laser light incident surface. In particular, DVDs on which information is recorded at a very high density, and DVD-Rs on which information is recorded by a writer, require strict management of these. An optical information recording medium such as a DVD-R capable of recording and reproducing data on at least one of the front and back surfaces of a disk is manufactured by bonding two thin disks which have been subjected to predetermined processing. But
In this case, if the two disks to be bonded have a difference in molding conditions, uneven transfer, uneven thickness, or the like, there is a problem that the disks are peeled off or deformed due to aging after bonding. Therefore, it is necessary that the shapes and characteristics of these two disks be as uniform and identical as possible. However, a disk-shaped molded product that satisfies these requirements has not been achieved by the conventional multi-cavity technology. For this reason, it has been necessary to newly develop a precise multi-cavity molding method with very little variation.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to eliminate the disadvantages of conventional multi-cavity molding of a disk-shaped molded product. It is an object of the present invention to provide an injection compression molding method and apparatus capable of obtaining a large number of uniform disk-shaped molded products with little variation at a time, and a disk-shaped molded product. In addition, by using a single-piece high-precision disk-shaped molded product, which was conventionally a single-piece product, it is necessary to use only one set of molding machine and a mold for a series of production lines, thus simplifying the production line. It is an object of the present invention to provide an injection compression molding method and an apparatus which can also achieve simplification and easy adjustment of molding tact.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide a molding method for taking a large number of disk-shaped molded articles by an injection compression molding apparatus having a plurality of cavities in one mold; Applying a predetermined pressure to the movable mold cores of the cavities in advance and causing them to advance to the parting line; and diverting the molten resin into the cavities through hot runners provided for the respective cavities. A step of initiating a filling operation; a step of retracting the movable core against the pressure with the filling of the resin, and individually detecting a moving position of each movable core at that time; When the position is reached, the operation of completely closing the gate with a cut punch that moves forward and backward in the cavity toward the gate is performed independently for each cavity. And; after the gate closes,
Performing the operation of moving the tip of the movable core into the cavity and increasing the pressure in the cavity to a predetermined value independently for each cavity; and removing the molded product after a certain cooling time has been sequentially performed; The injection compression molding method for a disk-shaped molded article can be achieved.

Still another object of the present invention is to provide a molding method for taking a large number of disk-shaped molded articles by using an injection compression molding apparatus having a plurality of cavities in a single mold; Setting the movable core at a position where a larger amount of resin than the specified amount is filled into the cavity; and filling the cavity by splitting and flowing the molten resin through a hot runner provided for each cavity; After the cavity is filled with a larger amount of resin than the specified amount, each movable core is advanced into the cavity, a part of the resin in the cavity is caused to flow backward through the gate, and the moving position of each movable core at that time is determined. Individually detecting; when the movable core reaches a predetermined position, the gate is completed by a cut punch that moves forward and backward in the cavity toward the gate. Performing a completely closing operation independently for each cavity; after the gate is closed,
The step of independently moving the tip of the movable mold core further into the cavity and increasing the pressure in the cavity to a predetermined value for each cavity; and the step of taking out a molded article after a certain cooling time has elapsed. It can be achieved by a method of injection-compression molding of a disk-shaped molded product, characterized in that it is performed.

[0008] Further, the above method comprises: a movable mold and a fixed mold configured to form a plurality of cavities having a shape corresponding to a desired disk-shaped molded product when the mold is closed; A plurality of hot runners provided for each cavity in a fixed mold so that the molten resin extruded from the injection nozzle is divided and filled into the plurality of cavities at the same time; A plurality of movable cores provided for each cavity in the movable mold so as to increase the pressure of the molten resin filled in the cavity; and a position of the movable core for individually detecting a filling state of the resin in each cavity. And a cut punch that moves back and forth toward the gate inside the cavity to open and close the gate; A control device for controlling a supply operation of a molten resin, an opening / closing operation of a plurality of gates, and an advance / retreat operation of a movable mold core; it can.

In this case, the control by the control device is such that after closing the mold, a predetermined pressure is applied to the movable mold cores of the cavities in advance, and the movable cores are advanced toward the parting line. While filling the molten resin from each hot runner, the position of each movable core is individually detected by the sensor, and for the cavity where the movable core has reached a predetermined position, the cut punch is operated to open the gate. After completely closing, the movable core is advanced into the cavity, the operation of increasing the pressure in the cavity to a predetermined value is performed independently for each cavity, and the operation of taking out the molded product after a certain cooling time has been sequentially performed. It is configured as follows.

[0010] Alternatively, the control by the control device may include:
After closing the mold, with the movable mold core set at a position where a larger amount of resin than the specified amount is filled into each cavity,
Dividing and filling the molten resin through each hot runner into each cavity, and after filling each cavity with a larger amount of resin than a prescribed amount, each movable mold core is advanced into the cavity, and the resin in the cavity is filled with resin. A part of the flow is returned through the gate, and the moving position of each movable core at that time is individually detected.For the cavity where the movable core has reached a predetermined position, the cut punch is operated to completely close the gate. After that, the movable core is further advanced into the cavity, the operation of increasing the pressure in the cavity to a predetermined value is performed independently for each cavity, and the operation of taking out the molded product after a certain cooling time has been performed is sequentially performed. Is done.

The position sensor used in the injection compression molding has a resolution B (unit: mm); a thickness of a molded product to be manufactured is t (unit: mm); and a required thickness variation is A ( When the unit is set to be equal to or less than B, B ≦ (A ·
It is desirable to satisfy the relational expression of t) / 200.

The positioning mechanism for stopping the cut punch at its most advanced position is provided on the drive unit of the cut punch so that the driving force of the cut punch is not transmitted to the movable core and / or the movable die. It is desirable.
Further, it is desirable that the clearance between the cut punch and the drive shaft of the drive device is 0.1 mm or less. Gate cut force Pg by the above cut punch
It is desirable to satisfy the relational expression of [Pg / (pi · A)] ≧ 1.1, where A is the cross-sectional area perpendicular to the axis at the tip of the cut punch, and pi is the injection resin pressure.

Another object of the present invention is to provide a disk-shaped molded product obtained by the above-mentioned method, after subjecting the disk-shaped molded product to a required process known in the art, and forming two disk-shaped products in the same mold. This is achieved by an information recording medium obtained by laminating molded articles, particularly an optical information recording medium.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic view showing a main part of an embodiment of an injection compression molding apparatus according to the present invention for performing an injection compression molding method according to the present invention in a first stage in which a cavity is filled with a molten resin. FIG. 2 is a schematic sectional view showing the second stage; FIG. 3 is a schematic sectional view showing the third stage; FIG. 4 is an example of a control device provided in the injection compression molding apparatus according to the present invention. FIG. 5 is an explanatory diagram showing
FIG. 6 is an explanatory view showing step by step details of an operation of filling a cavity with a molten resin in the present invention; FIG. 6 is an example of a timing chart in a case where injection compression molding is performed according to the operation shown in FIG. 5; FIG. 8 is an explanatory view showing step by step details of another embodiment of the operation of filling the cavity with the molten resin in the present invention; FIG. 8 is an example of a timing chart when performing injection compression molding according to the operation shown in FIG. 7; FIG.
FIG. 10 is a cross-sectional view showing an embodiment of the configuration of the movable core position detecting means and the cut punch driving mechanism of the injection compression molding apparatus according to the present invention; FIG. FIG. 11 is a graph showing a pressure change in each cavity in the prior art;
FIG. 12 is a graph showing the variation of the core position between the cavities in the present invention in which the operation of filling the molten resin into the cavity is performed by controlling the position of the movable core; FIG. 5 is a graph showing variations in the core position between cavities in a conventional technique configured to perform a resin filling operation by time control using a timer.

In the embodiment shown in FIGS.
A and 1B are cavities, 2 is a movable mold, 20 is a movable platen, 3 is a fixed mold, 30 is a fixed platen, 4
Is an injection nozzle, 5A and 5B are movable cores respectively provided for the cavities 1A and 1B, 50A and 50B are cylinders for driving the movable cores 5A and 5B, 6A and
6B is a position sensor for detecting the position of the movable core, 7 is a control device for controlling the operation of the entire mold apparatus, 8A and 8B are gates, 9A and 9B are cut punches for sealing the gates 8A and 8B, 90A , 90B is cut punch 9
Cylinder for driving A, 9B, 10A, 10B
Is a hot runner that supplies molten resin to the cavities 1A and 1B, and PL is a parting line between the movable mold 2 and the fixed mold 3. In FIG. 4 showing the configuration of the control device 7, 7a is an input signal processor, 71 is its process card, 72 is an I / O card,
7b is a control output signal transmission processor, 73 is its process card, and 74 is an I / O card. 6A, 6B
Is the position sensor, and 50A and 50B are
The cylinders 90A and 90B for driving the movable cores 5A and 5B are the cylinders for driving the cut punches 9A and 9B.

The features of the injection compression molding apparatus shown in FIGS. 1 to 3 are as follows: (1) Since the molten resin filled in the cavities 1A and 1B is independently pressurized, the movable mold 2 is independently formed. The movable cores 5A and 5B that can be controlled are provided; (2) The movable cores are individually detected to detect the filling state of the molten resin in the cavities 1A and 1B, and based on this, the gate sealing operation and the like are controlled. Position sensors 6A and 6B capable of individually detecting the positions of 5A and 5B are provided; (3) Cut punch 9A which advances and retreats toward the gate in the cavity as means for individually opening and closing gates 8A and 8B. (4) The filling of the molten resin into the cavities 1A and 1B is started, and thereafter, the movable core 5 is moved by the position sensors 6A and 6B.
When the movable core reaches a predetermined position while detecting the positions of A and 5B, the cut punches 9A and 9B are operated to close the gates 8A and 8B individually to stop filling the molten resin. And a control device 7 for automatically performing a series of operations of independently pressing the movable cores 5A and 5B to pressurize the resin in the cavities 1A and 1B; and so on.

When the injection compression molding is performed by the apparatus shown in FIGS. 1 to 3, first, the melt-plasticized resin is divided by the injection molding machine from the injection nozzle 4 into the fixed mold 3 in the divided direction. Each hot runner 10 through roads 3a and 3b
A, 10B, divided into gates 8 at the tip of each runner
A and 8B are filled into the cavities 1A and 1B (see FIG. 1).

At this time, as will be described later in detail with reference to FIG. 5, prior to filling the molten resin, the movable cores 5A, 5B
A predetermined pressure P1 is applied to the movable cores 5A and 5A in advance.
In a state where B has been advanced to the parting line PL side, resin filling is started. The cavities 1A and 1B are gradually filled with resin, and when the cavity internal pressure becomes equal to or higher than the above P1, the movable side cores 5A and 5B gradually retreat by the pressure. The positions of the movable cores 5A, 5B are detected by position sensors 6A, 6B provided for the respective movable cores, and the outputs are provided to the control device 7.

First, the cavity 1A is completely filled,
When the position sensor 6A detects that the movable core 5A has retracted to a predetermined position, a signal is sent from the control device 7 to the drive cylinder 90A of the cut punch 9A of the cavity 1A, as shown in FIG. To
The cut punch 9A is advanced to the gate 8A side and the gate 8
A is completely closed. Next, a signal is sent to the driving cylinder 50A of the movable core 5A to operate it, the movable core 5A is advanced toward the cavity 1A, and the molten resin in the cavity is compressed to thereby reduce the pressure in the cavity. At the same time as making the distribution uniform, the resin is compressed until the resin pressure in the cavity 1A reaches a predetermined value. At this time, the scanning time of each detection value for controlling the movable core and the cut punch is 2 ms or less, preferably 1 ms.
ec or less, more preferably 500 μsec or less.

Next, the cavity 1B is completely filled,
When the position sensor 6B detects that the movable core 5B has retracted to a predetermined position, a signal is sent from the control device 7 to the drive cylinder 90B of the cut punch 9B of the cavity 1B in the same manner as described above. As shown in FIG. 3, the cut punch 9B is moved to the gate 8B side to completely close the gate 8B, and the movable core 5B is advanced toward the cavity 1B to compress the molten resin in the cavity. Thereby, the pressure distribution in the cavity is made uniform, and the resin is compressed until the resin pressure in the cavity 1B reaches a predetermined value.

In the present invention, since these operations are performed independently for each of the cavities 1A and 1B, the change in pressure generated between the cavities 1A and 1B can be made the same. That is, FIG. 10 shows changes in the pressures of the cavities 1A and 1B. As shown in this graph, according to the present invention, the maximum pressure of both cavities and the holding time thereof can be made equal. By pressurizing the resin for a certain period of time and cooling the resin by the mold, the resin is solidified, and a highly accurate disk-shaped molded product having no variation in shape and other characteristics can be obtained. On the other hand, in the prior art, since the cavities 1A and 1B are simultaneously compressed, as shown in FIG.
Is reduced without reaching the maximum pressure of the cavity 1A, so that the shrinkage after molding is
, Resulting in dimensional variations in the final product.

Further, in the present invention, the state of filling the cavity with the resin is determined based on the position of the movable core, and the filling of the resin is stopped (gate seal) based on the position data of the movable core. As a result, the variation in the amount of filling resin between the cavities is significantly reduced as compared with the conventional case where the gate seal is performed by timer control. That is, FIG. 12 shows the variation of the core stop position when the gate seal is completed when the gate seal is performed based on the position of the movable core according to the present invention. In this case, the weight variation of the filling resin was 1.5%. On the other hand, FIG. 13 shows the variation of the core stop position at the completion of the gate seal in the case where the timer control of uniformly performing the gate seal after the elapse of a predetermined time from the start of the filling is performed according to the related art.
It is shown that the weight variation of the filling resin in this case is 6.6%. Compared to this variation,
It can be understood that the variation of the present invention 2 is very small. In the present invention, a molded product having a small variation is subjected to a known process, for example, a process of forming a reflective film or an adhesive layer, and then molded using the same mold to maintain the same. This is for manufacturing an information recording medium, particularly an optical information recording medium, by laminating two sheets. Therefore, it can be understood that the present invention is particularly suitable for molding an optical information recording medium such as a CD-R, a DVD, and a DVD-R, which require high precision.

Further, in the present invention, the determination of the filling state of the resin in the cavity is performed not based on the pressure in the cavity but on the position of the movable core, so that more accurate control is possible. That is, when the filling state of the resin is determined based on the pressure in the cavity, the detected value of the pressure often changes with time due to contamination of the inside of the mold and other parts. For example, when a pressure sensor is provided at the rear end of the sliding portion of the movable core, the detection value of the resin pressure in the cavity changes as the sliding resistance changes with time due to wear and lubricating oil. If the pressure sensor is installed directly in the cavity, the molded product will have a trace of the sensor,
Also, the detected value of the pressure may be different due to a slight difference in the position where the sensor is provided. On the other hand, if the filling state of the resin in the cavity is determined based on the position of the movable mold core as in the present invention, accurate control of the gate seal, the compression operation, and the like can be performed.

In the embodiment shown in FIGS. 1 to 3, the number of cavities is increased, but the number of cavities and the number of movable cores and cut punches corresponding thereto are increased to further increase the number of cavities. be able to.

Here, the filling operation of the molten resin into each cavity will be described in more detail with reference to FIG.
In FIG. 5, the operation of filling the resin into one cavity 1A is shown in steps, but the same operation as that of the cavity 1A is performed separately and independently for the other cavities as described above. FIG. 6 shows a timing chart when injection compression molding is performed according to the operation method shown in FIG.

First, at a stage before injection, a predetermined pressure P1 is applied to the movable core 5A in advance, and the movable core 5A is advanced to the parting line PL side. ), The hot runner 10A
, The filling of the resin into the cavity 1A is started.

The resin is gradually filled in the cavity 1A, and when the pressure in the cavity becomes equal to or higher than the pressure P1, the movable core 5A is gradually retracted by the pressure as shown in FIG. 5 (b). The position of the movable core 5A at that time is detected by a position sensor 6A comprising a magnescale 61a attached to the side surface of the movable core 5A and its read head 62a, and the resin is filled. When the movable core 5A continues to retreat and its tip 5A-1 reaches a predetermined position c as shown in FIG. 5C (that is, a predetermined amount of resin necessary for a molded product is in the cavity). When it is filled), this is detected based on the output of the position sensor 6A, a signal is sent from the control device 7 to the drive cylinder 90A of the cut punch 9A, and the cut punch 9A is pushed out to close the runner gate. At this time, the magnitude of the force Pg to be applied to the cut punch 9A will be described later with reference to FIG.

As the position sensor 6A, any suitable known means such as a limit switch can be used in addition to the above structure. Resolution of position sensor is 5
μm or less, preferably 1 μm or less, more preferably 0.1 μm or less.
It is recommended to use one of 5 μm or less. The sampling time of the detected value of the position sensor is 1 msec.
Or less, preferably 50 μsec or less, more preferably 2 μsec or less.
5 μm or less. At this time, the scanning time of each detection value for controlling the movable core and the cut punch is set to 2 msec or less, preferably 1 msec or less, and more preferably 500 μsec or less.

After closing the gate, pressure P2 is applied to the movable core 5A as shown in FIG.
Is applied to cool and solidify the resin in the cavity while the resin pressure in the cavity is increased. The above operation is performed independently for each cavity, and when the resin in all the cavities has solidified, the mold is opened and the molded product is taken out.

Next, the resin filling operation shown in FIG. 7 will be described. FIG. 8 shows an example of a timing chart at this time. As shown in FIG. 7A, the movable mold core 5A is retracted in advance to a position d larger than the prescribed position c of the amount of resin required for the molded product. By filling the resin in this state, as shown in FIG. 7B, the cavity is filled with a larger amount of resin than a prescribed amount required for the molded product. Next, as shown in FIG. 7C, while the runner gate is kept open, a force P3 for overcoming the injection pressure from the hot runner is applied to the movable core 5A to apply the force to the movable core 5A.
By extruding A into the cavity, a part of the resin filled in the cavity flows back to the hot runner through the runner gate. By this backflow operation, the pressure distribution in the cavity can be made uniform. In addition,
If the cavity is overfilled with resin, an excessive pressure is generated. Therefore, the cavity may be filled slightly more than the specified position c, and the movable core 5A may be pushed back into the cavity and flow backward.

In the process of pushing the movable core 5A back into the cavity in this way, when the resin in the cavity reaches a specified amount as shown in FIG. At this point, this is detected, and the cut punch 9A is pushed out to close the runner gate. After the gate is closed, in order to perform compression molding, a force P2 is applied to the movable mold core 5A as shown in FIG. 7 (e) to cool and solidify the resin in the cavity while the resin pressure in the cavity is increased. Let it. Perform the above operation independently for each cavity, and when the resin in all cavities has solidified,
Open the mold and remove the molded product.

Finally, referring to FIG. 9, the most advanced positioning means of the cut punch 9A, the resolution of the position sensor 6A, and the like will be supplementarily described. First, the most advanced positioning means of the cut punch 9A will be described. In a molding apparatus using a movable mold core, the cavity internal pressure P is controlled by a mold clamping pressure Pc. That is, a relationship of “cavity pressure P = mold clamping pressure Pc” is established. In this case, if the most advanced positioning means of the cut punch 9A is provided in the movable mold 2 or the movable core 5A,
The forward pressure of A directly acts on the movable mold 2 and the movable core 5A, which changes the mold clamping pressure Pc and changes the cavity internal pressure P, which is not preferable. Therefore, the above problem can be solved by providing the most advanced positioning means of the cut punch 9A in the drive cylinder 90A of the cut punch. This will be described with reference to FIG. 9. In FIG. 9, 90A is a cylinder for driving a cut punch, 91a is its piston, 91b is a drive shaft, 91c is a positioning sleeve, 91d is an accessory jacket, and 91e is a positioning cylinder. It is a restraining surface. In the illustrated state, the right end surface of the drive shaft 91b is in contact with the left end surface of the cut punch 9A, and the drive shaft 91a
Is driven rightward, the cut punch 9A is advanced rightward, and the runner gate is sealed at the most advanced position. Therefore, in the most advanced position, the positioning sleeve 91 of the drive shaft 91b is set.
By making the configuration such that c is in contact with the restraining surface 91e of the attached jacket 91d, the drive shaft 91b is prevented from advancing, whereby the most advanced positioning of the cut punch 9A is performed. If such a positioning means is provided, for example, between the movable core 5A and the cut punch 9A, the forward force of the cut punch 9A directly acts on the movable core 5A to change the cavity internal pressure. ,
This can be avoided by providing positioning means on the side of the cylinder 90A as shown.

Next, the clearance between the right end surface of the drive shaft 91b and the left end surface of the cut punch 9A (both are in contact in the illustrated state and the clearance is zero) will be described. If there is a clearance between the right end face of the drive shaft 91b and the left end face of the cut punch 9A when operating the cylinder 90A to perform the gate seal, a gate cut signal is sent to the cylinder 90A, and the cylinder 90A Causes a time lag between the start of the operation and the actual movement of the cut punch 9A. Then, resin is filled in the cavity 1A, and the cut punch 9
It is most preferable that the left end face of the cut punch 9A comes into contact with the right end face of the drive shaft 91b so that the clearance becomes zero when A retreats.
It is desirable to suppress the clearance to about 0.1 mm.

Next, the gate cutting force Pg by the cut punch 9A will be described. The gate cutting force Pg must be greater than the force that the cut punch 9A receives due to the resin filling pressure. That is, as shown in FIG. 9C, when the sectional area perpendicular to the axis at the tip of the cut punch 9A is A and the resin pressure is pi, unless Pg> pi · A, the cut punch 9A cannot move forward. In order for the cut punch 9A to advance smoothly and perform a stable gate cut, it is preferable that [Pg / (pi · A)] ≧ 1.1. For example, pi = 25 to 45 MPa
(Pressure holding step) When A = 4.91 cm <2> (diameter 25 mm), for example, Pg = 1230 kgf may be set so that [Pg / (pi.A)] = 1.2.

Next, the resolution of the position sensor 6A required to keep the thickness variation of the molded product within a predetermined range will be described. For example, if the resolution of the position sensor is 1
If it is 0 μm, it will be 1
Since an error of 0 μm occurs, the thickness variation of the molded product is (10 × 2) μm. Therefore, the resolution of the position sensor is B (mm), and the thickness of the obtained molded product is t (m).
m), and if the variation in the thickness is A (%), to suppress the variation to A (%) or less, (B / t) × 10
0 × 2 ≦ A must be satisfied. From this equation, for the resolution B of the position sensor, B ≦ (A · t)
/ 200 is derived. As an example,
A molded product having a thickness of t = 1.27 mm is used to obtain a thickness variation A = 1.
%, The resolution B of the position sensor required when manufacturing at a ratio of less than or equal to
7) /200=0.064 (mm) = 64 (μm), and it is necessary to use a position sensor having a resolution B of 64 μm or less. As described above, the resolution required for the position sensor is determined from the thickness variation accuracy required for the molded article to be manufactured. Similarly, repeatability is required.

According to the present invention having the above-described configuration, when a large number of disk-shaped molded products are taken, extremely high precision molding can be performed. When the quality of the molded product is evaluated based on the weight variation of the product for each type of control method, the following is obtained. 1) ×: A method in which the resin filling state in the cavity is not detected (no individual control). 2) ○: A method of detecting the filling state by the pressure in the cavity (individual control based on pressure). 3) ◎: A method of detecting the resin filling state based on the position of the movable core (individual control based on the position). When compared by the above three methods, there is a large variation in the properties such as the density of the molded article in the order of X >> O >> ◎. Rather than performing molding without detecting the resin filling state in the cavity, a method of detecting and controlling the resin filling state based on the pressure in the cavity is preferable, and further detecting and controlling the position of the movable mold core. The method is preferred.

[0037]

According to the present invention, the state of resin filling in the cavities is individually detected from the position of the movable core, the gates are individually closed based on this, and the cavities are individually compressed. Since molding is performed, there is no delay in the resin injection operation due to the control operation of the adjustment valve in the runner section, etc. An injection compression molding method and apparatus that can be performed can be provided. It should be noted that the present invention is not limited to the above embodiments, but encompasses all modified embodiments that can be easily conceived by those skilled in the art from the above description within the scope of the object.

[Brief description of the drawings]

FIG. 1 shows a main part of one embodiment of an injection compression molding apparatus according to the present invention for carrying out an injection compression molding method according to the present invention;
FIG. 3 is a schematic cross-sectional view showing a first stage in which the cavity is filled with a molten resin.

FIG. 2 is a schematic sectional view showing a second stage.

FIG. 3 is a schematic sectional view showing a third stage.

FIG. 4 is an explanatory view showing an example of a control device provided in the injection compression molding apparatus according to the present invention.

FIG. 5 is an explanatory diagram showing step by step the details of one embodiment of the operation of filling a cavity with a molten resin in the present invention.

FIG. 6 is an example of a timing chart when performing injection compression molding according to the operation shown in FIG. 5;

FIG. 7 is an explanatory diagram showing stepwise details of another embodiment of the operation of filling the cavity with the molten resin in the present invention.

FIG. 8 is an example of a timing chart when performing injection compression molding according to the operation shown in FIG. 7;

FIG. 9 is a cross-sectional view showing an embodiment of the configuration of the movable core position detecting means and the cut punch driving mechanism of the injection compression molding apparatus according to the present invention.

FIG. 10 is a graph showing a pressure change in each cavity according to the present invention.

FIG. 11 is a graph showing a pressure change in each cavity according to the related art.

FIG. 12 is a graph showing a variation in core position between cavities in the present invention configured to perform a filling operation of a molten resin into a cavity by controlling a position of a movable core.

FIG. 13 is a graph showing variations in the core position between the cavities in the related art in which the filling operation of the molten resin into the cavities is performed by time control using a timer.

[Explanation of symbols]

 1A, 1B Cavity 2 Movable mold 20 Movable platen 3 Fixed mold 30 Fixed platen 3a, 3b Dividing channel 4 Injection nozzle 5A, 5B Movable core 50A, 50B Movable core driving cylinder 6A, 6B Position sensor 61a Magnescale 62a Read head 7 Controller 7a Input signal processing processor 7b Output signal transmission processor for control 8A, 8B Gate 9A, 9B Cut punch 90A, 90B Cylinder for cut punch drive 10A, 10B Hot runner PL Parting line

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideto Ogasawara 2-1-1 Tangodori, Minami-ku, Nagoya-shi, Aichi Prefecture Inside Mitsui Chemicals, Inc. (72) Inventor Mitsuharu Mikawa 2-1-1 Tangodori, Minami-ku, Nagoya-shi, Aichi Prefecture Address F-term in Mitsui Chemicals, Inc. (reference) 4F202 AH38 AH79 AP03 AP06 AR03 AR07 CA11 CB01 CK03 CK18 CK35 CK52 CK89 CN05 4F206 AH38 AH79 AP03 AP06 AR03 AR07 JA03 JL02 JN14 JN17 JN33 JN43 JP11 JQ81 5D121 DD

Claims (12)

[Claims] A plurality of cavities (1A, 1A) are provided in one mold.
1B) in a molding method in which a large number of disk-shaped molded articles are taken by an injection compression molding apparatus provided with a mold (2, 3)
After closing the movable cores (5A, 5A)
B) applying a predetermined pressure (P1) in advance to make them advance toward the parting line (PL); hot runners provided for each cavity in the cavities (1A, 1B) (10A, 10
Starting the operation of splitting and filling the molten resin through B); with the filling of the resin, the movable cores (5A, 5B) are retracted against the pressure (P1), and each movable core at that time is retreated. Individually detecting the movement position of (5A, 5B); when the movable core (5A, 5B) reaches a predetermined position (c), the cut punch (9A) which moves forward and backward toward the gate in the cavity. , 9B) to perform the operation of completely closing the gate independently for each cavity; after the gate is closed, the movable core (5A, 5B) is closed.
(B) making the tip advance into the cavity and increasing the pressure in the cavity to a predetermined value independently for each cavity; and taking out a molded article after a certain cooling time has elapsed. An injection compression molding method for a disk-shaped molded product. 2. A plurality of cavities (1A, 1A,
1B) in a molding method in which a large number of disk-shaped molded articles are taken by an injection compression molding apparatus provided with a mold (2, 3)
Closing the movable core (5A, 5B) at a position (d) where a larger amount of resin than the prescribed amount is filled into each cavity; and each cavity in the cavity (1A, 1B). Hot runner (1
0A, 10B) to separate and fill the molten resin; after each cavity is filled with a larger amount of resin than a specified amount, each movable core (5A, 5B) is advanced into the cavity, and A part of the resin flows backward through the gate, and each movable core (5
(A, 5B) individually detecting a moving position; and when the movable core (5A, 5B) reaches a predetermined position (c), the cut punch (9A, 5A) moves back and forth toward the gate in the cavity. 9B) performing an operation of completely closing the gate for each cavity independently for each cavity; after the gate is closed, the tips of the movable cores (5A, 5B) are further advanced into the cavity, and the pressure in the cavity is adjusted to a predetermined value. A step of independently performing an operation of increasing the value to a value for each cavity; and a step of removing a molded product after a predetermined cooling time has elapsed. 3. The injection compression molding method for a disk-shaped molded product according to claim 1, wherein the disk-shaped molded product is a disk for an optical information recording medium. 4. A disk-shaped molded article injection-molded in the same mold by the injection compression molding method according to claim 1 is subjected to required processing, and then two sheets are laminated. An information recording medium that is combined. 5. The information recording medium according to claim 4, which is an optical information recording medium. 6. When the mold is closed, a plurality of cavities (1A, 1A) having a shape corresponding to a desired disk-shaped molded product are provided.
A movable mold (2) and a fixed mold (3) configured to form a plurality of cavities (1A, 1A);
A plurality of hot runners (10) provided for each cavity in the fixed mold (3) so as to simultaneously fill the B).
A, 10B); a plurality of movable mold cores (5A, 5B) provided for each cavity in the movable mold so as to increase the pressure of the molten resin filled in the cavity by advancing into the cavity. The movable core (5) to individually detect the filling state of the resin in each cavity.
Sensors (6A, 6B) for determining the positions of the movable cores (A, 5B); cut punches (9A, 9B) that move back and forth toward the gate in the cavity to open and close the gate.
And a control device (7) for controlling the opening and closing operation of the mold, the supplying operation of the molten resin from the injection nozzle, the opening and closing operation of a plurality of gates, and the advancing and retreating operation of the movable core. Injection compression molding equipment for molded products. 7. The control by the control device (7) is to apply a predetermined pressure (P1) to the movable mold cores (5A, 5B) of the respective cavities in advance after closing the molds (2, 3). In a state where the resin is advanced to the parting line (PL) side, each cavity is filled with the molten resin from each hot runner (10A, 10B) while being moved by the sensor (6A, 6B). The positions of the mold cores (5A, 5B) are individually detected, and the movable mold core (5A, 5B) is detected.
A, 5B) reaches the predetermined position (c), the gate is completely closed by operating the cut punches (9A, 9B), and then the movable cores (5A, 5B).
Into the cavities, the operation of increasing the pressure in the cavities to a predetermined value is performed independently for each cavity, and the operation of taking out the molded product after a certain cooling time has been performed is sequentially performed; The injection compression molding apparatus for a disk-shaped molded product according to claim 6. 8. The control device (7) controls the movable core (5) at a position (d) in which each cavity is filled with a larger amount of resin than a specified amount after closing the molds (2, 3).
A, 5B), each cavity (1A, 5A)
1B), each hot runner (10A, 10
B), the molten resin is divided and filled, and after each cavity is filled with a larger amount of resin than a specified amount, each movable core (5A, 5B) is advanced into the cavity, and one of the resin in the cavity is removed. The part is caused to flow backward through the gate, and the moving position of each movable core (5A, 5B) at that time is individually detected. For the cavity in which the movable core (5A, 5B) has reached the predetermined position (c), After the gates are completely closed by operating the cut punches (9A, 9B), the movable cores (5A, 5B) are further advanced into the cavities to increase the pressure in the cavities to a predetermined value. 7. The injection compression molding apparatus for a disk-shaped molded product according to claim 6, wherein the operation is performed independently and the operation of taking out the molded product after a lapse of a predetermined cooling time is sequentially performed. 9. The resolution B of the position sensor (6A)
(Unit: mm); the thickness of the molded article to be manufactured is t (unit: mm), and the required thickness variation is A (unit:%).
The injection compression molding apparatus according to claim 6, wherein a relational expression of B ≦ (A · t) / 200 is satisfied when: 10. A positioning mechanism for stopping the cut punch (9A) at its most advanced position is provided on the cut punch driving device (90A) side, and the driving force of the cut punch is movable movable core (5A) and / or The injection compression molding apparatus according to any one of claims 6 to 9, wherein the injection compression molding apparatus is configured not to be transmitted to the movable mold (2). 11. The apparatus according to claim 6, wherein a clearance between the cut punch (9A) and a drive shaft (91b) of the drive device (90A) is 0.1 mm or less. Injection compression molding equipment. 12. When the gate cutting force Pg of the cut punch (9A) is A, the sectional area perpendicular to the axis at the tip of the cut punch (9A) is A, and the injection resin pressure is pi, [Pg /
(Pi · A)] ≧ 1.1 is satisfied.
The injection compression molding apparatus according to any one of the preceding claims.