JP2006256078A - Press molding apparatus, press molding method using the apparatus, and resin molding formed by the apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a press molding apparatus which can form a plurality of moldings in a desired shape by one molding process without causing enlargement, a press molding method using the apparatus, and a resin molding formed by the apparatus. <P>SOLUTION: The press molding apparatus 1 comprises a press mold 2 which has a pair of molds 3 and 4 set opposite to each other and openably/closably and forms opposite spaces with a resin material R supplied between them, a temperature control means 7 heating/cooling the resin material R, and press means 5 and 6 pressing the heated resin material R through the press mold 2 in its opening/closing direction. At least one middle mold 8 is arranged between the molds 3 and 4. The middle mold 8 has a transfer surface 11 on at least one surface opposite to the molds 3 and 4. The transfer surface 11 constitutes part of the opposite spaces, and at least two opposite spaces are formed in series to the opening/closing direction of the press mold 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a press molding apparatus, a molding method using the same, and a resin molded product formed by the press molding apparatus, and more specifically, a press molding apparatus suitable for molding a large and thin optical molded body, The present invention relates to a molding method using the same and a resin molded product formed by the press molding apparatus.

  Conventionally, an injection molding method using a transparent thermoplastic resin such as polycarbonate or acrylic resin has been adopted for molding optical lenses such as optical lenses and mirrors for cameras and printers or compact discs. In recent years, with the increase in size, thickness, and performance of optical devices in which these are used, the optical molded articles used are large and thin, and are excellent in optical properties such as low birefringence. Is required. In the conventional injection molding method, it is difficult to mold such an optical molded body. Instead, the optical molded body is molded by a special molding method such as a press molding method or an injection compression molding method. It has been known.

  In the press molding method, since the melting temperature of the resin can be set lower than in the case of the injection molding method, thermal deterioration of the resin material is prevented, and an optical molded body excellent in transparency can be obtained. In the press molding method, the resin material does not flow and the birefringence can be reduced. Since the pressure applied to the resin material is lower than that of the injection molding method, the residual stress is reduced and deformation with time is unlikely to occur. Furthermore, it is possible to obtain a molded body that is less susceptible to cracking due to oils and fats or organic solvents. Since the thermoplastic resin that has been heated and melted again is pressed and molded, stress can be relieved and an optical molded article excellent in low birefringence can be obtained.

  However, in the press molding method, since it is necessary to raise and lower the temperature of the mold in a single molding process, there is a problem that the molding process time is longer and the productivity of the molded body is low compared to injection molding. is there.

In order to solve this problem, press molding apparatuses that can obtain a plurality of molded bodies in a single molding process are known (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3). These have a plurality of molds. Each mold is composed of an upper mold and a lower mold having a transfer surface for molding the optical surface of the optical element, which are openable and closable, and are arranged in parallel to the open / close direction. Each mold is supplied with a resin material between the upper mold and the lower mold. Each resin material is heated by a heater through each mold and is set to a predetermined temperature, and then a predetermined pressure along the opening and closing direction of the mold is applied by the pressurizing means corresponding to each upper mold of each mold. Is granted. The shape of the transfer surface of the upper mold and the lower mold is transferred to the resin material subjected to this pressure, and an optical molded body having a predetermined shape is molded. Thereafter, the optical molded body and the mold are cooled to a predetermined temperature. As a result, a plurality of optical molded bodies can be simultaneously molded in a single molding step.
Japanese Patent Publication No.05-32333 JP 09-239757 A JP 09-267404 A

  However, since the above-described press molding apparatus has a plurality of molds arranged in parallel to the pressing direction, when each of the plurality of molds is heated in the molding process, the temperature of each mold is different. Will occur. Then, it becomes impossible to set each resin material supplied to each mold to a desired temperature. In the case of the press molding method, this obstructs the molding of the obtained optical molded body into a desired shape, and has a problem of greatly affecting the optical performance of the optical molded body. In addition, since it is necessary to simultaneously apply a desired pressure to each mold, there is a problem that the pressurizing means is increased in size, resulting in an increase in the size of the apparatus and an increase in cost.

  The present invention has been made in view of the above circumstances, and uses a press molding apparatus that can form a plurality of molded products into a desired shape in a single molding step without causing an increase in size. An object of the present invention is to provide a press molding method and a resin molded product formed by the press molding apparatus.

  The present applicant has found that the above-described problems are caused by the fact that a plurality of molds are arranged in parallel to the pressurizing direction of each mold. For this reason, the present invention basically includes a plurality of molds arranged in series with respect to the pressurizing direction of each mold.

  That is, in order to solve the above-described problem, the press molding apparatus according to claim 1 has a pair of opposed molds provided so as to be openable and closable, and a resin material between the opposed molds. A press mold that forms an opposed space to which the resin material is supplied, temperature control means for heating and cooling the resin material to a predetermined temperature, and the resin material that has reached the predetermined temperature via the press mold A press molding apparatus comprising a pressurizing means for applying pressure along the opening and closing direction of the press mold, wherein at least one middle mold is disposed between the opposing molds, The middle mold has a transfer surface on at least one surface facing both the opposed molds, and the transfer surface constitutes a part of the opposed space, and the opposed space opens and closes the press mold. At least two or more are formed so as to be in series with the direction And wherein the door.

  A press molding apparatus according to a second aspect is the press molding apparatus according to the first aspect, wherein a plurality of the intermediate molds are arranged in series with respect to an opening / closing direction of the press mold between the opposing molds. A mold is arranged.

  A press molding apparatus according to a third aspect is the press molding apparatus according to the first or second aspect, wherein the intermediate mold has the transfer surface on both surfaces.

  The press molding apparatus according to claim 4 is the press molding apparatus according to claim 3, wherein the intermediate mold includes a transfer surface molding portion having the transfer surface on one side as a constituent member. To do.

  The press molding apparatus according to claim 5 is the press molding apparatus according to claim 4, wherein the middle mold includes a middle mold body having the temperature control means, and the middle mold body attached to the middle mold body. It is characterized by comprising a transfer surface molding part.

  A press molding apparatus according to a sixth aspect is the press molding apparatus according to the first aspect, wherein a high frequency dielectric heating method is adopted as the temperature control means.

  The press molding apparatus according to claim 7 is the press molding apparatus according to claim 6, wherein the temperature control means includes an electrode provided in each of the opposed molds, and an electrical connection to the electrodes. And a high frequency generator connected to the terminal.

  The press molding apparatus according to an eighth aspect is the press molding apparatus according to the first aspect, wherein the resin material is a thermoplastic resin sheet.

  The press molding apparatus according to claim 9 is the press molding apparatus according to claim 1, further comprising a vacuum forming means for placing a space between the middle mold and the resin material in a vacuum atmosphere. Features.

  The press molding apparatus according to claim 10 is the press molding apparatus according to claim 1, wherein the intermediate mold is a transfer having an intermediate mold main body and the transfer surface attached to the intermediate mold main body on one side. The transfer surface molding portion is provided with a gas hole that is opened to the transfer surface, and gas is supplied from the middle mold main body portion to the gas hole, and the resin material Is released from the transfer surface molding portion by the gas injected from the gas hole.

  The press molding method according to an eleventh aspect is characterized by being performed using the press molding apparatus according to any one of the first to tenth aspects.

  A resin molded article according to a twelfth aspect is characterized by being formed using the press molding apparatus according to any one of the first to tenth aspects.

  According to the first to third aspects of the present invention, since the opposing space is arranged in series with respect to the pressing direction of the mold, the pressing means moves the pair of opposing molds in the opening / closing direction. Therefore, it is possible to reduce the size as compared with the case where a plurality of molds arranged in parallel to the pressing direction are pressed simultaneously. In addition, the difference between the temperature of each resin material and the desired temperature can be reduced as compared to simultaneously raising and lowering the temperatures of a plurality of molds arranged in parallel.

  According to the invention of claim 4 and claim 5, since the intermediate mold is formed using the transfer surface forming portion having the transfer surface on one side, the intermediate mold having the transfer surface on both surfaces is formed. It can be formed easily.

  According to the invention described in claims 6 and 7, the plurality of resin materials can be set to the same temperature without causing an increase in size.

  According to the eighth aspect of the present invention, even if a plurality of resin materials are processed at the same time, there is little increase in thickness along the opening and closing direction of the mold, so that each resin material can be set to the same temperature.

  According to the invention described in claim 9, since it is possible to prevent the resin material from being processed while air remains inside the mold, the processing accuracy of the resin molded product can be increased.

  According to invention of Claim 10, the resin molded product after shaping | molding can be released easily.

  According to the eleventh aspect of the present invention, it is possible to obtain a plurality of resin molded products formed in a desired shape in a single molding step without causing an increase in size.

  According to invention of Claim 12, it forms in the desired shape, without causing the increase in shaping | molding cost. For example, when the resin molded product is an optical molded body, it has high performance, for example, is large and thin, and is excellent in optical characteristics such as low birefringence.

  Embodiments of a press molding apparatus according to the present invention, a press molding method using the same, and a resin molded product formed by the press molding apparatus will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing a press molding apparatus 1 according to the present invention.

  In Example 1, the press molding apparatus 1 is used to manufacture the Fresnel lens F (see FIG. 2D) using the acrylic resin sheet R as the resin material.

  The press molding apparatus 1 includes a press die 2. The press die 2 has an upper die 3 and a lower die 4. The upper mold 3 and the lower mold 4 are arranged parallel to each other and facing each other in the vertical direction. The upper die 3 is provided on the press head 5, and the lower die 4 is provided on the press stage 6. The press head 5 and the press stage 6 face each other in parallel, and the press head 5 is provided to be movable in the vertical direction while maintaining the facing and parallel relation. The press head 5 also functions as a pressurizing unit that applies pressure toward the press stage 6 along this moving direction.

  Each of the upper mold 3 and the lower mold 4 is provided with a heater 7. The heater 7 is connected to a control device (not shown) and raises and lowers the temperatures of both molds 3 and 4.

  In general, the materials of both molds 3 and 4 have good machinability and grindability, excellent wear resistance, excellent mirror finish, sufficient strength and toughness , Mechanical properties and processing characteristics such as having high corrosion resistance, good crimping workability, good heat treatment characteristics, high thermal conductivity and low thermal expansion coefficient, good weld repairability Etc. are required. For this reason, both molds 3 and 4 are formed of steel for machine structural use, alloy tool steel, stainless steel or the like. In particular, if cooling performance is important, copper alloy or aluminum alloy with high thermal conductivity may be used, but stainless steel should be used from the viewpoint of strength, corrosion resistance, wear resistance, mirror finish, etc. Is desirable.

  A middle mold 8 can be arranged between the molds 3 and 4. The middle mold 8 has a middle mold body 9 and two transfer surface molding sections 10. The middle mold main body 9 has a plate shape as a whole, and both planes thereof face the molds 3 and 4, respectively. A heater (not shown) similar to the heater 7 is provided inside the middle mold main body 9, and this heater is connected to a control device (not shown) like the heater 7. Further, a gas passage (not shown) is provided inside the middle-sized main body 9, and this gas passage communicates with a gas supply device (not shown).

  Both transfer surface molding portions 10 are substantially plate-shaped as a whole, and are attached to both flat surfaces of the medium-sized main body portion 9. Both transfer surface molding portions 10 have a transfer surface 11 on the surface opposite to the mounting surface to the middle mold main body portion 9. In the first embodiment, the transfer surface 11 has a shape obtained by inverting the Fresnel lens F. Both transfer surface molding portions 10 are provided with a plurality of gas holes (not shown). Each gas hole has one end communicating with a gas passage (not shown) of the medium-sized main body 9 and the other end opened to the transfer surface 11.

  The transfer surface molding unit 10 is formed as follows. A steel blank is cut into a predetermined shape by cutting with a cutting tool, and then the processed member is subjected to heat treatment. Further, the electroless nickel plating is applied to the processed surface, the heat treatment is performed to increase the hardness, and the processed surface is cut with a diamond bit to thereby provide a transfer surface molding portion having a transfer surface 11 having a mirror surface of a desired shape. 10 is formed. The two transfer surface molding portions 10 are set to have a smaller heat capacity than the two dies 3 and 4 of the press die 2.

  An acrylic resin sheet R can be disposed between the transfer surface 11 of the transfer surface molding portions 10 and the molds 3 and 4, respectively. The acrylic resin sheet R is formed to a thickness of 1 mm in the first embodiment. Examples of the resin material used for the production of such a resin molded body include alicyclic structure-containing resins, acrylic resins, polycarbonate resins, and the like, but are not limited thereto, and the transparency of the molded body. In addition, it can be freely selected in consideration of heat resistance, low water absorption, low birefringence and the like. In addition, fine particles such as inorganic and organic fillers and beads can be blended in the resin material and used. The acrylic resin sheet R and the middle mold 8 can be arranged between the molds 3 and 4 by a conveying device (not shown).

  The press die 2, the press head 5, and the press stage 6 are disposed inside a vacuum chamber (not shown). The vacuum chamber has an opening that can be opened and closed, and the acrylic resin sheet R and the middle mold 8 can be disposed between the molds 3 and 4 from the opening.

  Next, the process of molding the Fresnel lens F, which is a resin molded product, using the press molding apparatus 1 according to the present invention will be described with reference to FIG. FIG. 2 is a schematic diagram illustrating a single molding process by the press molding apparatus 1 as (a) to (d).

  The upper mold 3 and the lower mold 4 of the press mold 2 are heated to a predetermined temperature by the heater 7 (see FIG. 2A). This predetermined temperature is equal to or lower than the glass transition temperature Tg of the acrylic resin sheet R. At this time, the heating rate is not particularly limited, but the higher the temperature raising rate, the shorter the time required for one molding step and the higher the productivity. However, if the temperature rising rate is increased, the load on the press molding apparatus 1 is also increased.

After the middle mold 8 and both acrylic resin sheets R are supplied to a predetermined position between the upper mold 3 and the lower mold 4 by a conveying device (not shown) (see FIG. 2B), the illustration is omitted. The vacuum chamber is closed, and the vacuum chamber is evacuated. The vacuum atmosphere here means an atmosphere having a degree of vacuum of 1.0 × 10 ⁻¹ Pa or less, preferably 1.0 × 10 ⁻³ Pa or less.

  The middle mold 8 is heated to a predetermined temperature by a heater (not shown) provided in the middle mold body 9. This predetermined temperature is equal to or higher than the glass transition temperature Tg of the acrylic resin sheet R.

  After setting the middle mold 8 to a predetermined temperature Tg or higher, the press head 5 is operated to move the upper mold 3 of the press mold 2 downward. Due to the downward movement of the upper mold 3, the two acrylic resin sheets R are sandwiched between the upper mold 3 and the middle mold 8, or between the lower mold 4 and the middle mold 8. Thereafter, the upper mold 3 is further moved downward, and pressure along the vertical direction is applied to both acrylic resin sheets R. By this pressurization, the shape of the transfer surface 11 is transferred to both acrylic resin sheets R, and both acrylic resin sheets R have the shape of the Fresnel lens F (see FIG. 2C). For this reason, the space sandwiched between the upper mold 3 and the transfer surface 11 and the space sandwiched between the lower mold 4 and the transfer surface 11 function as opposing spaces. This applied pressure is usually about several Pa to several tens of MPa. The holding time in the pressurized state is usually about 1 second to 5 minutes, but can be appropriately selected in consideration of factors such as the size, shape and molding accuracy of the molded product.

  After this pressurizing step, the heater of the medium-sized main body 9 is stopped. Since both the transfer surface molding portions 10 of the middle mold 8 have a smaller heat capacity than both the dies 3 and 4 of the press die 2, the heat of both the transfer surface molding portions 10 is transferred to the both dies 3 and 4 Since the transmission speed is fast, both transfer surface molding parts 10 cool in a short time. For this reason, both the molded acrylic resin sheets R are cooled to the glass transition temperature Tg or less in a short time.

  After the glass transition temperature Tg or lower, gas is injected from each gas hole (not shown) of both transfer surface molding portions 10 of the middle mold 8 while operating the press head 5 to raise the upper mold 3. Let Thereby, both the molded acrylic resin sheets R are released from the middle mold 8 and two Fresnel lenses F made of the acrylic resin sheet R can be obtained (see FIG. 2D).

  When the Applicant actually molded the Fresnel lens as described above using the press molding apparatus having the above-described configuration, each of the obtained Fresnel lenses included both the transfer surface and the opposing space. The shapes of the molds 3 and 4 and the middle mold 8 were faithfully transferred.

According to this press molding apparatus 1, the following effects can be obtained.
(1) Since both acrylic resin sheets R, which are resin materials, are supplied to opposing spaces arranged in series with respect to the pressurizing direction to the press mold 2, two sheets having a desired shape can be formed in a single molding process. The Fresnel lens F can be obtained simultaneously. For this reason, two Fresnel lenses F excellent in optical characteristics can be obtained with high production efficiency.
(2) Since both opposing spaces are arranged in series with respect to the pressurizing direction, the press head 5 and the press stage 6 as pressurizing means can apply pressure to the pair of dies 3 and 4. What is necessary is just to be able to reduce in size compared with the case where the some metal mold | die is arrange | positioned in parallel with respect to the pressurization direction. For this reason, the press molding apparatus 1 can be reduced in size, and the manufacturing cost of the press molding apparatus 1 can be reduced.
(3) Since the upper mold 3, the lower mold 4 and the middle mold 8 constituting both opposing spaces are arranged in series, each opposed to a plurality of molds arranged in parallel. The temperature of the resin material supplied to the space can be set to a predetermined temperature with high accuracy.
(4) Since the middle mold 8 has the transfer surfaces 11 on both sides, press molding can be performed more efficiently.
(5) Since the middle mold 8 has the transfer surface 11 on both sides by the configuration in which the two transfer surface molding parts 10 having the transfer surface 11 on one side are attached to the middle mold main body 9, both sides are cut. Compared with manufacturing the member which has the transfer surface 11 on both surfaces, it can manufacture at low cost.
(6) Since the heater is provided in the middle mold body 9 of the middle mold 8, the temperature of the resin material (acrylic resin sheet R) supplied into the cavity can be controlled with high responsiveness.
(7) Since only the two transfer surface molding portions 10 are press-molded at the glass transition temperature Tg or higher, the time required for heating and cooling the resin material is shorter than when the entire mold is heated and press-molded. Thus, the time required for one molding process can be greatly shortened. Furthermore, temperature control can be performed with high accuracy, and overheating due to overshoot or hunting can be prevented. This not only means that the molding process is easy to control, but also means that a molded product with higher accuracy than conventional press molding can be obtained.
(8) Since the resin material is the thermoplastic resin sheet R, even if a large number of resin materials are arranged in series with respect to the opening / closing direction of the press mold 2, the increase in thickness along the opening / closing direction of the mold is small. For this reason, the influence by the difference in the space | interval with the intermediate | middle type main-body part 9 in each part of each thermoplastic resin sheet R is lose | eliminated, and each thermoplastic resin sheet R is warmed uniformly, without producing temperature distribution inside.
(9) Since press molding is performed in a vacuum chamber in a vacuum atmosphere, air resistance can be eliminated, and even when a deep optical surface shape or a complicated optical surface shape is press molded, resin is used. The material can be imitated on the transfer surface 11 in a short time. For this reason, time required for highly accurate transfer and a single molding process can be shortened. When an optical element having a fine structure such as a diffraction ring zone on the optical surface is formed by press molding in an air atmosphere, a minute air pocket is likely to be formed especially in the fine structure, and the transferability of hot press molding is deteriorated. There is. For this reason, the fact that the space between the transfer surface 11 and each thermoplastic resin sheet R is in a vacuum atmosphere is more effective when high-precision molding is performed.
(10) Since gas is injected from the gas hole of the transfer surface 11 when the resin molded product (Fresnel lens F) is released, the resin molded product is easily released, and deformation that occurs when the resin molded product is released. Can be prevented. Note that one gas hole may be provided on the transfer surface 11, but it is desirable to provide a plurality of circles, slits, or the like. The gas to be injected is generally compressed air, but is not limited thereto, and a known gas can be used.

  In addition, although the heater was provided in the medium-sized main-body part 9 as a temperature control means, if the resin material can be heated and cooled via the medium-sized main-body part 9, for example, temperature-adjusted water and Fluids such as oil can be used, and electromagnetic waves such as infrared rays can be used, and the present invention is not limited to the first embodiment described above.

  In addition, a vacuum chamber has been employed to create a vacuum atmosphere, but it is sufficient that the space between the transfer surface 11 and the thermoplastic resin sheet R can be in a vacuum atmosphere. It is not limited.

  FIG. 3 is a cross-sectional view schematically showing a press forming apparatus 20 as another example according to the present invention.

  In Example 2, the press molding apparatus 20 is used to manufacture a lenticular lens L (see FIG. 4D) using a polycarbonate resin R ′ as a resin material.

  The press molding apparatus 20 includes a press die 21. The press die 21 has an upper die 22 and a lower die 23. The upper mold 22 and the lower mold 23 are arranged in parallel with each other and facing each other in the vertical direction. The upper die 22 is provided on the press head 24, and the lower die 23 is provided on the press stage 25. The press head 24 and the press stage 25 face each other in parallel, and the press head 24 is provided so as to be movable in the vertical direction while maintaining this facing and parallel relationship. The press head 24 also functions as a pressurizing unit that applies pressure toward the press stage 25 along the moving direction.

  The upper mold 22 and the lower mold 23 are provided with temperature control circuits (not shown). Temperature-controlled water is circulated in the temperature control circuit.

  In addition, both molds 22 and 23 are provided with an insulating plate 26 and an electrode plate 27, respectively. Each insulating plate 26 is attached to the molds 22 and 23 so as to cover the molds 22 and 23. Each electrode plate 27 is attached to each insulating plate 26, and is electrically insulated from the molds 22 and 23 by each insulating plate 26.

  A high frequency generator 28 is connected to both electrode plates 27. The high frequency generator 28 can apply a high frequency voltage of 1 MHz or more between the electrode plates 27.

  Between the two molds 22 and 23, four middle molds 29 can be arranged. Each middle mold 29 has a substantially plate shape as a whole and has a transfer surface 30 on one side. In the second embodiment, each transfer surface 30 has a shape obtained by inverting the lenticular lens L.

  A polycarbonate resin sheet R ′ can be disposed at a position facing the transfer surface 30 of each middle mold 29. The polycarbonate resin sheet R ′ is formed to a thickness of 0.5 mm in the second embodiment. As the polycarbonate resin sheet R ′, a sheet in which the dielectric constant ε and the dielectric loss tangent tan δ which are electrical characteristics satisfy the relationship of 0.01 <ε × tan δ is employed. The polycarbonate resin sheet R ′ and the middle mold 29 can be placed between the molds 22 and 23 by a transport device (not shown).

  Next, a process of molding the lenticular lens L which is a resin molded product using the press molding apparatus 20 according to the present invention will be described with reference to FIG. FIG. 4 is a schematic diagram showing a single molding process by the press molding apparatus 20 as (a) to (d).

  In the opened press die 21 (see FIG. 4A), each middle die 29 and each polycarbonate resin sheet R ′ are placed in a predetermined position between both electrode plates 27 by a conveying device (not shown). (Refer to FIG. 4B). Thereafter, the press head 24 is operated to lower the upper mold 22 and clamp the mold.

  The upper mold 22 is further lowered, a predetermined pressure is applied to each middle mold 29 and each polycarbonate resin sheet R ′, and a high frequency voltage is applied between the electrode plates 27. As a result, a high-frequency electric field is formed between the electrode plates 27, and a vigorous movement occurs in the hyperbodies inside each polycarbonate resin sheet R ′, and each polycarbonate resin sheet R ′ itself generates heat by its frictional heat. The amount of heat generated at this time is proportional to the dielectric constant ε and the dielectric loss tangent tan δ, which are physical properties specific to the member. In Example 2, since the polycarbonate resin sheet R ′ satisfies 0.01 <ε × tan δ, only the resin material can be selectively heated without heating the mold. For this reason, both the electrode plates 27 and the high-frequency generator 28 function as temperature control means.

  Since a pressure along the vertical direction is applied to each heated polycarbonate resin sheet R ′, the shape of the transfer surface 30 is transferred to each polycarbonate resin sheet R ′, and each polycarbonate resin sheet R ′ is lenticular. The shape of the lens L is used (see FIG. 4C). For this reason, the space sandwiched between the middle mold 29 and the transfer surface 30 and the space sandwiched between the transfer surface 30 and the electrode plate 27 function as an opposing space.

  After the pressurizing step, the application of voltage by the high frequency generator 28 is stopped, and both molds 22 and 23 are cooled by a hot water circuit (not shown). As a result, the heat of each middle mold 29 and each polycarbonate resin sheet R ′ is conducted to both cooled molds 22 and 23, so that each molded polycarbonate resin sheet R ′ rapidly has a glass transition temperature Tg. Cooled to:

  After setting the glass transition temperature Tg or lower, the press head 24 is operated to raise the upper mold 22, and each molded polycarbonate resin sheet R ′ is taken out from the press mold 21, whereby each polycarbonate resin sheet R ′ is removed. Thus, four lenticular lenses L can be obtained (see FIG. 2D).

  When the present applicant actually molded the lenticular lens as described above using the press molding apparatus having the above-described configuration, each of the obtained lenticular lenses includes both the transfer surface and the opposing space. The shapes of the dies 22, 23 and the middle dies 29 were faithfully transferred.

According to this press molding apparatus 20, in addition to the effects (1) to (3) and (8) mentioned in the first embodiment, the following effects can be obtained.
(11) Since the high frequency dielectric heating method is adopted as the temperature control means, only the resin material (polycarbonate resin sheet R ′) can be selectively heated. For this reason, it is possible to shorten the time required to warm the resin material to a predetermined temperature (glass transition temperature Tg) or higher as compared to warming the resin material through the mold. Moreover, since the mold itself adjacent to the resin material is not warmed, the time required for cooling the molded resin material to a predetermined temperature or less can be shortened.
(12) Since the high frequency dielectric heating method is adopted, the resin material can be uniformly heated without causing a temperature distribution in the resin material. For this reason, the resin material can be molded with high accuracy.
(13) Since the high frequency dielectric heating method is adopted, the resin materials arranged in series with respect to the pressurizing direction can be set to the same temperature. For this reason, even if a plurality of resin molded products are molded in a single molding process, each resin molded product can be molded with high accuracy.
(14) Since a hot water circuit (not shown) is provided in the middle mold 29, the time required for heating and cooling the resin material can be shortened.

  In addition, although polycarbonate resin sheet R 'was used as a resin material, it is not limited to above-mentioned Example 2. FIG. It is sufficient that the resin material can be efficiently heated by the high-frequency dielectric heating method, and a material satisfying at least 0.01 <ε × tan δ, which is a dielectric constant ε and a dielectric loss tangent tan δ, which are electrical characteristics, is preferably 0.8. A material satisfying 05 <ε × tan δ can be used as the resin material. Examples of such a resin material include vinyl chloride, methacrylic resin, polycarbonate, and ethylene acid bicopolymer.

  In the press molding apparatus 20, when the resin material is molded, a space between the polycarbonate resin sheet R ′ and the transfer surface 30 is not in a vacuum atmosphere. Since the time required for the molding process can be shortened, the press molding apparatus 20 may be configured to mold the resin material in a vacuum atmosphere.

  In each of the above-described Examples 1 and 2, the number of middle molds is 1 or 4, but is given to the upper mold and the lower mold between the upper mold and the lower mold. What is necessary is just to form several opposing space in series with respect to a pressure direction, and it is not limited to each above-mentioned Example 1,2.

  In each of the first and second embodiments described above, the press mold is opened and closed by moving the upper mold up and down. However, the distance between the upper mold and the lower mold is relatively increased or decreased. Anything can be used, and the present invention is not limited to the first and second embodiments.

It is sectional drawing which showed typically the press molding apparatus which concerns on this invention. It is a schematic diagram for demonstrating the one molding process by a press molding apparatus, (a) shows the state by which the press metal mold | die was open | released, (b) shows the state by which the resin material and the middle metal mold | die were supplied. (C) shows a state in which the resin material is pressurized along the opening and closing direction of the press mold, and (d) shows a state in which a resin molded product is molded. It is sectional drawing which showed typically the other example of the press molding apparatus which concerns on this invention. It is a schematic diagram for demonstrating the one molding process by the press molding apparatus of another example, (a) shows the state by which the press metal mold | die was open | released, (b) is supplied with the resin material and the middle metal mold | die. (C) shows a state in which the resin material is pressed along the opening and closing direction of the press mold, and (d) shows a state in which a resin molded product is molded.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,20 Press molding apparatus 2,21 Press die 3,22 Upper die (as an opposite die) 4,23 Lower die (as an opposite die) 5,24 Press head (as a pressurizing means) 6, 25 Press stage (as pressurizing means) 7 Heater (as temperature control means) 8, 29 Middle mold 9 Medium mold body 10 Transfer surface molding part 11, 30 Transfer surface 27 Electrode (as temperature control means) Plate 28 High-frequency generator (as temperature control means) F Fresnel lens (as resin molded product) L Lenticular lens (as resin molded product) R Thermoplastic resin sheet

Claims (12)

A press mold having a pair of opposed molds provided facing each other so as to be openable and closable, and forming a facing space to which a resin material is supplied between the opposed molds; and the resin material at a predetermined temperature A press comprising temperature control means for heating and cooling, and pressurizing means for applying pressure along the opening and closing direction of the press mold to the resin material that has reached the predetermined temperature via the press mold. A molding device,
At least one or more middle molds are disposed between the opposed molds, and the middle mold has a transfer surface on at least one surface facing the opposed molds. A press forming apparatus comprising a part of the opposing space, wherein at least two opposing spaces are formed in series with respect to the opening / closing direction of the press mold.   The press molding apparatus according to claim 1, wherein a plurality of the middle dies are arranged in series with respect to the opening / closing direction of the press dies between the opposing dies.   The press molding apparatus according to claim 1, wherein the intermediate mold has the transfer surface on both surfaces.   The press molding apparatus according to claim 3, wherein the middle mold includes a transfer surface molding portion having the transfer surface on one side as a constituent member.   5. The press molding apparatus according to claim 4, wherein the middle mold is constituted by a middle mold body having the temperature control means and the transfer surface molding section attached to the middle mold body. .   The press molding apparatus according to claim 1, wherein a high-frequency dielectric heating method is adopted as the temperature control means.   7. The press molding apparatus according to claim 6, wherein the temperature control means includes an electrode provided on each of the opposed molds and a high frequency generator electrically connected to the both electrodes. .   The press molding apparatus according to claim 1, wherein the resin material is a thermoplastic resin sheet.   The press molding apparatus according to claim 1, further comprising a vacuum forming unit that places a vacuum atmosphere between the middle mold and the resin material.   The middle mold is composed of a middle mold body part and a transfer surface molding part attached to the middle mold body part and having the transfer surface on one side. The transfer surface molding part is open to the transfer surface. The gas hole is provided with gas from the middle mold main body, and the resin material is released from the transfer surface molding portion by the gas injected from the gas hole. The press molding apparatus according to claim 1.   The press molding method performed using the press molding apparatus of any one of Claim 1 thru | or 10. The resin molded product shape | molded using the press molding apparatus of any one of Claim 1 thru | or 10.

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