JP2004249640A - Cooling device of mold for high-precision plastic optical component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive cooling device of a mold enabling highly-efficient manufacture of a molded article excellent particularly in in-transfer-plane precision (deviation of a transfer plane from the mold), in regard to the cooling device of the mold for obtaining a high-precision plastic optical component. <P>SOLUTION: This cooling device has a constitution wherein a heater plate and a cooling plate are disposed sequentially on the respective outside of a cavity part and a core part in a pair composing the mold for a thermoplastic resin. The heater plate has a large number of parallel heat transfer heaters which are provided with the function of regulating a temperature distribution in the longitudinal direction of the heaters, while the cooling plate has a large number of parallel coolant passages which are disposed so that a coolant flowing through some of the coolant passages and the coolant flowing through the other coolant passages be counter currents to each other. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is directed to the use of a thermoplastic resin raw material for an overhead projector, a wind display, a front projector, a digital camera, a head-up display, a copying machine, a laser printer, and other optical components used in optical devices, particularly, a molding surface having a reduced roughness. The present invention relates to a mold cooling apparatus for manufacturing a high-precision plastics optical component such as an optical component that requires nanometer-order smoothness and a shape accuracy of several tens of microns or less.
[0002]
[Prior art]
As a method for molding a high-precision plastic optical product, there are an injection compression molding method, a high-temperature injection molding method, a press molding method, and the like, and a projection lens (see Patent Document 1) and a projection mirror (see Patent Document 2). Such a non-spherical or spherical shape having a curvature of 15 mm or more in the mold transfer surface and having an area of 100 cm ² or more in the transfer surface accuracy (deviation of the transfer surface from the mold shape). In order to achieve a thickness of 100 μm or less, it is necessary to minimize the in-plane temperature distribution of the cavity mold and the core mold during cooling (particularly near the glass transition temperature of the molding resin).
[0003]
In order to achieve an in-transfer accuracy of 100 μm or less for a molded product molded using a mold having the above specifications, it is necessary to cool over a long time while stabilizing the temperature distribution in the mold surface. In addition, a high-precision temperature control was required, such as using a plurality of high-precision temperature controllers in accordance with a cooling pattern and performing precise temperature control, or a long time was required in the molding process, and mass productivity was poor.
[0004]
[Patent Document 1]
JP-A-2002-39610
[Patent Document 2]
JP-A-2002-228815
[0005]
[Problems to be solved by the invention]
The present invention requires a high-precision plastic optical product requiring a curvature having a height difference of 15 mm or more in a mold transfer surface, a transfer area of 100 cm ² or more, and a transfer surface accuracy of 100 μm or less, and an expensive temperature controller. Provided is a high-precision plastics mold cooling device for optical parts that enables a short molding cycle without requiring a molding cycle.
[0006]
[Means for Solving the Problems]
The present inventor is a cooling device for a high-precision plastics optical component mold that solves the above problems, the gist of which is:
(1) In a mold for a thermoplastic resin comprising a pair of a cavity mold and a core mold, a heater plate and a cooling plate are sequentially arranged outside the cavity mold and the core mold, and the heater plates are arranged in parallel. It has a function of adjusting the temperature distribution in the longitudinal direction of the heater, and the cooling plate has a large number of parallel cooling liquid passages. A cooling liquid flowing through some of the cooling liquid paths and a cooling liquid flowing through the other cooling liquid paths are arranged so as to be countercurrent to each other. It is.
(2) A plurality of electric heaters and coolant passages are provided in parallel in the cavity mold and the core mold of the thermoplastic resin mold composed of a pair of a cavity mold and a core mold, Has a function of adjusting the temperature distribution in the longitudinal direction, and the coolant flowing through some of the coolant passages and the coolant flowing through the other coolant passages are countercurrent to each other. This is a cooling device for a mold for a high-precision plastics optical component, which is characterized by being arranged as follows.
(3) The apparatus for cooling a high-precision plastics optical component mold according to any one of (1) and (2), wherein the electric heater is capable of controlling at two or more locations in the longitudinal direction. It is.
(4) The cooling device for a high-precision plastics optical component mold according to any one of the above (1) to (3), wherein a flow control valve is provided in each of the cooling liquid passages.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a cooling device for a mold for a high-precision plastics optical component of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a longitudinal sectional view of one embodiment of a cooling device for a mold for an optical component made of high-precision plastics.
FIG. 2 is a longitudinal sectional view of another embodiment of a cooling device for a high-precision plastics mold for an optical component.
FIG. 3 is a plan perspective view of one embodiment of the heater plate.
FIG. 4 is a plan sectional view of one embodiment of the cooling plate.
FIG. 5 is a plan sectional view of another embodiment of the cooling plate.
FIG. 6 is a schematic view of a cavity mold.
FIG. 7 is a longitudinal sectional view of an embodiment in which an electric heater and a cooling liquid passage are provided inside a high-precision plastics mold for an optical component.
[0008]
1 and 2, reference numeral 1 denotes a cavity mold, and the cavity mold 1 has a mirror-finished aspherical shape.
Reference numeral 2 denotes a core mold, and a pair of the core mold 2 and the cavity mold 1 constitutes a mold for molding the thermoplastic resin molded body 7.
Reference numerals 3 and 4 denote peripheral frames, and the cavity mold 1 and the core mold 2 are sandwiched and set by the peripheral frames 3 and 4.
[0009]
In FIG. 1, reference numeral 5 denotes a heater plate. The heater plate 5 has a large number of parallel electric heater insertion holes 5-1 and is arranged in contact with the outside of the cavity mold 1 and the core mold 2. Have been.
Reference numeral 6 denotes a cooling plate, which has a number of parallel cooling liquid passages 6-1 (FIG. 1), 6-2 and 6-3 (FIG. 2). They are arranged in contact.
The longitudinal direction of the insertion hole for the electric heater provided on the heater plate 5 and the cooling liquid passage provided on the cooling plate 6 are arranged in parallel (FIG. 1) even if they are arranged orthogonally (FIG. 1). Any of these may be used.
In FIG. 2, a cooling liquid path 6-2 indicates a cooling liquid path in which the cooling liquid flows from the back to the front with respect to the paper surface, while a cooling liquid path 6-3 indicates the cooling liquid in which the cooling liquid flows from the front to the back with respect to the paper surface This is an example in which liquid paths are shown, and both cooling liquid paths are alternately arranged in parallel.
As described above, the combination of the two plates, the heater plate 5 and the cooling plate 6, constitutes a mold cooling device including the cavity mold 1 and the core mold 2.
[0010]
In FIG. 3, three divided electric heaters 5-2A, 5-2B and 5-2C are inserted in the longitudinal direction in the insertion hole 5-1 of the electric heater provided on the heater plate 5. Each of the electric heaters has a function of individually controlling the temperature.
It is preferable that each of the electrothermal heaters 5-2A, 5-2B, and 5-2C has a performance capable of controlling the temperature of at least about 5 cm × 5 cm (25 cm ² ).
[0011]
In FIG. 4, the cooling liquid passages 6-2A and 6-2B and the cooling liquid passages 6-3A, 6-3B and 6-3C provided in the cooling plate 6 are arranged so that the cooling liquid alternately flows. This is an example of arrangement.
In FIG. 5, the cooling liquid flows between two cooling liquid paths 6-2A and 6-2B on the right side and two cooling liquid paths 6-3A and 6-3B on the left side provided on the cooling plate 6. In this example, the cooling liquid passages 6-2C and 6-3C located at the center of the cooling plate 6 are also arranged so as to flow countercurrently.
As described above, in the present invention, since the counterflow cooling liquid passages through which the cooling liquid flows in from both end surfaces of the cooling plate 6 are arranged, as in the case of the cooling liquid passage arrangement in which the cooling liquid flows only through one end surface of the cooling plate 6. There is no possibility that the one end face is locally overcooled, and the cooling plate 6 can be uniformly cooled as a whole.
[0012]
A flow control valve 6-4 is provided at the inlet of each cooling liquid passage, and the flow rate of the cooling liquid is controlled by adjusting the opening degree of each valve 6-4. It has a function to control the temperature distribution of the mold inner wall within 4 ° C. by adjusting the temperature of each electric heater.
The heater plate 5 and the cooling plate 6 are made of a material having a thermal conductivity λ of 50 W / m · k or more, and generally, an aluminum alloy is preferably used, and more preferably, a copper alloy is more preferably used.
[0013]
6, a typical shape of the cavity mold 1, that has a 100 cm ² or more areas in a non-spherical shape that the height difference H ₁ of the mold transfer plane had a curvature of more than 15 mm, and the mold having a minimum thickness H ₂ is 30mm aspherical from the bottom surface of the cavity mold 1, a cooling device of the present invention can be suitably used.
[0014]
FIG. 7 shows an example in which a plurality of holes 5-1 for inserting an electric heater and cooling fluid passages 6-2, 6-3 are provided alternately and parallel directly inside the cavity mold 1 and the core mold 2. .
In the longitudinal direction inside the electric heater insertion hole 5-1, three electric heaters 5-2A, 5-2B, and 5-2C divided in the same manner as the structure shown in FIG. 3 are inserted. Each of the electric heaters has a function of individually adjusting the temperature.
The cooling liquid passages 6-2 and 6-3 are arranged so that the cooling liquid flows in countercurrent to each other, and each of them is provided with a flow control valve.
In FIG. 7, when directly providing the electric heater insertion hole and the coolant passage inside the cavity mold 1 and the core mold 2, even if the mold is processed, the required strength of the mold is secured. It can be employed when the transfer surface accuracy of the mold does not deteriorate due to the influence of this processing operation.
In addition, the distances in the thickness direction from the transfer surface of the cavity mold 1 and the surface of the thermoplastic resin molded body of the core mold 2 are constant at the positions where the electric heater insertion hole and the cooling liquid passage are provided inside the mold. It is preferable to arrange them in such a manner.
[0015]
【Example】
(Example 1)
An amorphous polyolefin having a glass transition temperature of 140 ° C. (DSC method) (Zeonor: manufactured by Nippon Zeon Co., Ltd.) dried in a vacuum at 100 ° C. for 48 hours is converted into an aspherical surface having the following formula (1). a vertical (optical axis direction): 160 mm, transverse (perpendicular to the optical axis): 160 mm, thickness: a size of 8 mm, it is _{H 2} in FIG. 6 30mm, _{H 1} is the resin molding die 30mm In the thickness direction, the mixture was heated at 240 ° C. for 50 minutes at a pressing pressure of 0.7 MPa while being melted by heating to form a shape.
Thereafter, from 240 ° C. to 100 ° C., a molded product 7 was obtained by gradually cooling over 40 minutes while applying a pressure of 0.5 MPa in the thickness direction so as to follow the shrinkage of the resin.
[0016]
The heater plate 5 used to obtain the molded body 7 has the structure shown in FIG. 3 and is made of 7075-based aluminum alloy. It has a structure with a heater.
In the above-described slow cooling step, the heater plate 5 on the side of the cavity mold 1 sets the temperature of the electric heater 5-2B of FIG. 3 to 240 ° C. initially, and sets the temperature of the electric heaters 5-2A and 5-2C to this. Was also set 5 ° C. lower.
On the other hand, in the heater plate 5 on the core mold 2 side, the temperature of the electric heaters 5-2A and 5-2C in FIG. 3 was initially set at 240 ° C., and the temperature of the electric heater 5-2B was set at 10 ° C. lower than this.
[0017]
Further, the cooling plate 6 on the side of the cavity mold 1 closes the cooling liquid passage 6-3B with the flow rate adjusting valve 6-4 in the mode shown in FIG. 4, and controls the amount of cooling water flowing through the cooling liquid passages 6-2A and 6-2B. The total amount of water was made equal to 15 L / min, and similarly, the amount of cooling water flowing through the cooling liquid passages 6-3A and 6-3C was made equal to adjust the total amount of water to 15 L / min with the flow control bubble 6-4. .
On the other hand, in the cooling plate 6 on the core mold 2 side, the cooling fluid passages 6-3A and 6-3C are closed by the flow control valve 6-4 in the manner shown in FIG. 4, and the cooling fluid passages 6-2A and 6-2B flow. The cooling water amount was made equal to adjust the total water amount to 15 L / min, and the cooling water amount flowing through the cooling liquid passage 6-3B to 15 L / min with the flow control bubble 6-4.
[0018]
As described above, the temperature of each electric heater of the heater plate 5 is controlled while flowing a fixed amount of cooling water through the cooling plate 6, and the temperature of the mold minimum thickness (H ₂ ) portion of the cavity mold 1 and the mold are controlled. While maintaining the temperature difference at the maximum thickness (H ₁ + H ₂ ) portion within 4 ° C., the resin temperature is lowered from 240 ° C. to 100 ° C. to form the molded body 7, and then the molded body 7 is heated at 100 ° C. Removed from the mold.
The maximum deviation of the transfer surface of the molded body 7 thus obtained from the reference shape was 40 μm.
[0019]
^{Z (h) = ch 2 /} (1 + √ (1- (1 + k) c 2 h 2)) + Ah 4 + Bh 6 + Ch 8 + Dh 10 ...... (1)
(C = 1 / r, c: curve, r: radius, k: cone ratio, A, B, C, and D are coefficients)
r = -160
k = -8.0
A = ^7.0-9
B = ^{-9.0 -14}
C = ^6.5-19
D = ^{-2.0 -24}
[0020]
(Comparative Example 1)
In Example 1, in the step of gradually cooling the molten resin at 240 ° C. in the mold to a resin temperature of 100 ° C. to obtain a molded body 7, the cooling plates 6 on the cavity mold 1 side and the core side 2 are replaced with the cooling plate 6 in FIG. And the total amount of cooling water flowing through the cooling liquid paths 6-2A and 6-2B is equalized to 15 L / min, and the amount of cooling water flowing through the cooling liquid paths 6-3A, 6-3B and 6-3C is equalized. The total cooling water amount was adjusted to 15 L / min to a constant flow rate by the flow control valve 6-4.
On the other hand, while controlling all the electric heaters inserted into the heater plate 5 on the cavity mold 1 side and the core side 2 at the same temperature, a pressure of 0.5 MPa is applied so as to follow the shrinkage of the resin from 240 ° C. to 100 ° C. The molded body 7 was gradually cooled in the added state over 40 minutes to form the molded body 7, and then the molded body 7 was taken out of the mold at 100 ° C.
The temperature difference between the mold minimum thickness (H ₂ ) portion and the mold maximum thickness (H ₁ + H ₂ ) portion in the cavity mold 1 at the time when the resin temperature reaches 100 ° C. after gradual cooling is 10 ° C. The maximum deviation of the transfer surface of the molded body 7 thus obtained from the reference shape was 60 μm.
[0021]
(Comparative Example 2)
In Example 1, in the step of gradually cooling the molten resin at 240 ° C. in the mold to a resin temperature of 100 ° C. to obtain a molded body 7, the cooling plates 6 on the cavity mold 1 side and the core side 2 are replaced with the cooling plate 6 in FIG. And the total amount of cooling water flowing through the cooling liquid paths 6-2A and 6-2B is equalized to 15 L / min, and the amount of cooling water flowing through the cooling liquid paths 6-3A, 6-3B and 6-3C is equalized. The total cooling water amount was adjusted to 15 L / min to a constant flow rate by the flow control valve 6-4.
On the other hand, while controlling all the electric heaters inserted into the heater plate 5 on the cavity mold 1 side and the core side 2 at the same temperature, a pressure of 0.5 MPa is applied so as to follow the shrinkage of the resin from 240 ° C. to 100 ° C. With added, 15 minutes from 240 ° C to 160 ° C, 30 minutes at 160 ° C, 10 minutes from 160 ° C to 140 ° C, 30 minutes at 140 ° C, 30 minutes from 140 ° C to 100 ° C, and 30 minutes at 100 ° C By gradually cooling over a total of 145 minutes, the temperature difference between the mold minimum thickness (H ₂ ) portion and the mold maximum thickness (H ₁ + H ₂ ) portion in the cavity mold 1 is maintained within 4 ° C. After forming the molded body 7 by pressing, the molded body 7 was taken out of the mold at 100 ° C. The maximum deviation of the transfer surface of the molded body 7 thus obtained from the reference shape was 40 μm.
[0022]
【The invention's effect】
The mold cooling device of the present invention does not require expensive initial equipment investment and has a relatively short molding cycle, and thus has excellent productivity.
Further, since the maximum deviation of the transfer surface of the obtained molded body 7 from the reference shape is small, it can be suitably used as a mold cooling device for plastics optical components requiring high accuracy.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of one embodiment of a cooling device for a mold for a high-precision plastics optical component.
FIG. 2 is a longitudinal sectional view of another embodiment of a cooling device for a mold for an optical component made of high-precision plastics.
FIG. 3 is a plan perspective view of one embodiment of a heater plate.
FIG. 4 is a plan sectional view of one embodiment of a cooling plate.
FIG. 5 is a plan sectional view of another embodiment of the cooling plate.
FIG. 6 is a schematic view of a cavity mold.
FIG. 7 is a longitudinal sectional view of one embodiment in which an electric heater and a cooling liquid passage are provided inside a high-precision plastics mold for an optical component.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cavity type | mold 2 ... Core type | mold 3, 4 ... Peripheral frame 5 ... Heater plate 5-1 ... Hole 5-2A, 5-2B, 5-2C for electric heater insertion ... Electric heater 6 ... Cooling plate 6-1. 6-2, 6-3 ... Cooling fluid path 6-2A, 6-2B, 6-3A, 6-3B, 6-3C ... Cooling fluid path 6-4 ... Flow control valve 7 ... Thermoplastic resin molded body

Claims (4)

A heater plate and a cooling plate are sequentially arranged on the outside of the cavity mold and the core mold of the thermoplastic resin mold composed of a pair of a cavity mold and a core mold. It has a heater and has a function of adjusting the temperature distribution in the longitudinal direction of the heater, and the cooling plate has a large number of parallel cooling liquid passages. A cooling device for a high-precision plastics optical component mold, wherein the cooling liquid flowing through the cooling liquid path and the cooling liquid flowing through the other cooling liquid paths are arranged to be countercurrent to each other. A plurality of electric heaters and cooling fluid passages are provided in parallel in the cavity mold and the core mold of the thermoplastic resin mold composed of a pair of a cavity mold and a core mold, and the electric heater has a longitudinal axis. It has a function of adjusting the temperature distribution in the direction, and so that the coolant flowing through some of the coolant passages and the coolant flowing through the other coolant passages are countercurrent to each other. A cooling device for a mold for optical components made of high-precision plastics, which is arranged. The cooling device for a high-precision plastics optical component mold according to any one of claims 1 to 2, wherein the electric heater can control two or more locations in the longitudinal direction. 4. The cooling device for a high-precision plastics optical component mold according to claim 1, wherein a flow rate adjusting valve is provided in each of the cooling liquid passages.

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