JPS59232835A - Metallic mold for injection compression molding and molding method using the same - Google Patents

Abstract

PURPOSE:To mold a precision article having high surface accuracy and dimensional accuracy and free from stress cracking of the surface or delamination of a surface layer, by controlling the temperatures of a fixed mold, a movable mold and mold pieces in accordance with a prescribed pattern on the basis of an output from a temperature-detecting means for the mold pieces. CONSTITUTION:In a dwelling step of an injection molding machine, the resin in a cavity 10 is preformed by exerting a compressing force thereto by a pressure cylinder 14, and simultaneously, the degree of close contact between the resin and a fixed mold piece 1 and a movable mold piece 5 is enhanced to ensure that heat is sufficiently transferred between the resin in the cavity 10 and the mold pieces. Then, heaters 11 for the fixed mold 3 and the movable mold 9 are operated, or a heating medium is introduced into a medium passage 13, whereby the temperature of the mold pieces 1, 5 is raised to a temperature of not lower than the thermal deformation temperature of the resin to melt only the surface layer of the resin in the cavity 10, followed by re-compression and cooling simultaneously. In compression, a controlling signal is fed from a temperature controller 15 to an oil pressure controller 16 on the basis of the temperature detected by temperature sensors 12 inserted into the mold pieces 1, 5.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to injection compression molded metal and a molding method using the metal. This article relates to injection compression molded metal and its molding method, which is used to mold molded products that require the following.

[Background]

Figure 4 is a cross-sectional view of a conventional injection compression molding mold used for molding plastic lenses, and Figure 1 is a pattern diagram showing changes in pressure and temperature over time when a conventional injection compression molding mold is used. It is.

In the figure, reference numeral 1 denotes a fixed insert piece that together with a movable insert piece 5 constitutes a lens cavity, and 2 a fixed sleeve provided between the fixed insert piece 1 and the fixed mold 3.

The fixing sleeve 2 does not directly fix the fixed insert piece 1 to the fixed grip 3, but is provided so as to be able to accommodate changes in the outer diameter of the fixed insert piece 1 to some extent. Note that the fixing sleeve 2 does not necessarily need to be provided.

4 is a fixed mold mounting plate for fixing the fixed mold 3 to a molding machine (not shown). Reference numeral 6 denotes a pressure block that supports the movable inserting piece 5 from the rear and at the same time transmits the pressing force generated by the pressure cylinder 14 to the movable inserting piece 5.

Reference numeral 7 denotes a push-out plate that supports the pressure block 6 and the Z-bin 1B to be described later and transmits the pressurizing force, and 8 indicates a movable sleeve provided between the movable insert piece 5 and the movable die 9. It is. The movable sleeve 8, like the fixed sleeve 2,
9 are provided so as to be able to cope with changes in the outer diameter of the movable insert piece 5 to some extent. Moreover, the two movable insert pieces 5 in the movable sleeve 8 slide. Note that the movable sleeve 8 does not necessarily need to be provided.

9 is a movable mold for fixing the movable sleeve 8; 10 is a (lens) cavity formed by the fixed insert piece 1, the movable insert piece 5h and the movable sleeve 8; l3 is a heating and cooling medium for the temperature adjustment reservoir; aisle, 14
applies compressive force to the resin in the cavity 10 via the extrusion plate 7, pressure block 6 and movable insert piece 5, and
There are seven pressure cylinders that push out the resin in the cavity 10 at the end of the cycle.

Reference numeral 16 denotes a hydraulic control device that generates hydraulic pressure by itself and controls the hydraulic pressure sent to the pressurizing cylinder 14 under the control of appropriate control means such as a timer (not shown).

Reference numeral 17 denotes a movable part mounting plate 18 for supporting the pressure cylinder l4 and for attaching the movable fox 9 to a molding machine (not shown).
19 is a Z pin for pulling out the resin in the sprue 19 toward the JJ mold 9 side at the end of molding.

Reference numeral 20 denotes a sprue and a resin that constitute a resin passage leading from the molding machine to the cavity IO.

Conventionally, in an injection compression molding mold having the above-mentioned configuration for molding a plastic lens or the like, resin injected from an injection molding machine (not shown) is injected into the cavity lo, as shown in Fig. 1. (injection pressure p+), a holding pressure P2 is applied to the inside of the cavity 10, and from time t2 when this holding pressure P2 ends, a compressive force P3 to the cavity 10 is applied.
This was maintained until t when molding was completed.

The temperature of the molding die was maintained at a constant temperature T1 from t when injection started until time t2 when pressure retention ended, and then cooling was performed until time t3 when the mold temperature reached T2.

During this time, injection start time t1, temperature TI, mold temperature drop T
No mutual relation control was performed between 1 to T2 and compression forces P3 to P4, etc., and the addition of compression force, the end of cooling, the removal of compression force, etc. were performed under time control using a timer. .

Under such a molding cycle, compression is performed while the resin in the cavity 10 is cooling, so the compression effect is reduced due to cooling contraction of the resin, and the surface accuracy is approximately 1.5 to 1.0 μm.
Only molded products can be obtained.

In addition, the shape accuracy, especially the irregularity of the middle diameter of the curvature, is approximately 0.0
It has a large size of 5 to 0.1 fins, making it difficult to put it into practical use as a high-precision molded product.

Furthermore, as described in nfI, during the cooling time t2 to 1s during which the temperature of the resin in the middle cavity 1O decreases from T to T,
Since the compressive force of P, ~P, was not controlled, inappropriate pressure was applied to the resin during cooling and solidification, which frequently caused stress cracks and surface layer peeling.

As mentioned above, in the conventional molding cycle 2, the surface axis is low, the shape accuracy is highly variable, and the stability is poor.
The disadvantage was that it was rarely possible to obtain a molded product.

Furthermore, since the compression force was not controlled in accordance with the temperature, there was a drawback that defects may occur on the surface of the molded product due to excessive compression force.

[Purpose of the invention]

The present invention eliminates the drawbacks of the prior art described above and has a surface accuracy of 0.3 to 0.6 μm1 shape accuracy (mainly FjJ1 ratio cow diameter).
The purpose is to provide an injection compression molding mold for molding precision molded products such as glass lenses with a flaking of 0.0311III or less and no stress cracks or peeling of the surface layer, and a molding method thereof. Ru.

[Summary of the invention]

In order to achieve the above object, the present invention provides a conventional injection compression mold with means for detecting the temperature of the input piece, and based on the output of the temperature detection + attack, the fixed mold, the movable mold, and the input piece. controlling the temperature of the piece as a function of time according to a predetermined pattern, and based on the output of the temperature sensing means;
A temperature control means is provided to control the pressurizing force of the pressurizing cylinder,
The feature is that the following molding method is used.

(1) During the pressure holding process after the resin is filled into the mold cavity by the molding machine, compressive force is applied to the resin in the cavity to pre-shape the resin in the cavity, and at the same time, This improves the degree of adhesion between the resin in the cavity and the mold fixed and movable insert pieces (hereinafter, for the sake of brevity, both fixed and movable pieces are referred to as insert pieces), and reduces the heat between the resin in the cavity and the mold. Ensure sufficient communication.

(2) Next, the resin gold in the cavity is cooled or left for a while to promote internal assimilation. After that, the temperature of the resin is raised to a temperature higher than the softening temperature of the resin, and the surface of the resin in the cavity is heated. Rather than melting only the layers.

(3) Next, compressive force is applied again to the resin in the cavity to shape the molten surface layer, and at the same time, cooling of the fixed and movable insert pieces is started, and the cooling temperature is adjusted to match the cooling temperature of the resin. , so as to control the compressive force being applied to the resin within the cavity.

[Embodiments of the invention]

A specific embodiment of the present invention will be described below with reference to FIGS. 2 and 3. .

Fig. 2 is a cross-sectional view of an injection compression molding die showing a specific embodiment of the present invention applied to the molding of plastic lenses, and Fig. 3 is an injection compression molding die of an embodiment of the present invention. FIG. 3 is a pattern diagram showing changes in pressure and temperature over time when using the same method.

The same reference numerals as in FIG. 2 and FIG. 4 refer to the same or equivalent parts (i: hail).

11 is a heater inserted into the fixed sleeve 2 and the ringing sleeve 8 in order to heat the fixed insert piece 1 and the ringing insert piece 5; 12 is a heater for detecting the temperature of the fixed insert piece 1υ and the ringing insert piece 5; It is a temperature sensor.

Reference numeral 15 indicates a heating and cooling medium ( (not shown), and also sends a control signal to the hydraulic pressure control device 16 to control the generated hydraulic pressure.

The molding operation and molding method of the injection compression mold constructed as described above will be described in detail below with reference to the pattern diagram in FIG.

When the fixed mold 3 and the movable mold 9 attached to the injection molding machine (not shown) via the fixed mold mounting plate 4 and the movable mold mounting plate 17 are closed, from the injection molding machine, Resin (not shown) is injected into the cavity lo through the sprue 19 and runner 20.

When the resin is filled into the cavity 10, the state shown in FIG. 3, P9.
~PN, the injection molding machine moves directly to the pressure holding process and continues to apply the holding pressure shown in Figure N3 and PN1 to the resin in the cavity IO.

At the same time as the injection molding machine shifts to holding pressure, the hydraulic control device receives a signal from the injection molding machine to start holding pressure, and the pressure control device receives a signal from the injection molding machine to start holding pressure, and the pressure control device starts holding pressure from the injection molding machine. After a certain period of time as shown in FIG. 3 has passed, the resin in the cavity 10 under pressure is compressed as shown in FIG. Rikishichi takes it.

As a result, the resin in the cavity lo is shaped and at the same time, the degree of adhesion between the resin in the cavity lo and the fixed insert piece 1 and the ringing insert piece 5 is improved, and the inside of the cavity bu in the subsequent process is improved. resin and fixed insert piece 1, ringing insert piece 5
to facilitate heat transfer between the

During the time axis until tN4 when the pressure holding process of the molding machine ends, the temperature of the resin in the cavity 1θ increases from TN1 to TN2.
lower to This cooling is accomplished by heating and cooling medium passages 13
A refrigerant (not shown) is passed through the tube, or a thermovib (
(not shown) to a temperature as shown in TN2,
As a result, cooling of the resin inside the cavity IO is promoted.

Generally, the cooling temperature at this time is the softening temperature of the resin!
The temperature is kept as low as 112θ°C, and for example, in the case of acrylic resin, it is cooled to 80°C in an internal or external trench.

Next, the resin in the cavity 10 is heated at the temperature shown at T and 13 by heating the tank 11 or by heating a heating medium (not shown) and introducing it into the cooling medium passage 13. Let's go.

By this heating, only the surface layer of the resin in the gearbity lo is melted (1), and this temperature is generally set 20 to 30° C. higher than the softening temperature of the resin. For example, in the case of PMMA1
The temperature is 20-130°C.

The temperature of T83 at which heating is completed, Lv cavity fill.

The resin inside is recompressed and cooled in parallel. Compression is performed by generating hydraulic pressure by a hydraulic control device 17 controlled by a temperature controller 15, and sending this hydraulic pressure to the pressurizing cylinder 14.

During compression, since cooling is also performed using a thermopipe and refrigerant at the same time, the temperature controller 1
5 sends a control signal to the hydraulic control device 16.

This control signal causes the hydraulic control device 16 to control the pressure cylinder 1.
By controlling the hydraulic pressure sent to the resin in the cavity 10, excessive strain is added to the resin in the cavity 10 as cooling progresses.

This progress is from time tN to tN6,
The temperature decreases from TNs to TN4 and at the same time the pressure decreases to P□
It is shown in the figure as a decreasing change from PH to 6. This temperature-pressure control can be performed according to a control diagram stored in the hydraulic control device 16 in advance.

When the cooling temperature reaches NTIJ4, the hydraulic pressure of the hydraulic control device 16 is lowered from PH6 to 0, a cycle end signal is sent to the injection molding machine from the temperature controller 15, the mold is opened, and the molded product is transferred to the cavity 1o. Take out the p.

Next, the mold is closed again, the temperature is raised to TNl, and the process continues by repeating the process from the beginning.

In this embodiment, the hydraulic control device 16 and the pressurizing cylinder 14 are used to control the cavity l.

Although the resin inside the molding machine is compressed, the present invention is not limited to this, and it goes without saying that a pressurizing mechanism may be provided within the molding machine and utilized.

Next, we will discuss a concrete molding experiment example for a plastic lens made of PMMA (acrylic) resin (curvature radius 16w+-2).
6 mm, outer diameter 11520 mm, and center thickness 7 io+) will be described as an example.

When the fixed mold 3 and the movable mold 9 are closed in response to a signal to start molding, the molding machine injects and fills the lens cavity 10 with molten and plasticized PMMA resin through the sprue 19 and the runner 2o.

The filling pressure shown in Figure 3 PN1 is usually 500 to 1000.
kJi, and when the molding machine side detects this filling from the screw position and oil pressure rise, it continues to display PN1 to P in Figure 3.
Moving on to holding pressure between 500 and 1200 on H2.

The hydraulic control device [16] which receives this pressure holding start signal is shown in FIG. After a certain period of time (5 to 10 seconds) shown in , the hydraulic pressure sent to the hydraulic cylinder 14 causes the P in the lens cavity 10 to
50 to 200 as shown in Figure 3 PN3 to MMA resin.
Add a compressive force of kJi.

Through this compression, the shapes of the fixed insert piece 1 and the movable insert piece 5 are sufficiently shaped by the PMMA resin in the lens cavity 10, and the degree of adhesion between both insert pieces and the PMMA resin is improved, which facilitates subsequent heat transfer. becomes more adequate.

Next, cooling is performed from the initial mold temperature of 80 to 100°C as shown in FIG. 3 TN1 to 80 to 90°C as shown in T2.

This cooling promotes internal solidification of the 1M fat inside the lens cavity IO.

Subsequently, 110 to 1 corresponding to TN3 in FIG.
PMM inside lens cavity 10 is heated to 40°C.
A: Only the surface layer of the resin is melted.

At this time, the purpose of heating and melting only the surface layer fL9 is to minimize the amount of resin shrinkage that occurs during the next cooling and solidification. This makes it more difficult to ensure precision, shape accuracy, and surface accuracy.

Following this process, the resin within the lens cavity 1θ is recompressed and cooled. Figure 3: 50-200% shown by P
With recompression of the lens cavity l.

The surface shapes of the fixed insert piece 1 and the movable insert piece 5 are faithfully transferred to the resin surface melt layer inside, and gradually solidify by cooling.

Simultaneously with the cooling, the temperature controller 15 controls the hydraulic pressure generated by the υ hydraulic pressure control device 16 to prevent excessive compressive force from being applied to the resin surface layer inside the lens cavity IO, which is undergoing solidification.

This process is the pressure change shown in FIG.
During the reduction from 0 to 80 °C, the pressure was controlled according to a predetermined function, from 50 to 2001i of pNa to PIJ6
of 30 to 150 eagle.

When the temperature drops to 70 to 80° C. of TN4, the molded product is taken out from the cavity 10.

The PM resin lens manufactured by the above-mentioned molding method has a conventional surface precision of 1.5 to 1.0 μm (interference fringes of 5 to 1.0 μm).
3), and the variation in the radius of curvature corresponding to the shape accuracy @
It was possible to significantly improve the power consumption by 0.05 to 0.1w.

That is, the surface layer r&0.6 to 0.3 μm (interference fringes 2 to
1), and the radius of curvature variation was within 0.03 m.

In addition, by controlling the compressive force during cooling, it has become possible to obtain stable PMMA lenses that eliminate stress cracks and delamination on the surface.

Lenses molded by this method have the above-mentioned high surface precision and shape precision, so they can be put to practical use in high-precision optical systems.

As mentioned above in the plastic lens molding example, (1) the adhesion to the molding and metal parts can be improved by applying compressive force during holding pressure, and (2) the temperature inside the resin can be lowered by subsequent cooling. After solidification, recompression is performed after melting only the 9 surface layer by reheating, so the amount of resin shrinkage due to subsequent cooling can be extremely reduced. (3) At the same time as cooling, recompression force is applied. Since the temperature is controlled according to the temperature, it has the advantage of preventing excessive pressure from being applied to the resin surface layer that is solidifying. Set the accuracy to 0.
A dramatic improvement of 6 to 0.3 μm was achieved.

In addition, the variation in shape accuracy (lens radius of curvature) has been reduced to 0 compared to the conventional
．． We were able to significantly shorten the distance from 0.05~0.1 to within 0.03 m.

Furthermore, application of excessive compressive force during cooling can be avoided, making it possible to continuously obtain molded products without stress cracks or surface layer peeling.

In addition, as a result of these comprehensive effects, it has become possible to stably mold plastic lenses that can be put to practical use.

In the above, the fixed inserting piece is provided on a fixed type and the movable inserting piece is provided on a movable platen. However, the present invention is not necessarily limited to this. For example, the movable inserting piece is provided on a fixed type. It goes without saying that it may be provided in

In addition, in 3 above, the resin in the cavity described above,
Although the reheating and recompression steps that are performed immediately after the cooling step immediately after the pressure holding step are performed only once, they are not limited to this, and may be repeated two or more times. Good things are natural.

〔Effect of the invention〕

As described above, the present invention provides a means for detecting the temperature of a fixed type, a movable platen, and an input piece, and a means for detecting the temperature of a fixed type, a movable platen, and a movable platen based on the output of the temperature detection means. and temperature control means for controlling the temperature of the input piece as a function of time according to a predetermined pattern, and for controlling the pressurizing force of the pressurizing cylinder based on the output of the temperature detecting means; In the molding process used, (1) compressive force is applied to the resin in the cavity during the pressure holding process of the injection molding machine to perform pre-shaping, and at the same time, the adhesiveness with the mold is improved and the resin inside the cavity is ensure sufficient heat transfer with the resin, (2) then increase the entering piece temperature above the thermal deformation temperature of the resin to melt only the surface layer of the resin inside the cavity, and (3) further, here By applying compressive force again to the lens, the straight surface accuracy is significantly improved from 0.6 to 0.3 μm compared to the conventional method, and the variation in shape accuracy (mainly radius of curvature in the case of lenses) is reduced to 0.03 μm. This method has the advantage that it is possible to stably mold a plastic lens with a size of less than m that can be used for practical purposes.

In addition, since the compression force of the resin in the cavity is controlled based on the Venus temperature detected by the temperature sensor, there is no need to apply excessive compression force while the resin in the cavity is being cooled. It has the advantage that molded products without stress cracks or surface layer peeling can be obtained continuously.

Furthermore, as described above, according to the present invention, molded products with a straight surface accuracy of 0.3 to 0.6 μm and a variation in N degree of 0.03 μm or less and no stress cracks or surface layer peeling can be stably obtained. Is it plastic? Another advantage is that it has a great effect on the practical application of precision molded products such as molds.

[Brief explanation of the drawing]

Figure 1 shows the pressure when using conventional injection compression molding Venus.
FIG. 2 is a cross-sectional view showing a specific example of the application of the present invention to the formation of a plastic lens, and FIG. 3 is a pattern diagram showing changes in temperature over time. Pressure when using the injection compression mold of the example,
FIG. 4 is a pattern diagram showing the change in temperature over time. FIG. 4 is a cross-sectional view of a conventional injection compression mold used for molding a plastic lens. l...Fixed insert piece, 2...Fixed sleeve, 3...Fixed type, 5...Movable insert piece, 9...Movable type, 10...
Cavity, 11... Heater, 12... Temperature sensor, 13... Heating and cooling medium passage, 14... Pressurizing cylinder, 15... Temperature controller, 16... Hydraulic control device first Figure O 2 Figure 74 Figure 3 - Time

Claims (4)

[Claims] (1) A fixed type and a mover, which are arranged facing each other and have a slidable entry piece on at least one side, and the entry piece and the m-t or entry piece opposite thereto. , a cavity into which resin is injected and filled, a pressure cylinder that generates a pressure force for pressing the input piece, means for controlling the pressure force generated by the pressure cylinder, and the fixing member. and a means for heating and cooling the cavity, and means for detecting the temperature of the molding piece in the injection compression molded metal molding machine, which applies pressure to the molding piece to apply compressive force to the resin in the cavity. Based on the output of the temperature detection means, the temperature of the direct-talk fixed type, 0II411fi, and the input piece is controlled as a function of time according to a predetermined pattern, and the temperature of the It is made of injection compression molded metal and is characterized by being equipped with a temperature control middle stage that controls the pressurizing force of the pressure cylinder. (2) For either fixed type or driving piece placed opposite to each other, a piece is formed between a sliding piece provided on one side and a sliding piece or a piece placed opposite thereto. In the injection compression molding method, the resin is injected into the cavity, and then put into a pressure cylinder, and pressure is applied to the input piece to apply compressive force to the resin in the cavity. After filling the inside with resin, compressive force is applied to the resin by the pressurizing cylinder during soil excavation, and then the retaining force is removed while the soil contracting force is maintained, and the fixed plate is 2 and Enkiho are once cooled to below the softening temperature of the resin to solidify the resin, and then heated to a fixed type Fuyobi Tsukasa J1111 to cool the resin to above its softening temperature. temperature, softening its surface and reapplying a compressive force to the resin in the cavity, and then gradually reducing the compressive force as a function of decreasing the temperature of the fixed mold and the movable mold. An injection compression molding method characterized by: (3) The temperature reached when fully heating the fixed and movable molds is 20 to 20% higher than the softening temperature of the resin in the cavity.
Patent characterized by 30℃ higher temperature (4) After the fixed mold and the movable mold are once cooled to below the softening temperature of the resin and the resin is solidified, the fixed mold and the movable mold described in n11 are heated, and the resin is solidified. Claim 2 or 3, characterized in that the step of softening the optical surface by reaching a temperature equal to or higher than the softening temperature and the step of applying recompression force to the resin are performed two or more times. The injection compression molding method described.