JP4024651B2 - Resin mold and resin molding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention resin molding die to enable molding of a resin molded article having a fine three-dimensional shape and relates to a resin molding equipment.
[0002]
[Prior art]
When molding thermoplastic resin using injection molding or blow molding, etc., it is a good product with improved external appearance due to improved mold surface transfer, weld lines, flow marks, etc. Is required. Conventionally, in order to improve the surface transferability and reduce the appearance defect, generally, the object has been achieved by optimizing molding conditions such as high mold temperature or resin temperature, high injection pressure, and high-speed injection. .
[0003]
FIG. 10 is a cross-sectional view showing an example of a conventional resin molding die, wherein 1 is a mold fixing part, 2 is a mold movable part, 3 is a resin-filled space part into which the thermoplastic resin composition A is poured, 4 is It is a metal thin film provided at the bottom of the resin filling space 3.
[0004]
When resin molding is performed using this mold, the molding condition having a particularly large influence is the mold temperature, and it is preferable to increase the temperatures of both molds 1 and 2. That is, it is important to make it difficult for the heat in the resin filling space 3 to be transmitted (in the direction of the arrow) to the mold movable part 2 in the resin filling process. Has been adopted.
[0005]
[Patent Document 1]
JP-A-7-285169 [0006]
[Problems to be solved by the invention]
However, increasing the temperature of the entire mold leads to the fact that it takes a long cooling time to cool in the mold until it reaches a temperature at which the molten thermoplastic resin can be taken out as a molded product. There is a problem of reducing efficiency.
[0007]
For this reason, there is a demand for a method that can rapidly heat / cool the mold temperature. In response to these requirements, conventionally, heating and cooling pipes have been provided in the mold, depending on the molding process. A method of heating / cooling by alternately circulating a heat medium and a refrigerant body is employed (see Patent Document 1).
[0008]
However, this conventional method consumes a large amount of heat energy and does not improve production efficiency. For these reasons, there is a demand for a molding die and a molding method in which the resin temperature is unlikely to decrease in the resin filling step, and the resin temperature can be rapidly decreased in the cooling step.
[0009]
The present invention solves the above-mentioned conventional problems, makes it difficult for the resin temperature to decrease in the resin filling process in the resin molding process, and allows the resin temperature to be rapidly decreased in the cooling process, thereby improving transferability and appearance. and to provide a resin molding die and a resin molding equipment that can be improved.
[0010]
[Means for Solving the Problems]
To achieve the above object, a resin molding die and a resin molding equipment according to the present invention, the thermoplastic resin composition is heated to a temperature higher than the glass transition temperature, the thermoplastic resin composition temperature of the inner surface In a resin mold used for resin molding to obtain a resin molded product by pouring and cooling into a resin-filled space set to a temperature lower than the temperature of the reduced-pressure gas chamber via a heating element with respect to the resin-filled space are those was provided, thereby, in the heat generation control of the outgoing hot body, it is possible to control the heating temperature, it is possible to suppress the resin temperature in the resin filling process is lowered, although the reduced pressure The thermal conductivity can also be controlled by controlling the pressure of the gas chamber, and a decrease in the resin temperature can be suppressed. In addition, the resin temperature can be rapidly lowered by the contact of the cooling block in the cooling step, and the transferability and the appearance can be improved.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings. In the following description, members corresponding to those already described are denoted by the same reference numerals.
[0012]
FIG. 1 is a cross-sectional view of a resin mold for explaining an embodiment of the present invention, wherein 1 is a mold fixing part, 2 is a mold movable part, and 3 is a resin filling into which a thermoplastic resin composition A is poured. The space portion 4 is provided on the bottom surface of the resin-filled space portion 3 and is subjected to a metal thin film treatment such as Ni or Cu, and further formed with fine irregularities. A metal plate 7 is provided below the position and in which the thin film heating element 6 is incorporated, and 7 is a decompressed gas chamber provided in the mold movable part 2 below the position where the metal thin film 5 is installed.
[0013]
The thin film heating element 6 provided inside the metal plate 5 is installed to rapidly heat the temperature of the transfer surface 4a which is the surface of the metal thin film 4, and the heat of the resin in the resin filling step is mold. The decompressed gas chamber 7 is provided under the metal plate 5 in order to eliminate the sudden decrease in the resin temperature. That is, in the reduced pressure gas chamber 7, the decrease in the resin temperature is controlled by utilizing the phenomenon that the thermal conductivity decreases as the pressure is reduced.
[0014]
The gas used in the decompression gas chamber 7 is not particularly limited, but it is preferable to use air in consideration of cost. However, when contacted with air-dissolved oxygen at a high temperature for a long period of time, problems such as oxidation may occur depending on the material. Therefore, it is preferable to use an inert gas such as nitrogen in order to solve the problem.
[0015]
Furthermore, the gas density in the decompression gas chamber 7 can be managed by the gas pressure. FIG. 2 is a cross-sectional view showing an example of a pressure adjusting mechanism installed in the decompression gas chamber 7. A through hole 21 communicating with the outside air is formed in the side wall of the decompression gas chamber 7, and the piston is movably moved to the through hole 21. 22, the enlarged diameter portion 22 a of the piston 22 is disposed opposite to the elastic ring body 23 provided on the inner wall of the decompression gas chamber 7, and a spring 24 that urges the enlarged diameter portion 22 a against the elastic ring 23 is supported by the support frame. This is a structure provided in the body 25.
[0016]
The pressure of the decompression gas chamber 7 is determined by the relationship between the force P due to the decompression force applied to the piston 22 and the force Q due to the elastic force of the spring 24 applied to the piston 22, and when the force P becomes weak, the diameter-enlarged portion 22 a of the piston 22. Is in close contact with the elastic ring body 23, thereby increasing the decompression force. Further, when the force P is increased, the diameter-enlarged portion 22a of the piston 22 is separated from the elastic ring body 23, and outside air enters through the through hole 21, so that the decompression force is reduced.
[0017]
By adjusting the pressure of the decompression gas chamber 7 in this manner, the gas density decreases because the vacuum state is approached during decompression. As a result, the thermal conductivity decreases slightly. When the thermal conductivity is lowered, the temperature on the transfer surface 4a on the surface of the metal thin film 4 is difficult to decrease, and the fine shape of the mold is easily transferred to the molded product. That is, in order to improve transferability, the pressure is adjusted so that the reduced pressure gas chamber 7 is reduced in pressure to approach a vacuum. When the transferability is improved, the pressure and gas density are lowered, and when the cooling process time is shortened, the pressure is adjusted to be higher.
[0018]
Further, since heat escapes from a portion where the decompression gas chamber 7 does not exist in the resin filling space 3, the heat insulating material 8 or the heater 9 is replaced with the decompression gas chamber 7 in the resin filling space 3 as shown in FIGS. 3 and 4. It is effective to install it in a portion where no exists (in this example, the peripheral wall in the resin-filled space 3).
[0019]
In the present embodiment, there is a problem that the resin-filled space 3 slightly expands due to the decompression force of the decompression gas chamber 7, the injection pressure of injection molding, and the mold holding pressure. Therefore, as shown in FIG. It is desirable to provide the column 10 to increase the mechanical strength.
[0020]
However, since the support 10 is in contact with or close to the metal plate 5 and the heat of the resin-filled space 3 is radiated from that portion, transfer spots due to local temperature spots may occur on the transfer surface 4a of the metal thin film 4. In that case, the occurrence of transfer spots can be solved by installing the heat insulating material 11 in the corresponding contact or in the vicinity. It is also effective to form the thermal highly conductive thin film 12 with good thermal conductivity under the metal plate 5 to reduce the temperature spots.
[0021]
Furthermore, by making the gas density of the decompression gas chamber 7 variable, the thermal conductivity of the decompression gas chamber 7 can be varied. By utilizing this, the heat insulation effect of the decompression gas chamber 7 can be finely adjusted. Can do. This makes it possible to set conditions more optimally than when conditions are determined only by general parameters such as resin temperature or injection speed.
[0022]
Further, in the molding of a molded product having a thick part and a thin part, there is a problem that the thick part 13a and the thin part 13b are formed on the mold, and the transferability varies depending on the part of the molding surface. However, as shown in FIG. 6, the problem is that the decompression gas chambers 7a and 7b are provided in accordance with the parts having different thicknesses of the molded products, and the pressures of the decompression gas chambers 7a and 7b are changed. Or as shown in FIG. 7, it can solve by providing the decompression gas chamber 7c according to the site | part from which the thickness of a molded article differs, or setting not to provide a decompression gas chamber. In the example shown in FIG. 7, the decompression gas chamber 7c is installed corresponding to only the thick portion 13c.
[0023]
Further, in the cooling step after filling the resin, the transfer surface 4 is required to be rapidly cooled in order to shorten the tact time. As a method for this, as shown in FIG. The cooling block 15 may be brought into contact with each other, and the resin temperature in the resin filling space 3 may be radiated from the contact portion to the cooling block 15. Further, the cooling block 15 is provided in the decompressed gas chamber 7 so as to be movable up and down, and the heat of the cooling block 15 is brought into contact with the cooling block cooling member 16 and released to the outside before the next cooling step. Should be introduced.
[0024]
As a resin molding apparatus for moving the cooling block 15 up and down using the mold of FIG. 8, for example, in the cooling process after resin filling, the cooling block 15 is raised and brought into contact with the lower part of the metal plate 5. In addition, the cooling block up / down drive mechanism for lowering the cooling block 15 and bringing it into contact with the cooling block cooling member 16 until the next cooling step is manually operated with an operation member having a pin structure. Alternatively, it is conceivable that the cooling block vertical drive mechanism is driven and controlled by an MPU (microprocessor unit) 17 or the like.
[0025]
It is effective to use a material with good thermal conductivity as the material of the cooling block 15. In addition, a material having high thermal conductivity such as copper is used for the cooling block cooling member 16 that contacts and cools the cooling block 15, and the cooling block cooling member 16 is connected to the outside of the mold with a material having good heat conductivity. Thus, the heat of the cooling block 15 can be radiated to the outside of the mold. In particular, by making the cooling block cooling member 16 into a corrugated shape 18 outside the mold as shown in FIG. 8, it is possible to further increase the heat dissipation by widening the contact area with the outside air. it can.
[0026]
In order to set the heating time by the thin film heating element 6 and the cooling time by the cooling block 15 or the operation timing, in the resin molding apparatus shown in FIG. 9, the transfer surface 4a and members near the transfer surface 4a (in this example, the metal plate 5, The temperature detection sensor 19 is installed in the cooling block 15), the temperature detection data is output to the MPU 20, and the MPU 20 performs arithmetic processing so that the transfer surface 4a is maintained at a predetermined temperature set in advance. Is supplied to the heat generating drive section of the thin film heating element 6 and the moving drive section of the cooling block 15 to drive it, thereby providing a temperature feedback function for heating / cooling the transfer surface 4a.
[0027]
Next, specific examples of the resin molding die, the molding method, and the molding apparatus of the above embodiment will be described.
[0028]
Example 1
In the resin molding die shown in FIG. 1, a metal thin plate in which Cu plating (which may be Ni plating) is subjected to thin film metal treatment is used as the metal thin film 4, and the thin film heating element 6 is electrically connected to the energizing device. An ITO thin film was used. The thickness of the metal plate 5 was 3 to 20 mm. This thickness should be set based on the temperature rise / cooling rate or strength on the transfer surface 4a of the metal thin film 4, but is preferably about 5 to 10 mm.
[0029]
The decompression gas chamber 7 had a thickness of 1 to 10 mm and an internal pressure of 10 to 10 ⁵ Pa. The injection resin temperature is set to 170 to 300 ° C., and the glass transition temperature of the thermoplastic resin to be used is Tg, and the thin film heating element 6 is applied until the temperature of the transfer surface 4a becomes (Tg + 1 ° C.) to (Tg + 200 ° C.). Energized. The entire mold was kept at a predetermined temperature of room temperature to 150 ° C. using a temperature control mechanism (not shown).
[0030]
As shown in FIGS. 3 and 4, it is also effective to install a heat insulating material 8 or a heater 9 in the resin-filled space 3 where the decompressed gas chamber 7 does not act to suppress rapid cooling of the resin product. It was.
[0031]
Further, in setting the pressure of the decompression gas chamber 7, it is necessary to set the optimum pressure in consideration of transferability. In order to improve the transferability, the internal pressure of the decompressed gas chamber 7 was adjusted to be low, and when it was desired to shorten the cooling time, the pressure was adjusted to be high.
[0032]
(Example 2)
The resin molding die shown in FIG. 5 is basically the same as the structure and the molding method described in the first embodiment, except that the column 10 is provided in the decompression gas chamber 7, and the tip of the column 10 is the same. Ceramics such as Al ₂ O ₃ (or a resin such as polyimide) may be used as the heat insulating material 11 to be formed, and the thickness of the heat insulating material 11 is set to 0.05 mm or more. The column 10 needs to be set appropriately depending on the method and means for fixing the column 10. In this example, since a screw is used to fix the column 10, it is based on the diameter, groove pitch, length, and the like of the screw. Thus, the relationship between the height h and the width w of the support column 10 was set to be 0.5 <h / w <6.
[0033]
(Example 3)
When molding molded products having partially different thicknesses, the resin molding dies shown in FIGS. 6 and 7 were used. Basically, it is the same as the structure and the molding method described in the first embodiment, except that two decompression gas chambers 7a and 7b are provided or the decompression gas chamber 7c is partially arranged.
[0034]
In the example shown in FIG. 6, the reduced pressure gas chamber 7a of the thick portion 13a having a thickness of 0.7 mm or more is set to 10 ⁵ Pa or less, and the thin portion having a thickness of 0.7 mm or less. The decompression gas chamber 7b of 13b was set to 10 ⁴ Pa or less. Moreover, in the example shown in FIG. 7, the decompression gas chamber 7c was installed only in the thin part 13c whose thickness of a molded product is 0.7 mm or less, and the decompression gas chamber was not installed in the other part.
[0035]
(Example 4)
The resin molding die shown in FIG. 8 is basically the same as the structure and the molding method described in the first embodiment, but in this example, a cooling block 15 is provided in the decompression gas chamber 7, and in the cooling step after filling the resin. The cooling block 15 was moved and brought close to the metal plate 5 to dissipate the heat in the resin-filled space 3. Here, as the cooling block 15, a material having good thermal conductivity such as graphite or copper was used.
[0036]
(Example 5)
FIG. 9 shows the configuration of a resin molding apparatus using the resin molding die shown in FIG. 8, and a temperature detection sensor 19 is installed on the transfer surface 4a and its neighboring members. Then, heating of the transfer surface 4a by the thin film heating element 6 was repeated immediately before the resin filling step, and cooling of the transfer surface 4a by the cooling block 15 was repeated in the cooling step after resin filling.
[0037]
At that time, in order to control the heating / cooling time, as shown in FIG. 9, the temperature detection data detected by the temperature detection sensor 19 is output to the MPU 20, and the temperature information from the temperature detection sensor 19 is preset. A temperature feedback function is provided to control the operation of the thin film heating element 6 and the cooling block 15 so as to reach a predetermined temperature.
[0038]
In this example, the temperature of the transfer surface 4a is set so as to be (Tg + 1 ° C.) to (Tg + 200 ° C.) with respect to Tg of the thermoplastic resin used for molding. The time and timing were controlled so that heating by 6 was performed for 0.5 to 30 seconds and cooling by the cooling block 15 was performed for 0.5 to 60 seconds.
[0039]
【The invention's effect】
As described above, according to the resin molding die and a resin molding equipment according to the present invention, in the heat generation control of the outgoing hot body, it is possible to control the heating temperature, lowering the resin temperature in the resin filling process Since the thermal conductivity can be controlled by controlling the pressure of the decompression gas chamber, the resin temperature can be rapidly lowered in the cooling process, and transferability can be controlled. Improvement of the appearance and quality improvement of the appearance can be realized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a resin molding die for explaining an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a configuration example of a pressure adjusting mechanism installed in a decompression gas chamber in the present embodiment. FIG. 4 is a cross-sectional view showing a configuration example in which a heat insulating material is provided in the resin-filled space portion in the present embodiment. FIG. 4 is a cross-sectional view showing a configuration example in which a heater is provided in the resin-filled space portion in the present embodiment. FIG. 6 is a cross-sectional view showing a configuration example in which a support is provided in a decompression gas chamber in FIG. 6. FIG. 6 is a cross-sectional view showing a configuration example in which a plurality of decompression gas chambers are installed in the present embodiment. FIG. 8 is a cross-sectional view showing a structural example in which a cooling block is provided in the decompression gas chamber in the present embodiment. FIG. 9 is a resin molding using the resin molding die shown in FIG. Schematic configuration diagram of the device [Fig. 10] Conventional tree Sectional view showing an example of molding die EXPLANATION OF REFERENCE NUMERALS
DESCRIPTION OF SYMBOLS 1 Mold fixed part 2 Mold movable part 3 Resin filling space part 4 Metal thin film 4a Transfer surface 5 Metal plate 6 Thin film heating element 7, 7a, 7b, 7c Depressurized gas chamber 8 Heat insulating material 9 Heater 10 Strut 11 Heat insulating material 12 Heat High-conductivity thin films 13a, 13c Thick part 13b Thin part 15 Cooling block 16 Cooling block cooling member 17, 20 MPU (microprocessor unit)
19 Temperature detection sensor 21 Through hole 22 Piston 23 Elastic ring body 24 Spring

Claims (11)

The thermoplastic resin composition heated to a temperature higher than the glass transition temperature, the temperature of the inner surface to the resin filling space portion is set to a lower temperature the temperature of the thermoplastic resin composition, a resin molded article by pouring cooled In the resin molding die used for resin molding to obtain a resin molding die, a reduced pressure gas chamber is provided to the resin filling space portion through a heating element . 2. The resin molding die according to claim 1 , wherein a metal plate having the heating element therein is provided between the reduced pressure gas chamber and the resin filling space . 3. The resin molding die according to claim 1, wherein the heating element is an ITO film . 4. The resin molding die according to claim 2, wherein the metal plate has a thickness of 3 to 20 mm . The resin molding die according to any one of claims 1 to 4, wherein the decompressed gas chamber is filled with an inert gas . The resin molding die according to any one of claims 1 to 5, further comprising pressure adjusting means for adjusting a gas pressure inside the decompressed gas chamber . The resin molding die according to any one of claims 1 to 7 , wherein a column made of a metal, a heat insulating material, or a combination thereof is provided in the decompressed gas chamber . The resin molding die according to claim 7 , wherein the plurality of support columns are arranged at equal intervals or uneven intervals . The resin molding die according to any one of claims 1 to 8 , wherein a cooling block for dissipating heat of the resin-filled space is provided inside the decompressed gas chamber . In a resin molding apparatus that molds a resin molded product using a molding die,
A resin molding apparatus that performs resin molding using the resin molding die according to claim 1 as the molding die . Detection means for detecting the temperature of the resin filling space, and control means for controlling the contact time and timing between the cooling block and the resin filling space by moving the cooling block based on the temperature data obtained by the detection means The resin molding apparatus according to claim 10, comprising:

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