JPH06320568A - Molding apparatus and injection molding method - Google Patents

Abstract

PURPOSE:To shorten a molding cycle and to reduce molding cost by constituting the injection filling means of a filling-relaxing station of an injection molding machine and providing a mold temp. adjusting mechanism to the die plate of the injection molding machine. CONSTITUTION:A molding apparatus has a molding system wherein a plurality of cavity units 1 having a pair of molds having cavities formed therein are successively fed to a prescribed heating station 2, a filling-relaxing station 3, a gradual cooling station 4 and a molded product taking-out station 5 to mold resin molded products having shapes corresponding to those of the cavities. In this apparatus, the injection filing machine of the filling-relaxing station is constituted of an injection molding machine and a molding temp. adjusting mechanism is provided to the die plate 8 of the injection molding machine. Therefore, a plurality of the cavity units 1 can be formed into an inexpensive simple structure having no temp. control member and, as a result, manufacturing cost can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus, and more specifically, it can be applied to a gate seal injection molding apparatus suitable for injection molding of an optical element such as a plastic lens and an injection molding method using the same. In particular, the present invention relates to a molding apparatus capable of shortening the molding cycle, reducing the die cost, and obtaining a high-quality resin molded product with less residual distortion and the like.

[0002]

2. Description of the Related Art Conventionally, in a resin molding method, as shown in FIG. 5, the mold temperature is program-controlled to inject the resin so that the fluidity of the resin is increased, and then the mold temperature is raised, followed by cooling ( It is known that there is an advantage that a molded product with a high mold copy degree can be obtained by removing the internal distortion of the molded product by quenching) and keeping the cooling rate slow near the glass transition temperature of the resin while applying pressure. Has been.

Now, plastic resin molded articles for optical parts such as lenses are required to satisfy required characteristics such as surface accuracy and internal strain.
The latter internal distortion causes disturbance of the transmitted light path, so
It is required to reduce it as much as possible.

[0004]

However, in the conventional resin molding method as described above, as shown in FIG.
In order to relax efficiently, the resin filled in the cavity after injection is heated to around the melting temperature, and after holding for a certain period of time, it enters the cooling (quick cooling) process, so the holding time becomes longer and the molding cycle becomes longer. In addition, since the rapid cooling rate is kept slow near the glass transition point of the resin (gradual cooling), pressure is applied at the same time, so a special pressurizing mechanism and slow cooling mechanism are required, which complicates the mold structure and makes the mold There was a problem that the cost increased.

Further, when an attempt is made to mold a resin molded product having an uneven thickness and an irregular shape, the thin portion solidifies quickly, so even if the moving core presses the entire molded portion, the thin portion solidifies. The resin does not move, and as a result, the thick part is not pressed and "sink marks" occur. In addition, if the thin part is forcibly pressed while it is solidified, stress is generated in the thin part and distortion occurs. was there.

Therefore, the present invention provides a molding apparatus capable of shortening the molding cycle, reducing the die cost, and obtaining a high-quality resin molded product with less residual distortion and the like. Is intended.

[0007]

The invention according to claim 1 is
A plurality of cavity units each having a pair of molds each having a cavity formed therein are conveyed to a predetermined heating station, a filling / relaxation station, a slow cooling station, and a molded product unloading station in this order, and correspond to the cavities. In a molding apparatus having a molding system for molding a resin molded article, the injection / filling means of the filling / relaxation station comprises an injection molding machine, and the die plate of the injection molding machine is provided with a mold temperature adjusting mechanism. It is characterized by that.

According to a second aspect of the present invention, in the above-mentioned first aspect of the invention, the molding system is a gate seal molding system for gate-sealing the cavity unit in which the cavity is filled with resin. It is what The invention according to claim 3 is the above-mentioned claim 1,
In the invention described in 2, a plurality of the mold temperature adjusting mechanisms are provided.

According to a fourth aspect of the present invention, in the first to third aspects of the invention, the mold temperature adjusting mechanism is formed of a heating plate made of metal. A fifth aspect of the invention is characterized in that, in the first to fourth aspects of the invention, the mold temperature adjusting mechanism uses oil as a medium.

According to a sixth aspect of the present invention, in the above first to fifth aspects, the heating means of the mold temperature adjusting mechanism is high frequency induction heating. The invention according to claim 7 is the invention according to any one of claims 1 to 5, characterized in that the heating means of the mold temperature adjusting mechanism is a resistance heater.

The invention according to claim 8 is characterized in that, in the invention according to any one of claims 1 to 7, a heating stage is provided in a conveying path immediately before the injection molding machine of the filling / relaxing station. is there. The invention described in claim 9 is a method for molding a resin molded product by an injection molding method using the molding apparatus according to any one of claims 1 to 8, wherein filling and
It is characterized in that the resin filled in the cavity at the relaxation station is once heated to the glass transition point of the resin or higher and then gradually cooled.

According to a tenth aspect of the present invention, in the method of molding a resin molded product by the injection molding method using the molding apparatus according to the first to eighth aspects, the mold temperature at the time of injection at the filling / relaxation station is controlled by the resin. After the temperature is set lower than the glass transition point temperature of, the mold temperature is raised to a temperature equal to or higher than the glass transition point of the resin at the end of relaxation.

[0013]

According to the present invention, a plurality of cavity units each having a pair of molds each having a cavity formed therein are provided with a predetermined heating station, a filling / relaxation station, a slow cooling station and a molded product unloading station. In a molding apparatus having a molding system for carrying out a resin molding in a shape corresponding to the cavity, the injection / filling means of the filling / relaxation station comprises an injection molding machine, and a die of the injection molding machine. The plate is provided with a mold temperature adjusting mechanism. Therefore, the plurality of cavity units can have a low cost and a simple structure without a temperature adjusting member, so that the manufacturing cost of the molding apparatus can be reduced.

According to a second aspect of the present invention, in the above-mentioned first aspect of the present invention, the molding system is a gate seal molding system for gate-sealing the cavity unit in which the cavity is filled with resin. There is. Therefore, since the molding system is configured as a gate seal molding system, highly accurate precision molding can be performed.

According to a third aspect of the present invention, the above-mentioned first aspect,
In the invention described in 2, the mold temperature adjusting mechanism is provided in plural. Therefore, since a plurality of mold temperature adjusting mechanisms are provided and configured, the temperature of the cavity unit can be rapidly adjusted (temperature rise). According to a fourth aspect of the invention, in the first to third aspects of the invention, the mold temperature adjusting mechanism is formed by a heating plate made of metal. Therefore, since the mold temperature adjusting mechanism is composed of a metal heating plate having good thermal conductivity, rapid heating can be performed and efficient temperature rise can be performed.

According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the mold temperature adjusting mechanism is configured to use oil as a medium. Therefore, the mechanism for bringing the heating plate into close contact with the cavity unit is a hydraulic mechanism, and the oil is used as the medium of the mold temperature adjusting mechanism, so that rust and the like can be prevented from occurring in the mold temperature adjusting mechanism.

According to a sixth aspect of the present invention, in the above-described first to fifth aspects, the heating means of the mold temperature adjusting mechanism is constituted by high frequency induction heating. Therefore, the cavity unit can be quickly heated to the target temperature. In the invention according to claim 7, the above-mentioned claim 1
In the invention described in any one of claims 1 to 5, the heating means of the mold temperature adjusting mechanism is a resistance heater. Therefore, the cavity unit can be quickly heated to the target temperature.

According to the invention described in claim 8, in the invention described in any one of claims 1 to 7, the heating stage is provided in the conveying path immediately before the injection molding machine of the filling / relaxation station. Therefore, the mold heating time can be shortened and the molding cycle can be shortened. According to a ninth aspect of the present invention, in the method of molding a resin molded article by an injection molding method using the molding apparatus according to the first to eighth aspects, the resin filled in the cavity at the filling / relaxation station is temporarily pressed. In consideration of the above, the resin is heated to a glass transition point or higher and then gradually cooled. Therefore, the fluidity of the resin can be increased, relaxation can be promoted, and a high-quality molded product with less internal strain can be obtained.

According to a tenth aspect of the present invention, in the method of molding a resin molded product by the injection molding method using the molding apparatus according to the first to eighth aspects, the mold temperature at the time of injection at the filling / relaxation station is controlled. After setting the temperature lower than the glass transition temperature of the resin, at the end of relaxation (at the start of slow cooling), the mold temperature is raised until the temperature is equal to or higher than the glass transition temperature of the resin. I am configuring. For this reason,
Therefore, it is possible to obtain a high-quality molded product with less burr and less distortion.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a molding system applied to a molding apparatus according to an embodiment of the present invention. The molding system in the illustrated example is applied to a gate seal molding system. In FIG. 1, 1 is a plurality of cavity units each having a pair of molds in which cavities are formed, 2 is a heating station for heating the cavity unit 1, and 3 is a heating station 2. Filling / relaxing the cavity unit 1
It is a relaxation station. Further, 4 is a gradual cooling station for gradually cooling the cavity unit 1 filled / relaxed in the filling / relaxation station 3, and 5 is a molded product for taking out a molded product from the cavity unit 1 gradually cooled in the gradual cooling station 4. Reference numeral 6 is a take-out station, 6 is a transfer path between the stations where the cavity unit 1 processed in each station is transferred, and 7a to 7c are heating stages provided in the heating station 2 for heating the cavity unit 1. .

Next, FIG. 2 is a diagram showing the structure of the filling / relaxation station of FIG. The filling / releasing station 3 in the illustrated example comprises a vertical injection molding machine. In FIG. 2, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts, 8 is a die plate of the injection molding machine, 9 is a mold temperature adjusting mechanism provided on the die plate 8, and this mold temperature adjusting The mechanism 9 is composed of a heating plate 10 made of metal and a resistance heater 11 provided in the heating plate 10.

Next, the molding process of this embodiment will be described. First, set the cavity unit 1 to the heating station 2
And heat the mold temperature near the cavity of the mold to 165 ° C.
Heat to. Then, the cavity unit 1
After reaching 65 ℃, 2 from the injection cylinder of the injection molding machine.
The above-mentioned PC in a molten state after being heated to 70 ° C to 300 ° C
(Polycarbonate) resin in the cavity, for example 10
High pressure filling of 00 kgf / cm ² is performed.

Then, immediately after filling (instead of maintaining the same temperature until the end of relaxation), the die plate 8 of the injection molding machine is started.
The glass transition point of the resin in consideration of the pressure by the mold temperature adjusting mechanism 9 provided in the above (however, Tg 142 ° C. of PC is not the data measured while pressurizing, but the Tg under 1 atm.
Means ) Heating to the above temperature increases the fluidity of the resin to promote relaxation sufficiently and removes internal strain.

Thereafter, the slow cooling station 4 is operated at 5 ° C. /
The product is slowly cooled to a temperature not higher than the heat distortion temperature (temperature at which it solidifies) at a cooling rate of not more than a minute, and the molded product is taken out at the molded product take-out station 5. As described above, in this embodiment, a plurality of cavity units 1 each having a pair of molds each having a cavity formed therein are provided with a predetermined heating station 2, a filling / relaxation station 3, a slow cooling station 4, and a molded product. In a molding apparatus having a molding system that conveys in order to the take-out station 5 and molds a resin molded product having a shape corresponding to the cavity, the injection / filling means of the filling / relaxation station 3 is composed of an injection molding machine, and The die plate 8 of the molding machine is provided with a mold temperature adjusting mechanism 9. Therefore, the plurality of cavity units 1 can be made into a low-cost and simple structure without a temperature adjusting member, so that the manufacturing cost of the molding apparatus can be reduced.

Further, in this embodiment, the molding system is provided with the cavity unit 1 in which the cavity is filled with resin.
It is configured as a gate seal molding system for sealing the gate. Therefore, since the molding system is configured as a gate seal molding system, highly accurate precision molding can be performed. Further, in this embodiment, a plurality of mold temperature adjusting mechanisms 9 are provided. For this reason,
Since a plurality of mold temperature adjusting mechanisms 9 are provided and configured, the temperature of the cavity unit 1 can be quickly adjusted (increased).

Further, in this embodiment, the mold temperature adjusting mechanism 9 is used.
Is formed of a heating plate made of metal. Therefore, since the mold temperature adjusting mechanism 9 is composed of the metal heating plate 10 having good thermal conductivity, rapid heating can be performed and efficient temperature rise can be performed. Further, in this embodiment, the heating means of the mold temperature adjusting mechanism 9 is constituted by the resistance heater 11. Therefore, the cavity unit can be quickly heated to the target temperature. The heating means of the mold temperature adjusting mechanism 9 may be configured by high frequency induction heating, and in this case, the same effect as that of the resistance heater 11 can be obtained.

Further, in the present embodiment, in the method of molding a resin molded product by the injection molding method, the resin filled in the cavity at the filling / relaxation station 3 is once heated to a temperature above the glass transition point of the resin in consideration of the pressure. After that, it is configured to be gradually cooled. Therefore, the fluidity of the resin can be increased, relaxation can be promoted, and a high-quality molded product with less internal strain can be obtained.

In this embodiment, in the method of molding a resin molded product by the injection molding method, after the mold temperature at the time of injection at the filling / relaxation station 3 is set lower than the glass transition temperature of the resin, At the end of the relaxation, the mold temperature in consideration of the pressure is raised to a temperature not lower than the glass transition point of the resin. Therefore, it is possible to obtain a high-quality molded product with less burr and less distortion.

In the molding method of this embodiment, as shown in FIG. 3, the injection mold temperature of the cavity unit 1 can be made lower than the injection mold temperature of 170 ° C. in the conventional cavity unit molding. FIG. 4 in comparison with the conventional one of a)
With the products (b) and (c) of the present invention, it is possible to obtain a molded product with almost no burr and little internal strain. 4 (a) to 4 (c) show the distortion improving effect of the polarizing plate, which is 165 ° C. (conventional) in FIG. 4 (a) → 170 ° C. in FIG. 4 (b) (present invention). The strain state is better than that of FIG. 4 (b), 170 ° C. (invention) → the 175 ° C. (invention) in FIG. Further, FIG. 3 shows changes in pressure and temperature during the molding process, the upper part is a time-pressure curve, and the lower part is a time-pressure curve.
It is a temperature curve.

Further, in this embodiment, the heating time by the heating station 2 can be shortened because the mold temperature at the time of injection is low. In the above embodiment, the resin used was PC, but the present invention is not limited to this, and any thermoplastic resin for optics may be used. Next, in the present invention, the mold temperature adjusting mechanism may be configured to use oil as a medium. In this case, the mechanism for bringing the heating plate into close contact with the cavity unit is a hydraulic mechanism, and the oil is used for the mold. Since it is configured as a medium of the temperature adjusting mechanism, it is possible to prevent rust and the like from occurring in the mold temperature adjusting mechanism.

Next, in the present invention, a heating stage may be provided in the conveying path immediately before the injection molding machine of the filling / relaxation station. In this case, the mold is preliminarily loaded before the mold is loaded. Since heating can be performed, the mold temperature raising time can be further shortened and the molding cycle can be further shortened.

[0032]

According to the present invention, it is possible to shorten the molding cycle, reduce the apparatus cost, and obtain a high-quality resin molded product with less residual strain. is there.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a molding system applied to a molding apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a filling / relaxation station of FIG.

FIG. 3 is a diagram showing changes in pressure and temperature during a molding process of the present invention and a conventional example.

FIG. 4 is a diagram showing a distortion improving effect of the molded product of the present invention.

FIG. 5 is a diagram showing a molding process of a conventional example.

[Explanation of symbols]

 1 Cavity Unit 2 Heating Station 3 Filling / Mitigation Station 4 Gradual Cooling Station 5 Molded Product Removal Station 6 Conveyance Path 7a to 7c Heating Stage 8 Die Plate 9 Mold Temperature Control Mechanism 10 Heating Plate 11 Resistance Heating Heater

Claims (10)

[Claims] 1. A plurality of cavity units each having a pair of molds each having a cavity formed therein are conveyed in order of a predetermined heating station, a filling / relaxation station, a slow cooling station and a molded product unloading station, and In a molding apparatus having a molding system for molding a resin molded product having a shape corresponding to the cavity, the injection filling means of the filling / relaxation station comprises an injection molding machine, and the die temperature of the injection molding machine is adjusted with a mold temperature. A molding apparatus comprising a mechanism. 2. The molding apparatus according to claim 1, wherein the molding system is a gate seal molding system for gate-sealing the cavity unit in which the cavity is filled with resin. 3. The molding apparatus according to claim 1, wherein a plurality of mold temperature adjusting mechanisms are provided. 4. The mold temperature adjusting mechanism is formed of a heating plate made of metal.
The molding apparatus described. 5. The molding apparatus according to claim 1, wherein the mold temperature adjusting mechanism uses oil as a medium. 6. The molding apparatus according to claim 1, wherein the heating means of the mold temperature adjusting mechanism is high frequency induction heating. 7. The molding apparatus according to claim 1, wherein the heating means of the mold temperature adjusting mechanism is a resistance heater. 8. The molding apparatus according to claim 1, wherein a heating stage is provided in a conveying path immediately before the injection molding machine of the filling / relaxation station. 9. A method of molding a resin molded product by an injection molding method using the molding apparatus according to any one of claims 1 to 8, wherein the resin filled in the cavity at the filling / relaxation station is once made into a glass transition point of the resin. After heating to above,
An injection molding method characterized by slow cooling. 10. A method of molding a resin molded product by an injection molding method using the molding apparatus according to any one of claims 1 to 8, wherein a mold temperature at the time of injection at a filling / relaxation station is determined from a glass transition temperature of the resin. Is set to a low temperature, and at the end of the relaxation, the mold temperature is raised to a temperature equal to or higher than the glass transition point of the resin.