JP5054412B2 - Hot press molding apparatus and mold system for the same - Google Patents

Description

  The present invention relates to a hot press molding apparatus for transferring a fine pattern onto the surface of a thermoplastic plate by pressing a stamper, and a mold system for the apparatus.

  This type of hot press molding equipment is used for optical parts and high-design panels having fine shape patterns on the surface, such as light guide plates and diffusion plates for backlights of liquid crystal displays, lenses and optical disk substrates, for example. Used for molding. A structure of a mold for this type of hot press molding is disclosed in Patent Document 1, for example. According to this disclosure, a plate-like stamper is mounted on a heating / cooling plate having heating / cooling means, the stamper is heated / cooled by the heating / cooling plate, and the stamper is made of the thermoplastic resin plate via the heating / cooling plate. Pressed against the surface.

JP 2004-74769 A

  The height of the unevenness of the shape pattern transferred by this type of hot press molding is typically several μm to several tens of μm. On the other hand, the thickness of the thermoplastic resin plate, which is a workpiece, has a variation of about ± 0.1 mm. Furthermore, there is a variation of about 0.01 to 0.05 mm in the dimensions of the mold for mounting the stamper, the thickness and flatness of the stamper itself.

  Further, in the hot press molding disclosed in Patent Document 1, the stamper is pressed against the surface of the workpiece while being heated by the heating / cooling plate, and after the stamper is cooled by the heating / cooling plate, the stamper is applied to the workpiece. End pressing. Therefore, the heating / cooling plate is warped due to thermal strain during heating / cooling.

  Due to these events, the pressure distribution on the contact surface between the stamper and the workpiece becomes non-uniform at the time of molding, and a part of the stamper cannot be pressed against the workpiece with the required pressure. As a result, defects in which the pattern is not completely transferred partially occur on the surface of the workpiece.

  In order to solve this problem, several countermeasures can be considered. For example, a large pressing force greater than that required for transfer is applied. Alternatively, the heating temperature of the stamper is raised to lower the surface pressure necessary for transfer. Alternatively, the pressing time of the heated stamper to the workpiece is lengthened, the softened layer of the workpiece is enlarged, and the surface pressure required for transfer is lowered.

  However, these measures are not only desirable in terms of equipment cost, running cost, and production time, but also load the workpiece with a temperature or surface pressure that is higher than necessary, so that the swelling of the material side surface during molding increases. It is necessary to perform post-processing on the side of the expanded material after completion of molding.

  Accordingly, an object of the present invention is to make the contact state between the thermoplastic plate and the stamper uniform in hot press molding in which a concavo-convex pattern is transferred onto the surface of the thermoplastic plate.

  According to the present invention, a hot press molding apparatus for transferring a shape pattern onto a surface of a thermoplastic plate by pressing a stamper includes a bolster, a slide, and a press device having a drive device for driving the slide, and the slide Or a cylinder mechanism mounted on the bolster. The cylinder mechanism includes a cylinder having a pressure chamber filled therein with a heat transfer fluid. The cylinder has a flexible top plate. The flexible top plate has an inner surface facing the pressure chamber and an outer surface that supports the stamper. Further, the heat press molding apparatus includes a heating / cooling device that heats and cools the heat transfer fluid in the pressure chamber, and a preload device that applies a bias pressure to the pressure chamber.

  This heat press molding apparatus heats the stamper by heating the heat transfer fluid in the pressure chamber. When the temperature of the stamper is heated above the material softening temperature of the thermoplastic plate, the presser slide is lowered to Is pressed against the thermoplastic plate. At this time, the stamper is pressed against the surface of the thermoplastic plate by the internal pressure of the pressure chamber via the flexible top plate, so that the pressure distribution on the surface of the thermoplastic plate of the stamper becomes more uniform. Thereafter, the heat transfer fluid in the pressure chamber is cooled in this pressed state. When the temperature of the stamper is cooled below the material softening temperature of the thermoplastic plate, the slide rises.

  In a preferred embodiment, the cylinder mechanism is configured such that when the pressing force applied to the cylinder mechanism from the press device increases, the internal pressure of the pressure chamber increases. For example, the cylinder mechanism further includes a piston slidably inserted into the cylinder so as to vary the volume of the pressure chamber, and the piston is connected to the slide or bolster, and the pressing force applied to the piston from the slide or bolster As the pressure rises, it slides within the cylinder to reduce the volume of the pressure chamber.

  In a preferred embodiment, the heating / cooling device includes a heat exchange pipe provided in the pressure chamber, and a heating / cooling fluid supply device for supplying the heating fluid and the cooling fluid into the heat exchange pipe. Alternatively, as a modification, the heating and cooling device includes an electric heater provided in the pressure chamber, a heat exchange pipe provided in the pressure chamber, a heater power source for driving the electric heater, and a cooling fluid in the heat exchange pipe. You may have the cooling fluid supply apparatus to supply.

  In a preferred embodiment, when the slide rises to finish pressing the stamper against the thermoplastic plate, the top plate bulges outward due to the internal pressure of the pressure chamber and becomes a convex shape. Is applied to the pressure chamber as the bias pressure.

  In a preferred embodiment, a pressure sensor for detecting the internal pressure of the pressure chamber is further provided. Then, the drive device controls the movement of the slide based on the detected pressure from the pressure sensor so that the internal pressure of the pressure chamber becomes a preset pressure.

  In a preferred embodiment, a temperature sensor for detecting the temperature of the heat transfer fluid in the pressure chamber is further provided. The heating / cooling device controls the temperature of the heat transfer fluid in the pressure chamber to be a preset temperature based on the detected temperature from the temperature sensor.

  According to another aspect of the present invention, a mold system for a hot press molding apparatus for transferring a concavo-convex pattern onto a surface of a thermoplastic plate by pressing a stamper includes a cylinder mechanism, a heating / cooling apparatus, and a preload. Device.

  According to the present invention, the contact state between the thermoplastic plate and the stamper during molding is made uniform.

  Hereinafter, a hot press molding apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of a hot press molding apparatus according to an embodiment of the present invention.

  The hot press molding apparatus 100 is configured as a combination of a general-purpose press apparatus and a mold system for hot press molding. The general-purpose press device includes a bolster 102 fixed to the floor, a slide 104 disposed above the bolster 102, and a driving device 106 that drives the slide 104. When the slide 104 is driven by the driving device 106, the slide 104 moves in the vertical direction along a post (not shown) so as to approach and separate from the bolster 102. The drive device 106 includes, for example, a servo motor 108 that drives the slide 104 and a motor controller 110 that drives and controls the servo motor 108. As the driving device 106, a device using a hydraulic actuator may be used instead of a device using a servo motor as shown.

  The mold system includes two upper and lower cylinder mechanisms 112 and 114 mounted on the bolster 102 and the slide 104 so as to face each other. FIG. 2 shows an enlarged view of these two cylinder mechanisms 112 and 114. Since the two cylinder mechanisms 112 and 114 have substantially the same configuration, the above cylinder mechanism 112 will be described as an example with reference to FIGS. 1 and 2.

  The upper cylinder mechanism 112 includes a die set 116, a piston 118, a cylinder 120, and a holder 122. The die set 116 has a substantially rectangular plate shape and is fixed on the slide 104. The piston 118 has a substantially rectangular column shape and is fixed on the central portion of the die set 116. The cylinder 120 has a substantially rectangular cylindrical shape, and the bottom thereof is open. The piston 118 is inserted into the cylinder 120 from the opening at the bottom of the cylinder 120. With the inner surface of the cylinder 120 and the outer surface of the piston 118 in close contact with each other, the cylinder 120 is slidable in the vertical direction with respect to the piston 118 (in other words, the piston 118 is movable in the vertical direction with respect to the cylinder 120). To slide). The holder 122 has a substantially rectangular ring shape, is fixed on the die set 116, and is fitted on the outer periphery of the cylinder 120. The cylinder 120 can also slide in the vertical direction with respect to the holder 122. The holder 122 restrains the cylinder 120 from the outside so as not to tilt when the cylinder 120 slides.

  On the head surface of the holder 122, an annular sealing frame 144 having a vacuum packing on the head surface is attached via a spring 146. The sealing frame 144 is slidable with respect to the holder 122 and is urged downward by a spring 146. When the slide 104 is lowered and the lower frame mechanism 114 comes into contact with the sealing frame 144, a vacuum chamber is formed inside the sealing frame 144. When the slide 104 further descends, the sealing frame 144 slides upward with respect to the holder 122 while being in contact with the lower cylinder mechanism 114 by the pressing force from the spring 146. A vacuum pump and an atmosphere release valve (not shown) can freely perform vacuum suction and release to the atmosphere of the vacuum chamber.

  The cylinder 120 has a top plate 124 at its head. The top plate 124 is a flexible thin metal plate. A pressure chamber 126 is defined in the cylinder 120 by the top plate 124, the piston 118, and the side wall of the cylinder 120. The pressure chamber 126 is filled with a heat transfer fluid having high thermal conductivity (for example, a liquid such as oil or GALDEN (registered trademark)) that can be heated to a high temperature even under atmospheric pressure. The pressure chamber 126 is substantially sealed so that the heat transfer fluid does not leak out of the pressure chamber 126 even when the internal pressure of the pressure chamber 126 increases.

  The volume of the sealed pressure chamber 126 can be changed by sliding the piston 118 with respect to the cylinder 120. When the pressing force applied to the piston 118 from the slide 104 increases, the piston 118 slides toward the head of the cylinder 120 and attempts to reduce the volume of the pressure chamber 126, so that the internal pressure of the pressure chamber 126 increases. Except for the flexible top plate 124, all the walls facing the pressure chamber 126 are rigid and do not deform according to the internal pressure of the pressure chamber 126. On the other hand, when the internal pressure of the pressure chamber 126 rises, the flexible top plate 124 receives the internal pressure on the inner surface and deforms so as to bulge outward.

  As shown in FIG. 2, a flexible thin plate-like stamper 128 is fixed on the outer surface (head surface) of the head of the cylinder 120. The stamper 128 can be fixed by, for example, vacuum suction using a vacuum suction groove 130 processed on the head surface of the cylinder 120 (a vacuum pump for that is not shown), and a fixing treatment provided on the head surface of the cylinder 120. A combination with the tool 130 can be used. The stamper 128 fixed to the head of the cylinder 120 is in close contact with the outer surface of the flexible top plate 124. When the top plate 124 is deformed by the internal pressure of the pressure chamber 126, the stamper 128 is similarly deformed. At the time of hot press molding, the upper and lower stampers 128, 128 are pressed against both upper limit surfaces of the workpiece 200 which is a thermoplastic resin plate. At this time, as described above, the stampers 128 and 128 are deformed as the internal pressure of the pressure chamber 126 increases, so that the distribution of the molding pressure of the stampers 128 and 128 on the surface of the workpiece 200 becomes more uniform than in the past. .

  In the pressure chamber 126, a device for heating and cooling the heat transfer fluid filled therein is provided. In this embodiment, as an example, a plurality of heat exchange pipes 134 are arranged in the pressure chamber 126. The inlets of the plurality of heat exchange pipes 134 are connected to a supply pipe 136 laid in the die set 116 via a manifold 138 formed in the cylinder 120. The outlets of the plurality of heat exchange pipes 134 are connected to a discharge pipe 140 laid in the die set 116 via a manifold 142 formed in the cylinder 120. Further, a temperature sensor 148 for detecting the temperature of the heat transfer fluid in the pressure chamber 126 is provided in the pressure chamber 126 or on the wall surface facing the pressure chamber 126 (in this embodiment, on the head surface of the piston 118). ing.

  As shown in FIG. 1, the supply pipe 136 and the discharge pipe 140 are connected to a heating / cooling fluid supply apparatus 150. The heating / cooling fluid supply device 150 includes a fluid circulation device 152 and a control device 154. The fluid circulation device 152 supplies a temperature-controlled hot heating fluid (eg, steam, hot water, oil, etc.) and a low-temperature cooling fluid (eg, cooling water) to the supply pipe 136, and passes through the heat exchange pipe 134. The fluid that has flowed into the discharge pipe 140 is absorbed. By flowing the heating fluid and the cooling fluid alternately through the heat exchange pipe 134, the heat transfer fluid in the pressure chamber 126 can be heated and cooled. Upon receiving an output signal from the control device 154 and the temperature sensor 148, the temperature of the heat transfer fluid in the pressure chamber 126 indicated by the output signal is set to a preset temperature (a set temperature for heating and a set temperature for cooling). ), The temperature and flow rate of the heating fluid and cooling fluid supplied by the fluid circulation device 152 are controlled.

  As a modified configuration example for heating and cooling the heat transfer fluid in the pressure chamber 126, an electric heater (not shown) and a heat exchange pipe 134 are provided in the pressure chamber 126, and an external heater power source (not shown) is used during heating. The electric heater is energized and the supply of the cooling fluid to the heat exchange pipe 134 is stopped and air is supplied to the heat exchange pipe 126. At the time of cooling, the electric heater is energized and the heat exchange pipe 126 is stopped. A cooling fluid may be supplied.

  As shown in FIG. 1, a preload device 160 is connected to the pressure chamber 126 via a preload pipe 162. The preload device 162 constantly applies a predetermined bias pressure to the pressure chamber 126, and when the internal pressure of the pressure chamber 162 exceeds a predetermined allowable upper limit pressure, the preload device 162 releases the excess pressure of the pressure chamber 162 and allows the allowable upper limit pressure. To. Here, when the slide 104 is raised to finish pressing the stamper 128 against the workpiece 200 after pattern transfer is performed, the top plate 124 is moved outward by the internal pressure of the pressure chamber 126. It is a pressure (for example, about 1 MPa) of a magnitude | size required to bulge out and become convex shape. This bias pressure is lower than the pressure required for pattern transfer (for example, about 4 to 5 MPa). The allowable upper limit pressure is much higher than the pressure required for pattern transfer (for example, about 4 to 5 MPa).

  As shown in FIG. 1, a pressure sensor 164 for detecting the internal pressure of the pressure chamber 126 is provided in the pressure chamber 126 or the preload pipe 162 (preload pipe 162 in this embodiment). An output signal of the pressure sensor 164 is input to the motor controller 110 of the driving device 106. The motor controller 110 uses the servo motor 108 as a drive source so that the internal pressure of the pressure chamber 126 indicated by the output signal of the pressure sensor 164 becomes a preset internal pressure (which varies depending on the machining process). The movement of the slide 104 is controlled. As a result, the magnitude of the pressing force applied from the servo motor 108 to the slide 104 is controlled.

  3A to 3D show a flow of a processing operation performed by the hot press molding apparatus 100 having the above-described configuration.

  As shown in FIG. 3A, the workpiece 200, which is a thermoplastic resin plate before processing, is set on the lower stamper 128 with the slide 104 in the upper limit position. Thereafter, as shown in FIG. 3B, the slide 104 is lowered and the sealing frame 144 comes into contact with the lower holder 122. A vacuum chamber 170 is formed inside the sealing frame 144, and the slide 104 stops. A vacuum pump (not shown) starts evacuation of the vacuum chamber 170 and supply of the heating medium to the upper and lower heat exchange pipes 134 and 134 is started.

  Thereafter, as shown in FIG. 3C, when the temperature of the heat transfer fluid in the upper and lower pressure chambers 126 and 126 rises to a predetermined set temperature, and the degree of vacuum in the vacuum chamber 170 reaches a predetermined vacuum pressure, The slide 104 starts to descend again, and the upper and lower stampers 128, 128 press the workpiece 200 with the workpiece 200 interposed therebetween. As a result, the pressing force applied from the slide 104 and the bolster 102 to the upper and lower cylinder mechanisms 112 and 114 increases. Further, when the slide 104 continues to descend, the upper and lower pistons 118 and 118 slide relative to the upper and lower cylinders 120 and 120 to reduce the volume of the respective pressure chambers 126 and 126. The internal pressure rises higher than the bias pressure. As a result, the upper and lower flexible top plates 124, 124 receive the high internal pressure of the pressure chambers 126, 126 and try to bulge outward, so that the outer surfaces of the upper and lower stampers 128, 128 extend over the entire area. It is pressed against both surfaces of the workpiece 200 with a high uniform pressure. The internal pressures of the pressure chambers 126 and 126 are detected by the respective pressure sensors 148 and 148, and the movement of the slide 104 is adjusted so that the detected internal pressures become set pressures (pressures sufficiently high for hot press molding). Is done. During a predetermined set time, the upper and lower stampers 128 are pressed against both surfaces of the workpiece 200 with the set pressure.

  Thereafter, as shown in FIG. 3D, the supply of the cooling fluid to the upper and lower heat exchange pipes 134 is started. The pressing of the stampers 128 and 128 to the workpiece 200 at the set pressure is continued until the temperature of the heat transfer fluid in the pressure chambers 126 and 126 drops to a predetermined low temperature. Thereafter, the slide 104 rises and returns to the state shown in FIG. 3A, and the molding ends.

  In this way, by pressing the stampers 128, 128 against the surface of the workpiece 200 with the internal pressure of the pressure chambers 126, 126 via the flexible top plates 128, 128, the dimensions of the workpiece, stamper, and mold are measured. The stamper can be pressed against the surface of the workpiece 200 with a uniform pressure without being affected by the accuracy. As a result, it is possible to perform hot press molding with the minimum pressing force and heating temperature, and it is possible to reduce the equipment cost and running cost of the press molding apparatus and shorten the production time.

  Moreover, in the said embodiment, since the heat exchange member (a heat exchange pipe, an electric heater, etc.) for heating and cooling a heat-medium fluid is arrange | positioned in a pressure chamber, arrangement | positioning of a heat exchange member and switching of heating and cooling The temperature variation of the outer surface of the top plate to which the stamper is attached is small.

  Further, in the above embodiment, since the bias pressure is always applied to the pressure chamber, when the stamper is separated from the workpiece after forming, the top plate and the stamper of the pressure chamber are outside at the center. A convex shape slightly bulging out. For this reason, the workpiece is easily released from the stamper.

  As mentioned above, although embodiment of this invention was described, the said embodiment is an illustration for description of this invention, and is not the meaning which limits the scope of the present invention only to the said embodiment. Therefore, the present invention can be implemented in aspects other than the above embodiment.

The figure which shows the whole structure of the hot press molding apparatus 100 concerning one Embodiment of this invention. The figure which expands and shows the part of two cylinder mechanisms 112,114. The figure which shows the flow of the processing operation which the hot press molding apparatus 100 performs.

Explanation of symbols

100 hot press molding equipment,
DESCRIPTION OF SYMBOLS 102 Bolster 104 Slide 106 Drive apparatus 110 Motor controller 112,114 Cylinder mechanism 118 Piston 120 Cylinder 122 Holder 124 Top plate 126 Pressure chamber 128 Stamper 134 Heat exchange pipe 148 Temperature sensor 150 Heating / cooling fluid supply apparatus 154 Control apparatus 160 Preload apparatus 164 Pressure Sensor 200 Workpiece

Claims (9)

In a hot press molding apparatus (100) for pressing a stamper (128) to transfer a shape pattern onto the surface of a thermoplastic plate (200),
A pressing device having a bolster (102), a slide (104), and a driving device (106) for driving the slide;
The cylinder mechanism (112, 114) mounted on the slide or bolster has a cylinder (120) having a pressure chamber (126) filled with a heat transfer fluid inside, and the cylinder is a flexible top plate (124), and the flexible top plate includes the cylinder mechanism (112, 114) having an inner surface facing the pressure chamber and an outer surface supporting the stamper;
A heating and cooling device (134, 150) for heating and cooling the heat transfer fluid in the pressure chamber;
A preload device (160) for always applying a bias pressure to the pressure chamber during a machining operation ,
The bias pressure is lower than the pressure required to transfer the shape pattern;
Hot press molding equipment In the hot press molding apparatus according to claim 1,
When the pressing force applied to the cylinder mechanism from the press device is increased, the cylinder mechanism is configured such that the volume of the pressure chamber is reduced and the internal pressure of the pressure chamber is increased.
Hot press molding equipment. In the hot press molding apparatus according to claim 2 ,
The cylinder mechanism further includes a piston (118) slidably inserted into the cylinder so as to change the volume of the pressure chamber, and the piston is connected to the slide or bolster, and the slide or bolster When the press force applied to the piston from the rise, slide in the cylinder to reduce the volume of the pressure chamber,
Hot press molding equipment. In the hot press molding apparatus according to any one of claims 1 to 3,
The heating and cooling device includes a heat exchange pipe (134) provided in the pressure chamber, and a heating and cooling fluid supply device (150) for supplying a heating fluid and a cooling fluid into the heat exchange pipe.
Hot press molding equipment. In the hot press molding apparatus according to any one of claims 1 to 3,
The heating / cooling device supplies an electric heater provided in the pressure chamber, a heat exchange pipe provided in the pressure chamber, a heater power source for driving the electric heater, and a cooling fluid in the heat exchange pipe. A cooling fluid supply device,
Hot press molding equipment. In the hot press molding apparatus according to any one of claims 1 to 5,
The top plate bulges outward due to the internal pressure of the pressure chamber and becomes convex when the slide rises in order for the preload device to finish pressing the stamper against the thermoplastic plate. Applying the required pressure to the pressure chamber as the bias pressure,
Hot press molding equipment. In the hot press molding apparatus according to claim 2 or 3 ,
A pressure sensor (164) for detecting an internal pressure of the pressure chamber;
The driving device controls the pressing force applied to the slide so that the internal pressure of the pressure chamber becomes a preset pressure based on the detected pressure from the pressure sensor.
Press forming equipment
In the hot press molding device according to any one of claims 1 to 7,
A temperature sensor (148) for detecting the temperature of the heat transfer fluid in the pressure chamber;
The heating / cooling device has a control device that controls the temperature of the heat transfer fluid in the pressure chamber to be a preset temperature based on the detected temperature from the temperature sensor.
Press forming equipment In a mold system for a hot press molding apparatus for transferring a concavo-convex pattern onto the surface of a thermoplastic plate by pressing a stamper,
A cylinder mechanism mounted on a slide or bolster of the heat press device, the cylinder mechanism having a pressure chamber filled with a heat transfer fluid inside, the cylinder having a flexible top plate, and the flexible The top plate has an inner surface facing the pressure chamber and an outer surface supporting the stamper, and the cylinder mechanism,
A heating and cooling device for heating and cooling the heat transfer fluid in the pressure chamber;
A preload device that always applies a bias pressure to the pressure chamber during a machining operation ,
The bias pressure is lower than the pressure required to transfer the shape pattern;
Mold system.

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