JP2011079278A - Device for molding resin molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for molding a resin molded article, which prevents a weld line from being produced during resin molding. <P>SOLUTION: The device 10 of molding the resin molded article includes a heating device 11 for heating a mold and a cooling device 20 for cooling the mold after being heated, and a heating means 15 of the heating device 11 is disposed at the producing place of the weld line A in the vicinity of a cavity 30. Furthermore, the heating device 11 includes the heating means 15, a heater unit 12 for heating the heating means 15, a thermal conductor 13 for covering the heater unit 12, and a heat insulating plate 14 for holding the thermal conductor 13. Furthermore, the heating means 15 and the mold are tightly adhered to each other through soldering. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an apparatus for molding a resin molded product that can prevent the occurrence of a weld line formed on the surface of the molded product during resin molding.

  As a device for forming general resin molded products, a male mold and a female mold are provided, and a resin material melted at a high temperature is injected into a cavity formed between the male mold and the female mold. Then, an injection molding apparatus that solidifies and forms a molded product is known. Such an injection molding apparatus includes a heating device that heats the mold to a predetermined temperature when the resin material is injected, and a cooling device that cools the mold when the resin material injected into the cavity is solidified. Yes.

  As a conventional technology for injection molding equipment, a heat medium passage is formed along the cavity in the part close to the cavity in the female mold part in order to minimize deformation and transfer unevenness of the molded product and shorten the molding time. In addition, it is possible to heat or cool the cavity forming surface side of the female mold part by flowing hot steam as a heating medium or cooling water as a cooling medium in the heat medium passage, and a gas injection path to the male mold part. There is an injection molding apparatus in which a pressurized gas can be supplied into a cavity (see Patent Document 1). The injection molding apparatus described in Patent Document 1 supplies a heat medium into the heat medium passage of the female mold, heats the cavity forming surface side of the female mold, starts temperature rise, and rises at a predetermined temperature. After stopping the temperature, a predetermined amount of molten synthetic resin is injected into the cavity, and after this injection is finished, pressurized gas is injected between the synthetic resin back surface and the cavity forming surface of the male mold to synthesize While pressing the resin surface against the cavity forming surface of the female mold and holding the pressure with the pressurized gas, the cooling medium is supplied into the heat medium passage of the female mold to provide the cavity forming surface side of the female mold. When the synthetic resin is cured and the synthetic resin is cured to some extent, the pressurized gas is discharged out of the injection molding apparatus, and when the discharge is finished, a cooling gas is injected between the back surface of the synthetic resin and the cavity forming surface of the male mold. . Since the surface of the synthetic resin injected into the cavity is pressed against the cavity forming surface of the female mold with a pressurized gas, the occurrence of sink marks on the surface of the molded product is suppressed, transferability is improved, and the appearance is poor. It is said that this problem will be solved as much as possible.

  In addition, either or both of the fixed cavity mold and the movable core mold in the injection molding machine can be heated so that the mold can be heated prior to injection and the mold can be cooled simultaneously with the completion of injection. There is a mold apparatus for an injection molding machine that includes an intermediate mold and a mold support plate, and has a heating means in the intermediate mold and a cooling means in the mold support plate (see Patent Document 2). The mold apparatus for an injection molding machine described in Patent Document 2 appropriately maintains the temperature of the cavity surface and the core surface when injecting the molten injection material, and ensures excellent fluidity and transferability. Since the mold can be rapidly cooled simultaneously with the completion of the injection, the cycle time of the injection molding can be shortened.

JP 2009-101557 A JP 2008-529858 A

  However, in a general injection molding apparatus, when there are two or more gates or there are holes in the molded product, an appearance defect called a weld line occurs at a position where the melted resin flows merge. Sometimes. This weld line is a joining point where melted resin materials join together, and is formed in a linear or cracked shape on the surface of the molded product. As shown in the schematic perspective view of FIG. There are a weld line A (see FIG. 3A) formed in the length direction, and a plurality of weld lines B (see FIG. 3B) generated around the opening 35 drilled in the molded product 34. .

  If this weld line is formed on the surface of a molded product, the appearance is impaired, and this is a fatal defect in home appliances, vehicles, decorative products, etc. where design is important. In addition, when a molded product having a weld line is coated on the surface, there may be a case where coating of the paint is generated in the region where the weld line is generated.

  Here, both the injection molding apparatus of Patent Document 1 and the mold apparatus for injection molding machine of Patent Document 2 can improve transferability, but are not intended to eliminate the weld line. , It was not enough to eliminate the weld line.

  An object of the present invention is to solve the above-described problem advantageously, and an object of the present invention is to provide a molding apparatus for a resin molded product that can prevent the occurrence of a weld line during resin molding.

  The resin molded product molding apparatus of the present invention is a resin molded product molding apparatus comprising a heating device for heating a mold and a cooling device for cooling the heated mold, wherein the heating device forms a cavity. The heating means is disposed in the vicinity of the surface of the mold to be welded and where the weld line is generated.

  The heating device can include a heating unit, a heater unit that heats the heating unit, a heat conductor that covers the heater unit, and a heat insulating plate that holds the heat conductor.

  Moreover, it is preferable that the heating means and the metal mold are in close contact with each other by soldering, and it is preferable to coat a heat insulating material around the heating means.

  The heat conductor is preferably made of any one of heat conductive materials of copper, silver, brass and aluminum.

  According to the present invention, the heating device arranges the heating means in the vicinity of the mold surface forming the cavity and at the place where the weld line is generated. Can be prevented.

  Moreover, the mold in the vicinity of the cavity can be heated more efficiently by bringing the heating means and the mold into close contact with each other by soldering.

It is sectional drawing which shows the principal part of the shaping | molding apparatus of the resin molded product which concerns on one Embodiment of this invention. It is longitudinal direction sectional drawing of the shaping | molding apparatus of FIG. It is a typical perspective view which shows the weld line which generate | occur | produced in the molded article.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a molding apparatus for a resin molded product according to the present invention will be described with reference to the drawings.

  A resin molded product molding apparatus 10 according to an embodiment of the present invention shown in cross-sectional views in FIGS. 1 and 2 is applied to an injection molding apparatus 1. The injection molding apparatus 1 injects a resin material melted at a high temperature into a cavity 30 formed between the male mold 2 and the female mold 3 of the injection molding apparatus 1 to form a molded product. The injection molding apparatus 1 includes a normal heating device that heats the male mold 2 and / or the female mold 3, and a normal cooling device that cools the male mold 2 and / or the female mold 3 after heating. However, in FIG. 1 and FIG. 2, such a normal heating device and cooling device are not shown.

  By applying the molding apparatus 10 of the present embodiment to the injection molding apparatus 1, it becomes possible to prevent the occurrence of weld lines, particularly during resin molding. Details will be described below.

  The molding apparatus 10 of the present embodiment shown in FIG. 1 includes a heating device 11 for locally heating the male mold 2 and / or the female mold 3, and after being locally heated by the heating apparatus 11. And a cooling device 20 for cooling the mold. Although the heating device 11 and the cooling device 12 of the molding apparatus 10 are shown as examples disposed on the female mold 3 side, the molding apparatus for the resin molded product of the present invention is not limited to the illustrated example, and the cavity As long as it is possible to dispose a heating means to be described later in the vicinity of the surface of the mold forming the weld line, the male mold 2 may be provided. 2 and the female mold 3 may be provided.

  FIG. 2 shows a cross-sectional view of the molding apparatus 10 of the present embodiment taken along the line II-II in FIG. As can be seen from FIG. 2, in the vicinity of the center of the cavity 30 formed between the male mold 2 and the female mold 3, there is a weld line A at the junction where the melted resin materials 31 and 31 ′ merge. It has occurred. Therefore, the molding apparatus 10 according to the embodiment of the present invention is disposed along the weld line in the vicinity of the place where the weld line is generated so that the region where the weld line is generated can be heated. Has been.

  As shown in FIG. 1, the heating device 11 of the molding device 10 has a cylindrical shape, and its tip is positioned near the surface of the female die 3 facing the cavity where the weld line A is formed. A plurality of heating means 15, a cylindrical heater section 12 for heating the heating means 15, and a heat conductor 13 that covers the heater section 12 and is in contact with the base end of the heating means 15. A rectangular cross-section casing is formed, and a heater plate 12 and a heat conductor 13 are accommodated and held in the casing. The heating means 15 penetrates a part of the heat insulating plate 14.

  The heating means 15 conducts the heat of the heater part 12 heated by heat transfer from a heat source (not shown) to the female mold 3, and the mold near the cavity 30 is heated to a predetermined heating temperature, for example, about 150 ° C. It is to be heated. The heater unit 12 may generate heat by itself. The heating means 15 is formed in a cylindrical shape and is made of a material having high thermal conductivity such as copper, silver, brass, or aluminum. The proximal end of the heating means 15 is coupled to the thermal conductor 13, and the distal end 16 is disposed in the vicinity of the cavity 30.

  In particular, it is preferable that the heat conductor 13 is formed of any one of heat conductive materials of copper, silver, brass, and aluminum. This material is made of materials such as copper, silver, brass, and aluminum. It is because the thermal conductivity to the heating means 15 can be improved by forming.

  In particular, the tip 16 of the heating means 15 is in close contact with the female die 3 by soldering in the vicinity of the cavity 30. By heating the tip 16 of the heating means 15 at a high temperature, the tip 16 of the heating means 15 and the female mold 3 are bonded in a close contact state by the solder 17. As a result, the heat of the heat conductor 13 is efficiently transmitted to the tip 16 of the heating means 15, and the female mold 3 in the vicinity of the cavity 30 can be heated to a predetermined heating temperature, for example, 150 ° C. in a short time. .

  In addition, a heat insulating material 18 is covered around the heating means 15. As a material for the heat insulating material 18, it is preferable to use a material such as glass wool, asbestos, and bakelite having excellent heat resistance and durability. By covering the periphery of the heating means 15 with the heat insulating material 18, unnecessary heat conduction from the heating means 15 to the female mold 3 can be suppressed, and the cooling efficiency of the cooling device 20 for cooling the heated mold can be increased. Can be improved.

  The cooling device 20 cools the vicinity of the heating means 15 of the female mold 3 after being heated by the heating device 11, and solidifies the synthetic resin material 31 in the cavity 30. The cooling unit 21 includes a conduit for circulating the gas, and a plurality of cooling pipes 22 connected to the conduit of the cooling unit 21 and extending to the vicinity of the surface of the female mold 3.

  Next, a method of molding a resin molded product in the resin molded product molding apparatus of the present invention will be described.

  First, a synthetic resin material 31 such as a thermoplastic resin, a thermosetting resin, or a plastic resin is melted at a high temperature, and the synthetic resin material 31 is inserted between the male mold 2 and the female mold 3 from a plurality of directions through a plurality of gates. Injection into the formed cavity 30. At this time, as shown in FIG. 2, a weld line A is generated at the junction where the melted resin materials join together.

  Next, the heater unit 12 of the heating device 11 is heated by a heat source (not shown), and the heat is transferred to the heating unit 15 so that the vicinity of the cavity 30 where the tip 16 of the heating unit 15 is located is heated to about 150 ° C. Let Thereby, the weld line A generated before the resins are completely dissolved can be melted.

  After the synthetic resin material 31 is solidified to some extent, a refrigerant is introduced into the cooling unit 21 of the cooling device 20 from a cooling source (not shown), the cooling pipe 22 is cooled to cool the female mold 3, and the solidified molded product 32 is removed from the cavity 30.

  In the above-described series of molding steps, the heating means 15 of the heating device 11 is disposed in the vicinity of the cavity 30 and at the place where the weld line A is generated, thereby preventing the occurrence of a weld line during resin molding. be able to.

  Moreover, the female die 3 in the vicinity of the cavity 30 can be heated more efficiently by bringing the heating means 15 and the female die 3 into close contact with the solder 17. In the resin molding product molding apparatus 10 of the present invention, the injection molding apparatus 1 may be provided with a vacuum apparatus that holds the cavity 30 in a vacuum state.

  Further, the cooling pipe 22 of the cooling device 20 is locally disposed in the vicinity of the cavity 30 and in the vicinity of the heating means 15 disposed in the place where the weld line A is generated. When the synthetic resin material 31 is cooled, the weld line A is generated, and the cooling of the portion melted by the heating means 15 is controlled to be an appropriate speed in relation to the cooling of the other portions. Therefore, a good molded product can be obtained without incurring new problems.

  As mentioned above, although embodiment of the shaping | molding apparatus of the resin molded product of this invention was described using drawing, the shaping | molding apparatus of the resin molded product of this invention is not limited to illustrated embodiment, It describes in specification and drawing. Many variations are possible within a certain range. 1 and 2, the embodiment of the molding apparatus for the resin molded product corresponding to the weld line A in FIG. 3A has been described. However, the weld line B shown in FIG. According to the present invention, by forming a heating means in the vicinity of the mold surface forming the cavity and where the weld line B is generated, the weld line B is not generated during resin molding. Can be prevented.

DESCRIPTION OF SYMBOLS 1 Injection molding apparatus 2 Male mold 3 Female mold 10 Molding apparatus 11 Heating apparatus 12 Heater 13 Heat conductor 14 Heat insulating material 15 Heating means 16 Tip 17 Solder 18 Heat insulating material 20 Cooling apparatus 21 Cooling part 22 Cooling pipe 30 Cavity 31 Resin Material 32 Molded product 33 Molded product 34 Molded product 35 Opening A Weld line B Weld line

Claims (5)

  In a molding apparatus for a resin molded product comprising a heating apparatus for heating a mold and a cooling apparatus for cooling the mold after heating, the heating apparatus is in the vicinity of the mold surface forming a cavity and is welded. A molding apparatus for a resin molded product, characterized in that a heating means is disposed at a location where a line is generated.   The said heating device is provided with the said heating means, the heater part which heats this heating means, the heat conductor which covers this heater part, and the heat insulation board holding this heat conductor, It is characterized by the above-mentioned. The molding apparatus of the resin molded product as described in 2.   The apparatus for molding a resin molded product according to claim 2, wherein the heating means and the mold are in close contact with each other by soldering.   The apparatus for molding a resin molded product according to claim 2 or 3, wherein a heat insulating material is coated around the heating means.   The apparatus for molding a resin molded product according to claim 2, wherein the heat conductor is made of any one of heat conductive materials of copper, silver, brass, and aluminum.

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