JP4896556B2 - Injection mold equipment - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an injection mold apparatus for obtaining a resin molded product by injecting molten resin into a mold, and in particular, an injection mold for resin microparts having a fine structure with a high aspect ratio on the surface. Relates to the device.

  Microchemical chips, microanalytical chips, light guide plates in backlights of liquid crystal displays, compact disc substrates, etc. have fine concavo-convex structures on the surface of several hundreds of micrometers (μm) to several tens of nanometers (nm). The resin product is manufactured mainly by an injection molding method in which a molten resin is injected into a mold to obtain a molded product.

  For example, in compact disc molding, since the uneven structure on the surface of the substrate is relatively shallow, with a width of about 0.5 μm and a depth of about 0.1 μm, the mold surface temperature is optimized and the mold is immediately after injection. An injection compression molding method or the like is used in which the pressure inside the cavity is increased by moving the insert in the mold, thereby transferring the mold surface structure to a resin molded product.

  On the other hand, to control the mold temperature to a constant temperature below the softening point of the resin material and transfer a fine concavo-convex structure with a high aspect ratio with a width to height ratio of 0.5 or more to the molded product, Before the resin skin layer injected therein is cooled below the softening point, it is necessary to increase the pressure of the resin in the cavity to a pressure at which the fine structure of the cavity surface can be transferred. For this reason, it is necessary to increase the resin pressure within a range allowed by the characteristics of the material and inject it into the cavity at a high speed to quickly increase the cavity internal pressure. However, in the case of a fine structure with a high aspect ratio, it is difficult to allow the resin to sufficiently flow into the bottom and corners of fine recesses, so that there is a problem that a precisely shaped finely molded product cannot be obtained. It was. Furthermore, high-speed and high-pressure injection of molten resin into the cavity causes deformation of the microstructure with a high aspect ratio formed on the cavity surface, and part of the molded product is lost due to an increase in mold release resistance during mold release. There were problems such as.

  In order to avoid this problem, the mold temperature is raised to a temperature equal to or higher than the softening point of the resin material, and after injecting the molten resin at a low pressure that does not deform the fine structure of the cavity surface, the mold is A heat cycle molding method is used in which the temperature is lowered to a temperature equal to or lower than the softening point, and the molded product is taken out.

  However, this heat cycle molding method has a problem that it takes time to raise and lower the temperature and the molding cycle time becomes long, and various technical configurations have been proposed as a solution.

  For example, in Japanese Patent Application Laid-Open No. 63-182119, a cartridge heater of electric heating means and a cooling passage by air blowing are provided inside a mold insert (in the specification, “insert”), and the mold insert can be quickly installed. A technique for controlling the temperature of the surface is disclosed.

  In Japanese Patent Laid-Open No. 06-328538, an insert forming a cavity surface is fitted and arranged in a mold, and a refrigerant liquid path is formed on the side opposite to the cavity surface of the insert and heating is performed in the refrigerant liquid path. A configuration in which a heater is arranged is disclosed.

Further, in Japanese Patent Application Laid-Open No. 11-348041, a circuit A composed of a small diameter pipe is formed at a position close to the cavity surface in the mold, and a cooling circuit B composed of a large diameter pipe is formed at a far position. When the temperature of the mold needs to be raised (at the time of filling with the molten resin), the temperature of the mold is raised only by heating the circuit A with water vapor for a predetermined time only. And a technique of repeating cooling and cooling are disclosed.
JP-A-63-182119 JP 06-328538 A JP 11-348041 A

  However, the technology disclosed in Japanese Patent Laid-Open No. 63-182119 (Patent Document 1) described above is for an electric heater for heating and a cooling medium (air) in an insert (in the specification, “insert”) that constitutes a cavity portion of a mold. Although a configuration in which the passages are provided separately is employed, there is a drawback in that energy efficiency is deteriorated because heating and cooling are repeated in the entire region of the insert. In addition, the heat flow with the surroundings of the nesting causes unnecessary heating and cooling of the mold members around the cavity, so the heat capacity increases and the cycle time cannot be shortened efficiently. There is. In addition, since the heating means and the cooling circuit are formed inside the insert, the cost of the insert itself is increased, and there is a problem that it is impossible to quickly cope with molded products of various specifications. .

  In addition, in the disclosed technology disclosed in Japanese Patent Laid-Open No. 06-328538 (Patent Document 2), the cavity is configured by a nest and the nest is directly heated and cooled to focus on efficient processing with a small heat capacity. Since the heat distribution area with heating is the same, there is still a problem in energy efficiency in the process of repeating heating and cooling every molding cycle time.

  Furthermore, the technology disclosed in Japanese Patent Application Laid-Open No. 11-348041 (Patent Document 3) employs a configuration in which the heating circuit A is disposed at a position closer to the cavity surface and the cooling circuit B is disposed at a position farther from the cavity surface. The same area is heated and cooled in the mold flow path other than near the cavity, the mold member around it, and the flow path outside the mold. .

  In addition, when this technical method is applied to a mold for transferring a fine concavo-convex structure of a micrometer unit, a cooling circuit and a heating circuit come close to each other and a temperature gradient between the circuits becomes large. Therefore, there is a problem that the pipe diameter of the heating circuit becomes relatively small and a sufficient amount of heat cannot be obtained, and the necessary amount of heat cannot be supplied quickly. Furthermore, since water or water vapor is used as a heat medium, care must be taken to ensure the airtightness of the pipeline in a small area, to arrange the heat means, and to maintain and manage them. For this reason, the manufacturing and maintenance cost is high, and the practicality is poor.

  Therefore, in order to solve the various problems described above, the injection mold of the present invention proposes the following new technical idea.

That is, an injection mold apparatus according to the present invention is an injection mold apparatus that obtains a molded product by injecting molten resin into a mold. The cooling means and the heating means for conducting heat to the side opposite to the cavity surface (hereinafter referred to as “rear face”) are arranged on the rear face side, and are arranged in a state where the respective installation areas are separated, and the cooling means and the The heat conduction between the installation area with the heating means is cut off .

  As a preferable configuration of the arrangement in which the cooling means and the heating means are divided into sections, the cooling means is arranged in the vicinity of the center portion of the back surface of the nest and the heating means is arranged in the vicinity of the peripheral portion of the cooling means. Preferably, heat insulation is performed between the cooling means and the heating means with a heat insulating material so as to prevent heat transfer.

  In addition, each of the movable side and the fixed side is characterized in that the entire structure including the nest, the cooling means, and the heating means is surrounded by a heat insulating material and heat shielded.

  There are various configurations for the cooling means, but it is preferable that the flowable refrigerant is in direct contact with the back surface of the nest to conduct heat, for example, a groove opened on the back side of the nest is used. It is good also as a structure which forms the conduit | pipe through which fluid refrigerant | coolants (for example, gas and liquid) distribute | circulate by making it closely_contact | adhere to the back surface of a nest | insert.

  Next, in each of the fixed side and movable side nests, the cooling means, and the heating means of the above configuration, the temperature gradients of the fixed side and movable side nests are symmetrical with respect to the parting surface. It is more preferable to form and arrange them. Since the temperature gradient is the same, it is preferable to control the heating and cooling time in addition to the temperature distribution.

  The present invention has the following remarkable effects by the above configuration. That is, injection molding is difficult, the outer dimensions are about 30 mm × 20 mm, the thickness is 1 mm or less, and the ratio of width to height is from several hundred μm (micrometer) to several tens of nm (nanometer) on the surface. Resin microparts such as microchemical chips and microanalytical chips having a fine concavo-convex structure with a high aspect ratio of 1: 0.5 to 1: 5 can be manufactured stably and with a short molding cycle time. it can.

  In addition, since the heating means and the cooling means are separated and configured to operate in separate circuits that are independent of each other, and insulated from each other to prevent heat transfer, efficient heating and cooling without waste Can be repeated with good response. Moreover, since the nest | insert which comprises a cavity is formed in plate shape and the cooling means is made to contact the back side directly, effective heat transfer can be performed. Furthermore, since the fixed side and the movable side are configured only by nests having substantially the same capacity, the temperature can be repeatedly raised and lowered efficiently and in a short time with a small heat capacity.

  In addition, when a liquid is used as the cooling medium, it is necessary to provide a leak-proof seal at the connection portion of the flow path in the mold in consideration of leakage. However, when a gas is used as a preferable example, it is not necessary. A simple structure can be obtained, and the heat capacity can be reduced by downsizing the circuit configuration.

  Furthermore, since the entire structure including the insert and the heating means and the cooling means is insulated to prevent heat from flowing out to the mold structural members such as the surrounding mold plate and receiving plate, it is efficient. The temperature of the nesting can be raised and lowered.

  The best mode for carrying out the invention relating to an injection mold apparatus for injecting molten resin provided in the present application into a mold to obtain a molded product is to insert a cavity mold on the movable side and the fixed side into a plate-like shape. A cooling means and a heating means for conducting heat directly to the back surface of the plate-like insert that is on the side opposite to the cavity surface of the plate-like insert are arranged along the back surface. Preferably, the cooling means is disposed in the vicinity of the central portion of the back surface of the insert, and the heating means is disposed in the peripheral portion thereof. Further, between the cooling means and the heating means, in order to block heat transfer between the means, at least one of the means is thermally insulated by surrounding it with a heat insulating material.

  In addition, the whole including the cooling means and / or the heating means and the insert, which are thermally insulated between the above means, is surrounded by a heat insulating material so as to be heat shielded as a whole.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2. FIG. 1 is a schematic longitudinal sectional view showing an injection mold apparatus according to the present invention, and FIG. 2 is a schematic longitudinal sectional view showing an enlarged main part of the present invention.

  The basic configuration of the illustrated resin injection molding machine is as follows. In the drawing, the fixed-side mounting plate 20 and the movable-side mounting plate 30 are arranged opposite to the upper and lower ends, respectively, and the fixed-side mold plate 21 is mounted on the lower surface side of the fixed-side mounting plate 20. A movable side template 31 that constitutes a parting surface in contact with and away from the fixed side template 21 is disposed. A receiving plate 32 is attached to the lower surface side of the movable side template 31, and the receiving plate 32 is supported by the movable side attaching plate 30 with a certain movable space secured by a spacer block 33. In the movable space, ejector pins 35 are arranged upright and actuated when the molded product is released when the mold is opened with the upper and lower ejector plates 34 and 34 as support bases. Reference numerals 22 and 36 denote cartridge heaters, which are arranged in appropriate positions on the fixed side mounting plate 30 and the receiving plate 32, respectively. Thereby, the temperature of each template 21, 31 is maintained at a predetermined temperature, and temperature management is performed by temperature sensors (for example, thermocouples) 23, 37 arranged in the same manner.

  The above basic configuration is not particularly the part invented in the present application and is not particularly different from that of the conventional device, and thus the detailed description of the detailed configuration is omitted.

  The main point of the present invention is the configuration of the cavity portion disposed between the contact and separation surfaces (parting surfaces) of the fixed-side template 20 and the movable-side template 31. That is, the insert 1 is used in a mold for transferring a fine uneven surface to the surface of a molded product, and the insert 1 is configured to be repeatedly raised and lowered in temperature with a small heat capacity. .

  In the present embodiment, the insert 1 is formed in a plate shape with a thickness of 3 mm, and a flow path structure (not shown) having a groove cross section with a width of 100 μm and a depth of 50 μm is formed on the surface of the fixed-side insert 1 f. A fine concavo-convex structure (not shown) is formed for transferring a wall structure having a width of 20 μm, a height of 40 μm and a length of 100 μm, and the movable side nest 1 m is a thin plate having a size of 20 mm × 20 mm and a depth of 0.4 mm. The chip outline shape for micro analysis is engraved and formed. In addition, a thermocouple 2 as a temperature sensor is embedded in the center of each of the nests 1f and 1m on the fixed side and the movable side, and the temperature of the nest is determined based on temperature information from here. Monitoring and controlling temperature rise and fall.

  For example, heating means 3 in which a cartridge heater is disposed in a block made of beryllium copper alloy is joined to the peripheral portion except for the vicinity of the central portion of the back surface of each of the movable side and fixed side inserts 1f and 1m. In addition, the portion other than the surface in contact with the insert 1 is surrounded by a heat insulating material 4 made of, for example, zirconia ceramics, and heat insulation with the cooling means 5 described later is performed together with the surroundings. As a result, the heat flow from the heating means 3 is prevented from flowing to the peripheral portion other than the insert 1 and the temperature can be raised quickly and efficiently with a small heat capacity.

  On the other hand, a cooling means 5 composed of a grooved circuit having a cross section of 2 mm in width and 2 mm in depth is brought into contact with the vicinity of the center of the back surface (on the opposite side of the cavity) of each of the nests 1f and 1m on the movable side and the fixed side. Are arranged. The pipe 6 is formed by bringing the opening side into contact with the back surface of the insert 1 in close contact with the groove circuit. This pipe line 6 has a circuit configuration in which a cooling gas as a fluid refrigerant flows in from the inflow path 7 and is discharged from the outflow path 8. Thus, since the back surface of the insert 1 bears one side surface of the pipe 6, the cooling gas directly touches the back surface, so that the temperature of the insert 1 can be lowered by efficient heat removal.

  Further, by arranging the heating means 3 in the vicinity of the edge of the back surface and the cooling means 5 in the vicinity of the center portion of the back surface, by efficiently removing heat near the center portion where heat is likely to accumulate, The temperature can be lowered with a uniform temperature distribution. In this embodiment, air, nitrogen, or helium is used as the cooling gas. However, when helium is used, the temperature lowering time can be shortened by about 30% compared to air or nitrogen.

  Further, a heat insulating material 9 made of, for example, zirconia ceramics is disposed so as to surround the entire nest 1, the heating means 3, and the cooling means 5, and the portion where the temperature rise / fall is repeated is thermally insulated from the peripheral portion. In addition, the temperature of the cavity can be increased and decreased efficiently in a short time.

  Cartridge heaters 22 and 36 and thermocouples 23 and 37 are installed on the receiving plate 31 in contact with the fixed side mounting plate 20 and the movable side template 31, respectively. The temperature is set low. As a result, the temperature of the entire mold can be stabilized and the mold M and the insert 1 can be opened and closed with high accuracy without causing deflection or distortion, thereby transferring the microstructure to the surface. The molded piece M made of a small piece of resin could be stably released without damaging it.

  In this example, PMMA resin (DELPET 560F manufactured by Asahi Kasei Chemicals Corporation) having a softening point temperature of 94 ° C. is used as the resin material, and the resin temperature is 230 ° C. and the mold temperature is 70 ° C. with the above-described mold. Before energizing the cartridge heaters (electric heaters) 22 and 36 of the heating means 3 to raise the temperature of the insert 1, the resin is applied immediately after the temperature of the movable and fixed inserts 1 f and 1 m reaches 130 ° C. Injection into the cavity. Simultaneously with the injection, energization of the electric heater as the heating means 3 is stopped, and at the same time, an electromagnetic valve (flow path opening / closing valve) for the cooling gas is opened to circulate the cooling gas to cool the nests 1f and 1m. When the nesting temperature is lowered to 80 ° C., the mold (the nesting in contact with each other) is opened, and the molded product M is ejected from the mold by the ejector pin 35 and removed. By repeating this process, a chip substrate for microanalysis could be stably molded with a molding cycle time of 30 seconds.

  In addition, the structure of the temperature control part in the vicinity of the cavity on the fixed side / movable side is configured to be symmetric with respect to the mold opening surface (parting surface). By setting the temperature distribution to be substantially the same, the deformation and distortion of the molded product M due to the difference in residual stress distribution could be suppressed. As a result, it was possible to obtain a molded product M having a high transfer accuracy without warping even though it was a 0.4 mm thin plate-shaped chip.

It is a schematic longitudinal cross-sectional view which shows the mold apparatus for injection molding which concerns on this invention. It is a schematic longitudinal cross-sectional view which expands and shows the principal part of this invention.

Explanation of symbols

1f Fixed side insert 1m Movable side insert 2 Thermocouple 3 Heating means 4 Heat insulating material 5 Cooling means 6 Pipe line 7 Inflow path 8 Outflow path 9 Heat insulating material 20 Fixed side mounting plate 21 Fixed side mold plate 22 Cartridge heater 23 Thermocouple 30 Movable side mounting plate 31 Movable side template 32 Receiving plate 33 Spacer block 34 Ejector plate 35 Ejector pin 36 Cartridge heater 37 Thermocouple M Molded product

Claims (5)

In an injection mold apparatus that obtains a molded product by injecting molten resin into a mold, a cavity mold is constituted by an insert, and a cooling means and a heating means for conducting heat to the opposite cavity surface side of the insert Is disposed on the side opposite to the cavity surface, and is disposed in a state where the respective installation areas are separated, and the heat conduction between the installation areas of the cooling means and the heating means is cut off. Mold equipment. In the cooling means and heating means and arrangement,
2. An injection mold apparatus according to claim 1, wherein the cooling means is disposed in the vicinity of the central portion of the insert opposite to the cavity side, and the heating means is disposed in the vicinity of the peripheral portion of the cooling means.   3. The mold apparatus for injection molding according to claim 1, wherein the whole including the insert, the cooling means, and the heating means is insulated and shielded.   In the configuration of the cooling means,
  4. The mold apparatus for injection molding according to claim 1, wherein the flowable refrigerant is in direct contact with the opposite cavity surface of the insert to conduct heat.   The fixed and movable side inserts, the cooling means, and the heating means are formed and arranged so that the temperature gradient of the fixed and movable side inserts is symmetrical with respect to the parting surface. 5. The mold apparatus for injection molding according to claim 1, 2, 3, or 4.

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