JP2011206979A - Method for molding molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for molding a glossy molded article causing no "flow pattern" even if a resin material to which a brightening material is added is injected in a molding space including an uneven portion.SOLUTION: At the stage of "mold opening" or taking out the molded article by opening a mold for molding an appearance side surface and a mold for molding the opposite surface, a heater unit is advanced to heat the molds. Even after "mold closing" or closing both the molds, the molds are kept to be heated to, for example, 90 to 140°C for a short time. When the temperature of the molds reaches 140°C, the injection of the resin material including the brightening material into the molding space is started. When the injection of the resin material is finished, cooling water for cooling the molds is made to pass to lower temperatures of the molds. Finally, the temperatures of the molds are lowered to initial temperatures, and the mold is opened to take out the molded article.

Description

  The present invention relates to a molding method for producing a glossy molded product by molding a resin material containing a glittering material, and in particular, molding for molding a molded product while controlling the temperature of the mold before the resin is injected. Regarding the method.

  A molding die apparatus used for general resin molding has a pair of molds, that is, a cavity mold and a core mold. Usually, a molding die apparatus performs molding by injecting and injecting molten resin into a molding space formed between both a cavity mold and a core mold. In particular, a bright material such as aluminum powder or mica powder is added to the molded resin material in order to bring gloss to the molded product.

  In such a molding die apparatus, a so-called weld line is formed at a location where the resin flowing in the molding space of the mold joins at the time of molding, or a “flow pattern” is formed on the surface of the molded product provided with uneven portions such as letters. Has a problem that the appearance of the molded product is impaired.

  That is, a scale-like aluminum powder (aluminum pigment) such as “fish scale” is mixed into the resin as a so-called luster material in order to give gloss to the molded product. The “flow pattern” is considered to be caused by a phenomenon that the aluminum pigment falls down (tilts) without being completely aligned in a planar manner in the uneven portion of the molded product such as a step of a character. . That is, when the resin is poured into the mold, the alignment of the aluminum pigment (flakes) is disturbed in the uneven portion of the molded product, and appears as irregular reflection when viewed from the outside. As a result, the difference in appearance becomes “unevenness” and a flow pattern is generated.

  A molded product in which such a flow pattern appears on the surface impairs the appearance and reduces the commercial value. For this reason, painting for erasing this pattern is indispensable, and a new work process is required in producing a molded product. For this reason, it has been demanded to produce a resin molded product that does not show a “flow pattern” on the surface of the resin molded product.

  The one described in Patent Document 1 is a side gate type injection mold for producing a resin material-like molded product to which a glittering material is added, and the resin material is injected into a product portion that becomes a space for molding. The side gate is formed into a quadrangular shape and the corners thereof are curved. In this injection mold, the above-described weld line can be effectively prevented.

Japanese Patent No. 4120701

  However, in the molding method of a molded product using a conventional mold as represented by Patent Document 1, in particular, when an aluminum pigment is used as a glittering material in order to give gloss, molding with a step such as letters is performed. The “flow pattern” that appears on the uneven parts of the product cannot be eliminated. As described above, this “flow pattern” is considered to occur due to irregular reflection of external light because the aluminum pigment is not aligned in a planar shape in the uneven portion of the molded product.

  As a result of trial and error in order to remove the “flow pattern” generated in a molded product produced by a conventional method, the inventors have paralleled the outer surface of the molded product with the aluminum pigment to be injected into the molding space. It was predicted that the “flow pattern” could be prevented if it could be arranged in the same manner. For this reason, the technology to control the heating temperature of the mold is considered effective in order to eliminate the weld line of the molded product that has already been developed, and the "flow pattern" will not appear by controlling this temperature control more precisely. I discovered that.

  An object of the present invention is to provide a method for molding a glossy molded product in which external light does not diffusely reflect even when a resin material to which a bright material is added is injected into a molding space including an uneven portion, that is, a flow pattern does not occur on the appearance Is to provide.

In order to solve the above-mentioned problems and achieve the object of the present invention, the method for molding a glossy molded product of the present invention comprises molding a first mold for molding a surface on the appearance side of the molded product and a surface on the opposite side. This is a molding method for producing a glossy molded product by injecting a resin material containing a glittering material into a molding space formed by the second mold.
According to the molding method of the present invention, the following steps (a) to (e) are included.
(A) Heater unit disposed in the first mold when the mold is opened by opening the first mold that molds the outer side and the second mold that molds the opposite side. Advancing the step of heating the first mold,
(B) After performing “clamping” to close the first mold and the second mold, heating of the first mold is continued by the heater unit, and the temperature of the first mold is changed to the first temperature (for example, 90). C.) to a second temperature (eg 140 ° C.) for a while,
(C) a step of starting injection of a resin material containing a glittering material in the molding space when the temperature of the first mold becomes the second temperature;
(D) At the stage where the injection of the resin material including the glittering material into the molding space is completed, the heater unit is moved backward, and cooling water for cooling the first mold is passed through, and the first mold is moved to the second mold. Lowering from the temperature of the first to a first temperature;
(E) The step of opening the first mold and the second mold and taking out the molded product at the stage of completion of cooling when the first mold is lowered to the second temperature.

  According to the method for molding a glossy molded article using the mold of the present invention, the temperature of the heater unit arranged in the mold is finely adjusted in the molding process of the resin material to which the glittering material is added. The direction of the glittering material can be adjusted, and no “flow pattern” is generated on the appearance of the molded product. According to the molding method of the present invention, it is possible to obtain a molded product having no “flow pattern” on the appearance surface of the molded product and maintaining the gloss.

It is the schematic diagram which showed the whole structure of the molding die system using the molding method of embodiment of this invention. It is sectional drawing which shows the molding die apparatus which is the main structures of the molding die system of FIG. It is a block diagram which shows the structure of the temperature control apparatus which is the main structures of the molding die system of FIG. It is a figure explaining that a flow pattern comes out in the uneven part of a character, when shape | molding a molded article with the conventional method. It is a figure for demonstrating that the "flow pattern" in the uneven | corrugated | grooved part of a character is lose | eliminated when a molded article is shape | molded with the shaping | molding method of embodiment of this invention. It is a figure which shows the relationship between the procedure which shape | molds a molded article with the method of embodiment of this invention, and its temperature. FIG. 7 is a diagram (No. 1) for describing a state of a mold molding apparatus in each step of a molding procedure of a molded product illustrated in FIG. 6. FIG. 7 is a diagram (No. 2) for explaining the state of the die molding apparatus in each step of the molding procedure of the molded product shown in FIG. 6. It is a flowchart which shows the procedure which produces the metal mold | die used for embodiment of this invention.

[Configuration example of molding die system]
Hereinafter, an embodiment of the present invention (hereinafter sometimes referred to as “this example”) will be described with reference to FIGS. 1 to 9. First, the method for molding a glossy molded product according to the present invention will be described. A configuration example of the entire molding die system to which is applied will be described with reference to FIG.

  As shown in FIG. 1, a molding die system 1 in which the method for molding a glossy molded article of the present invention is implemented includes a molding die device 2, a temperature control device 3, a vacuum device 4, a chiller machine ( Water supply device) 5. The molding die system 1 has a cooling water / air control box 8 for controlling the temperature of the cylinder 17c in the molding die device 2 (see FIGS. 2 and 3).

  In addition, the resin material used in the molding die apparatus 2 of this example is resin of scaly aluminum powder (aluminum pigment) such as “fish scale” or mica powder as a so-called luster material in order to give gloss to the molded product. The one added to is used. As the resin material, for example, “Colored pellet” manufactured by Ewa Chemical Co., Ltd. is used.

  The molding die device 2 is electrically connected to the temperature control device 3 via the cooling water / air control box 8. Further, the molding die apparatus 2 includes a molding machine 6 and a mold 7. The molding machine 6 is a machine that performs mold closing and mold opening operations of the mold 7, but the molding machine 6 also has a function of injecting a molten resin material into the mold 7. The temperature control device 3 includes an input unit 31 that inputs a temperature of a heater 17a, an injection command temperature, a cooling lower limit temperature, and the like, which will be described later.

  In addition, although the example which comprised the temperature control apparatus 3 and the cooling water / air control box 8 as another apparatus was demonstrated in this example, it is not limited to this. For example, the temperature control device 3 and the cooling water / air control box 8 may be integrally configured as one device.

[Configuration Example of Molding Device 2]
Next, a specific configuration of the molding die apparatus 2 will be described with reference to FIG.
As shown in FIG. 2, the molding die apparatus 2 includes a pair of molds 7 including an upper mold (first mold) and a lower mold (second mold). Among the molds 7, the upper mold is called a cavity mold 11 and the lower mold is called a core mold 12. The cavity mold 11 and the core mold 12 are installed in a state of facing each other and have a structure that opens and closes relatively. A mounting plate 21 is disposed above the cavity mold 11.

The cavity mold 11 incorporates a cavity insert 13 as a mold body at the center thereof. A heat insulating plate 14 is provided around the cavity insert 13.
In the molding die apparatus 2 having such a configuration, a molding space 15 is formed between the cavity insert 13 and the core mold 12 in a mold closed state in which the cavity mold 11 and the core mold 12 are combined. A resin material melted from a gate (not shown) is injected and injected into the molding space 15, and the injected resin material is molded as a molded product 100 that matches the shape of the molding space 15.

  In this example, the cavity mold 11 is the first mold and the core mold 12 is the second mold. However, the present invention is not limited to this, and the core mold 12 is the first mold. It is good also as a 2nd metal mold | die.

  The cavity insert 13 is divided into a front plate 13a and a back plate 13b. The front plate 13 a has a molding part (concave mold) 15 a facing the core mold 12. A plurality of temperature sensors 16 (not shown) are provided on the front plate 13a. The temperature distribution in the front plate 13 a is detected by the plurality of temperature sensors 16. The plurality of temperature sensors 16 are electrically connected to the temperature control device 3.

  The back plate 13b of the cavity insert 13 is disposed on the back side of the front plate 13a. The back plate 13b is configured using a material having lower thermal conductivity than the front plate 13a.

  Further, the molding die device 2 is provided with three heater units 17 inside the cavity insert 13. The number of heater units 17 is not limited to three, and the number can be arbitrarily set according to the size and shape of the molded product.

  The heater unit 17 includes a heater 17a, a temperature sensor 17b, and a cylinder 17c (see FIG. 3). The heater unit 17 is disposed inside a back plate 13 b that constitutes the cavity insert 13. Although details will be described later, by controlling the temperature of the front plate 13a with the heater unit 17, it is possible to prevent the occurrence of a “flow pattern” that tends to appear on the surface of a particularly glossy molded product.

[Configuration example of temperature controller]
FIG. 3 is a block diagram of a temperature control apparatus to which the present invention is applied.
As described above, the temperature control device 3 is provided with the input unit 31 for inputting the temperature of the heater 17a, the injection command temperature, the cooling lower limit temperature, and the like. The temperature control device 3 is connected to a molding die device 2, a vacuum device 4, a chiller machine 5, and a molding machine 6.

The temperature control device 3 includes a heater temperature control unit 32, a mold temperature control unit 33, an injection command unit 34, and a cooling control unit 35.
The heater temperature control part 32 controls the temperature of each heater 17a of the three heater units 17 individually. Each heater 17a and each temperature sensor 17b of the three heater units 17 are connected to the heater temperature control unit 32.

  The heater temperature control unit 32 is supplied with heater temperature signals from the temperature sensors 17 b of the three heater units 17 and is supplied with preset temperature signals of the heaters 17 a from the input unit 31. The heater temperature control unit 32 can individually control the temperatures of the heaters 17a of the three heater units 17 based on the input signal supplied from the input unit 31 and the heater temperature signal.

  Further, the heater temperature control unit 32 can control the temperature of each heater 17 a according to the position where the plurality of heater units 17 are arranged in the mold 7. That is, the heater temperature control unit 32 controls the temperature of each heater 17a according to the distance between the heater unit 17 and a gate (resin inlet) (not shown) and the thickness of the molded product.

  Here, the heater 17a is incorporated in the heat source case. As the heater 17a, a ceramic heater capable of obtaining a high heat output in a small space is used. As a material for the heat source case, for example, BeCu (beryllium copper) is used. Thereby, the mechanical strength of the heat source case can be improved, and the heat generated from the ceramic heater can be easily transmitted to the heat source case. Needless to say, as the heater 17a, an electric heater or other various heaters may be used in addition to the ceramic heater.

  The three heater units 17 are supported by a cylinder 17c so as to be able to reciprocate. That is, the three heater units 17 can be individually moved in a direction in contact with the front plate 13a and a direction away from the front plate 13a by the cylinder 17c.

  Further, as shown in FIG. 2, a heat insulating material 18 and a stainless steel material 19 are provided on the upper portion of the heater unit 17. As the heat insulating material 18, a high temperature durability grade heat insulating plate is used. Thereby, the heat from the heater unit 17 is efficiently insulated so that the heat does not escape to the mounting plate 21 and the cavity mold 11. And the heater unit 17 which has such a structure is connected with the attachment plate 21 arrange | positioned above the cavity type | mold 11 via the cylinder 17c.

  Further, the temperatures of the three heater units 17 are individually detected by the temperature sensors 17b shown in FIG. The temperature sensor 17 b is electrically connected to the temperature control device 3.

  Further, as shown in FIG. 2, three outer frames 25 are provided in the back plate 13 b of the cavity insert 13. The outer frame 25 is installed so as to surround the side surface of each heater unit 17, and is configured as a cylindrical frame, for example. The heater unit 17 is movable in the vertical direction along the inner surface of the outer frame 25. As the material of the outer frame 25, a titanium alloy having a lower thermal conductivity than the back plate 13b is used.

  By providing the outer frame 25, the periphery of the heater unit 17 is effectively insulated. As a result, the escape of heat from the heater unit 17 to the back plate 13b can be reduced. Furthermore, the strength of the cavity insert 13 is maintained by incorporating the outer frame 25, and the deformation of the cavity insert 13 due to the internal pressure during injection can be suppressed.

  Except for the outer frame 25, a gap (air layer) may be provided between the heater unit 17 and the back plate 13b. That is, the heat of the heater unit 17 may be prevented from escaping to the back plate 13b by air insulation of the gap (air layer).

  In addition, as shown in FIG. 2, the molding die device 2 is provided with a plurality of water passages 27. The plurality of water passages 27 are arranged in the vicinity of the heater unit 17 inside the cavity insert 13. The water passage 27 is formed on the mating surface of the back plate 13b with the front plate 13a so as to surround the built-in portion of the heater unit 17. Cooling water is supplied to the water passage 27 from the cooling water / air control box 8 and the chiller machine 5 connected to the nipple 28 on the inlet side (see FIG. 1). Then, the cooling water is supplied to the water passage 27 so that the cavity insert 13 is cooled.

  Further, in this example, an O-ring 29 a is incorporated so as to surround the water passage 27 at the mating surface between the back plate 13 b and the front plate 13 a of the cavity insert 13. Thereby, leakage of water from the water passage 27 to the outside of the cavity insert 13 can be prevented. Further, an O-ring 29b is also incorporated in a contact portion of the outer frame 25 with the front plate 13a. Thereby, the penetration | invasion of the water from the water flow path 27 to the heater unit 17 can be prevented.

  In addition, as shown in FIG. 1, the molding die device 2 is electrically connected to the temperature control device 3. Then, the temperature of the heater unit 17 is controlled by the heater temperature control unit 32 of the temperature control device 3, and the temperature of the mold 7 is controlled by the mold temperature control unit 33 connected to the heater temperature control unit 32.

Further, the mold opening and closing operations of the molding machine 6 are controlled by the injection command unit 34, and the injection operation of the molten resin material P to the mold 7 is controlled.
Further, the heater temperature control unit 32 is connected to each temperature sensor 17 b provided in the heater unit 17, fetches temperature information of the heater 17 a from the temperature sensor 17 b, and outputs this temperature information to the mold temperature control unit 33. is doing.

  The mold temperature control unit 33 divides the mold 7 into a plurality of blocks and controls the temperature. Specifically, the mold temperature control unit 33 drives the cylinders 17c of the three heater units 17 individually, and controls the contact and separation between the heaters 17a and the mold 7 to thereby control the mold 7. To control the temperature.

The mold temperature control unit 33 is connected to a plurality of temperature sensors 16 provided in the cavity insert 13 and cylinders 17 c provided in the three heater units 17. The mold temperature control unit 33 receives the mold temperature signals of the cavity mold 11 from the plurality of temperature sensors 16 and the input signals such as the temperature of each heater 17a, the injection command temperature, and the cooling lower limit temperature from the input unit 31. Is done.
The mold temperature control unit 33 generates a drive signal for driving each cylinder 17c based on the mold temperature signal and the input signal. Further, the mold temperature control unit 33 outputs the generated drive signal to each cylinder 17 c of the three heater units 17.

  The heater 17a is brought into contact with or separated from the cavity insert 13 by moving each cylinder 17c of the heater unit 17 forward and backward by a drive signal from the mold temperature controller 33. As described above, the mold temperature control unit 33 individually controls the contact time and the separation time between the heater 17a and the cavity insert 13 in the three heater units 17. The contact time between the heater 17a and the mold 7 is defined as a heater advance time, and the time during which the heater 17a and the mold 7 are separated from each other is defined as a heater retreat time.

  Further, the mold temperature control unit 33 controls the contact time between the heater 17a and the cavity insert 13 by controlling each cylinder 17c according to the position where the plurality of heater units 17 are arranged in the mold 7. Yes. That is, the mold temperature control unit 33 controls the contact time between the heater 17a and the mold 7 according to the distance between the heater unit 17 and a gate (resin inlet) (not shown) and the thickness of the molded product. I have to.

  For example, when the heater 17a is moved away from the mold 7, the heat of the heater 17a is not transmitted to the mold 7, and the temperature of the mold 7 is lowered. Thereby, the cooling time for cooling the mold 7 can be shortened, and the molding cycle can be shortened.

  Further, an injection command unit 34 and a cooling control unit 35 are connected to the mold temperature control unit 33. The injection command unit 34 is connected to the injection unit 6 a of the molding machine 6. The injection command unit 34 generates an injection signal for controlling the injection unit 6a of the molding machine 6 based on the signal input from the mold temperature control unit 33 and the signal input from the input unit 31, and the injection unit 6a. Is output. A signal input from the mold temperature control unit 33 is temperature information of each block in the mold 7.

  Further, the injection unit 6a injects the molten resin material into the molding space 15 of the mold 7 based on the injection signal from the injection command unit 34, or stops the injection. The injection command unit 34 is a drive for driving the vacuum apparatus 4 connected to the injection command unit 34 based on the signal input from the mold temperature control unit 33 and the input signal input from the input unit 31. The signal is generated. The vacuum device 4 has a function of discharging gas from the molding space 15 during injection molding.

The cooling control unit 35 is connected to the chiller machine 5, and a plurality of electromagnetic valves 5 a are connected to the chiller machine 5. And the chiller machine 5 is connected to the some water flow path 27 via the some solenoid valve 5a.
And the cooling control part 35 is based on the signal input from the mold temperature control part 33, and the signal input from the input part 31, and the water flow time of the cooling water supplied to the some water flow path 27, and its water quantity Are controlled individually. Specifically, the cooling control unit 35 controls the opening / closing time of the plurality of solenoid valves 5 a connected to the chiller machine 5, thereby passing the cooling water supplied to each water passage 27 (resulting in The amount of water) can be controlled.

  Needless to say, the cooling water flow time and the amount of water in each flow channel are set by the temperature at which the molded product can be taken out from the mold, for example, based on the thermal deformation temperature of each resin. In this way, by individually controlling the flow time of the cooling water supplied to each flow path 27, the amount of water is also individually controlled, and the mold 7 and the molded product can be efficiently cooled. As a result, the cooling time for cooling the mold 7 and the molded product can be shortened, and the molding cycle can be shortened.

Next, based on FIG. 4 and FIG. 5, the resin material injection molding by normal temperature control and the injection molding method by temperature control of the present invention will be described in comparison.
<Reason for conventional normal molding and flow pattern>
FIG. 4 shows an example in which resin molding is performed by a conventional molding method that has been conventionally used. The mold 7 is heated at a constant temperature (for example, 90 ° C.) from the start of injection of the resin material to the end of molding. Yes.

  4 (a) to 4 (f) show a mold (cavity mold) 11 that forms one surface, which is the appearance surface of the molded product, and a mold (core mold) 12 that forms the other surface that is not the appearance surface of the molded product. The resin material P containing a brilliant material (for example, aluminum pigment) is injected step by step into the molding space formed. The dotted line portion indicates the position of the aluminum pigment K in the molding space.

  The example of FIG. 4 is an example in which the resin material P is injected while controlling the temperature of the cavity mold 11 which is an appearance mold to be kept constant at, for example, 90 ° C. When the normal mold temperature is 90 ° C., the skin layer S between the outer surface of the molded product and the aluminum pigment (aluminum component) K becomes relatively thin, and the aluminum component is on the surface of the outer mold (cavity mold 11). Come closer. When the aluminum pigment K is in a position close to the surface of the cavity mold 11 as a mold in this way, the skin layer S in contact with the mold cools to form a solidified layer, and the flowing core layer Flow resistance occurs between Therefore, shear stress is generated and the aluminum pigment K in the surface layer portion (skin layer S) is inclined. As a result, external light is diffusely reflected and the luminance is lowered.

FIG. 4A shows an initial stage in which the injection of the resin material P from a gate (not shown) starts, and the process proceeds to FIGS. 4B to 4F as time elapses.
FIG. 4C shows a case where the resin material P has advanced into the recess 41 such as letters formed in the lower mold (core mold 12). Since the resin material P to be injected is subjected to a force in the direction in which the resin material P travels and the vector in the lateral direction that is the direction in which the resin material P travels is strong, the resin material P travels mainly horizontally. However, as shown in FIG. 4C, if there is a concave portion 41 such as a rib under the portion where the resin material P is injected, a force toward the concave portion 41 is applied to the resin material P at the portion of the concave portion 41. For this reason, when the resin material P enters the recess 41, the aluminum pigment K also moves slightly downward in the direction toward the recess 41.

  In the example of FIG. 4, since the skin layer S is thin and the position of the aluminum pigment K is close to the surface of the cavity mold 11, the resin material P around the aluminum pigment K is cooled and hardened immediately. Therefore, the position and inclination of the aluminum pigment K are fixed in a state where the aluminum pigment K faces downward. In the conventional method shown in FIG. 4, the temperature of the cavity mold 11 which is an appearance mold is 90 ° C., which is considered to be lower than that of the method of the present invention described later in FIG.

  Subsequently, when the injection of the resin material P proceeds and proceeds from FIG. 4D to FIG. 4E beyond the recess 41, the flow of the resin material P and the aluminum pigment K again becomes a lateral flow. And as shown in FIG.4 (f), when the filling in the recessed part 41 is complete | finished, the flow which goes to a downward direction will almost be lose | eliminated and it will become a flow of a very right side. However, since the aluminum pigment K close to the surface of the cavity mold 11 has already hardened, the concave portion 41 remains facing the concave portion 41, and the difference in appearance appears as “unevenness”. That is, a “flow pattern” is generated.

<Wellless molding method according to an embodiment of the present invention>
Next, with reference to FIGS. 5 and 6 and FIGS. 7 and 8 as appropriate, the molding method based on temperature control according to the present invention which does not generate a “flow pattern” in the molded product will be described in detail. The method of the present invention shown in FIGS. 5 to 8 is referred to as a well-dress molding method with respect to the conventional normal molding method of FIG.

<Wellless molding method that does not generate "flow pattern">
First, according to the weldless molding method of the present invention shown in FIG. 5, unlike the normal molding method shown in FIG.
5 (a) to 5 (f) correspond to FIGS. 4 (a) to 4 (f), the description of the common parts is omitted, and FIG. 5 is different from the normal method of FIG. Only will be described.

  In the weldless molding method of the present invention described in FIG. 5, the mold temperature is set higher (for example, 140 ° C.) than the conventional method described in FIG. 4 (temperature constant at 90 ° C.) (see FIG. 6). Thus, when the temperature of the mold is set high, the skin layer S of the molded product becomes thick, so that the distance between the surface of the cavity mold 11 that is the external mold and the aluminum pigment K increases.

  That is, when the temperature of the cavity mold 11 is high, the cavity mold 11 sinks to a position near the inner center of the resin material P into which the aluminum pigment K is injected. Since the vicinity of the center inside the resin material P is close to the core layer that continues to flow, the aluminum pigment K is not affected by the frictional resistance of the surface of the cavity mold 11, and as a result, a plurality of aluminum pigments K are formed. Since the surfaces are arranged substantially parallel to each other and arranged neatly, high luminance can be obtained.

  In FIG. 5 (c), the resin material P reaches the recess 41, and the aluminum pigment K moves slightly downward in the direction toward the inside of the recess 41, but the aluminum pigment K continues to flow, the core of the resin material P that continues to flow. Because it is in a position close to the layer, it will remain in a hardly solidified state.

  Further, as shown in FIGS. 5D to 5E, when the injection of the resin material P proceeds, the aluminum pigment K flows in a substantially lateral direction together with the resin material P, and in the final stage of FIG. The filling in 41 is completed, and the flow toward the recess 41 hardly occurs. Accordingly, the aluminum pigment K is almost only flowing sideways, and the aluminum pigment K that has been tilted without being hardened is pushed up to the resin material P as shown in FIG. That is, the aluminum pigment K, which is slightly downward in FIG. 5 (e), returns to a state close to the original horizontal, so that external light is not irregularly reflected. Therefore, it is possible to produce a molded product that has almost no unevenness, that is, a “flow pattern” does not appear.

  As described above, according to the molding method of the present invention, since the surface of the concave portion or the convex portion such as the rib portion where the resin material P is likely to stay is heated by the heater, the flow of the resin material P is improved, and the rib A portion close to the appearance in the portion can be flowed first. For this reason, the surface side weld can be eliminated, and the surface of the molded product can be given gloss in the same manner as the mirror finish.

  In this example, the cavity mold 11 has been described as an external mold. However, the present invention is not limited to this, and the core mold 12 may be configured as an external mold.

<Temperature Control Method in Weldless Molding Method of Embodiment of the Present Invention>
The principle of the molding method of the present invention and the reason why “flow pattern” does not appear on the surface of the molded product have been described above. Subsequently, a temperature control method for realizing such molding will be described with reference to FIGS. 6, 7, and 8.

  In the weldless molding method according to the embodiment of the present invention, temperature control of the cavity mold is started when the cavity mold and the core mold are opened (this is referred to as “mold opening”). That is, when mold opening starts, as shown in FIG. 7A, the heater is advanced, and heating of the front plate 13a (see FIG. 2) of the cavity mold 11 is started.

  7B, the heating of the front plate 13a of the cavity mold 11 is continued as shown in FIG. 6, and the mold temperature rises for a while as shown by the temperature curve of FIG. . In other words, the mold temperature, which is 90 ° C., which is the first temperature when the mold is opened, is controlled so as to be raised to 140 ° C., which is the second temperature, at the time of “mold closing” before the start of resin injection.

  At this stage, as shown in FIG. 7C, the injection of the resin material P including the glittering material is started from a gate (not shown). While the resin material P is being injected from the mold closed state, the heater unit 17 is kept in the advanced state, and the temperature of the mold at this time is controlled to be kept constant at 140 ° C. Then, after the resin material P is filled in the entire molding space, as shown in FIG. 8D, the heater unit 17 is retracted, the filling of the resin material P is completed, and the injection is completed.

  In addition, during the predetermined time after the completion of the injection from the predetermined time before the completion of the injection, the cooling water is supplied to the cavity mold 11 from the water passage 27 to control the mold temperature so as not to rise too much (FIG. 8 ( E)). Then, when the injection is performed, the mold temperature also drops for a while, and when the mold temperature reaches about 100 ° C., the cooling water flow from the water passage 27 is stopped.

  The mold temperature drops for a while to a temperature of about 90 ° C. even after the cooling water flow is stopped. Then, mold opening for taking out the molded product is performed (see FIGS. 8F and 7A). When the mold is opened, the heater unit 17 is advanced to heat the cavity mold 11. Thereby, the heating time of the metal mold | die 7 in the following shaping | molding cycle can be shortened. Then, as shown in FIG. 7B, the molded product 100 is removed from the mold, and the process returns to the first stage again.

  As shown in FIG. 6, in the weldless molding method, the mold temperature is raised from 90 ° C. to 140 ° C. over a predetermined time, and the resin material P is injected into the molding space when the mold temperature is 140 ° C. The temperature is controlled so as to follow the process of cooling the mold temperature to 90 ° C. again. This temperature control can be realized by controlling the temperature of a plurality of (or a single) heater unit shown in FIG. 2 within a range of 400 ° C. to 300 ° C. as indicated by a dotted line.

  In this example, the example in which the first temperature is set to 90 ° C. and the second temperature is set to 140 ° C. has been described. However, the present invention is not limited to this, and the first temperature and the second temperature are set. The temperature is appropriately set according to the type of the resin material P.

<Procedure to complete the mold>
FIG. 9 is a flowchart showing a procedure for designing and manufacturing dies (cavity mold and core mold) used in the molding method of the present invention.

  First, a three-dimensional model of a molded product is determined, and a flow analysis is performed on the shape of the molded product on a computer (step S1). This flow analysis is a simulation analysis for analyzing what kind of problems occur when the molten resin material P is injected into the molding space on a computer. A study is conducted to identify countermeasures for points (step S2).

  When the confirmation of the problem and the examination of the countermeasure are completed in step S2, a simulation analysis for confirming the effect is performed on the countermeasure, and it is determined whether or not the problem has been solved (step S3). If it is determined in step S3 that the problem is not resolved, the process returns to step S2 and a new countermeasure is examined.

  If it is determined in step S3 that the problem has been resolved, the countermeasure studied in step S2 is proposed (step S4), and then it is determined whether the proposed countermeasure content is functionally usable. (Step S5). Here, the fact that it can be used functionally means that proper formability can be confirmed in terms of flow patterns, sink marks, weld positions and other appearances, short circuits, warpage, gate balance, and the like. When it is determined in step S5 that the countermeasure contents are functionally unusable, the process returns to step S2 again to examine a new countermeasure. On the other hand, when it is determined in step S5 that the countermeasure is functionally usable, the mold is designed and prototyped (step S6).

  Next, the problem is confirmed again using the prototype created in step S6, and the actual state of the prototype is reproduced by flow analysis, and various countermeasures are examined (step S7). Then, it is determined whether or not the problem has been solved by the countermeasure in the same manner as in step S3 (step S8).

  In addition, when this flow analysis is performed, it is possible to predict a location where a “flow pattern” is likely to occur on the appearance of the molded product, for example, a portion where uneven portions such as ribs and letters and a resin merge. And you may design so that the heater unit 17 may be provided in the location where the predicted "flow pattern" is easy to generate | occur | produce. Furthermore, by performing flow analysis, in addition to the position and shape of the gate for injecting the resin, the thickness of the molded product and the injection speed and pressure when the resin is poured into the mold are also considered.

  If it is determined in step S8 that the problem has not yet been resolved, the process returns to step S7 again, and new countermeasures are studied. If it is determined that the problem has been resolved, the process proceeds to step S7. The considered countermeasure is proposed (step S9).

  Then, it is determined whether or not the content of the proposed countermeasure in step S7 is functionally usable (step S10). When it is determined in step S10 that the countermeasure content is functionally unusable, the process returns to step S7 again, and the countermeasure is reexamined. On the other hand, when it is determined in step S10 that the countermeasure is functionally usable, the mold is corrected and prototyped, and all problems are confirmed (step S11).

  Finally, it is determined whether or not all the problems have been solved (step S12), and it is determined that the problems have been solved, and the mold is completed for the first time. That is, the prototype and the corrected mold are regarded as finished products (step S13). If it is determined in step S12 that at least one unsolved problem remains, the process returns to step S7 again and a method for solving the problem is examined.

  As described above, FIG. 9 describes the flow analysis and the procedure until the mold is completed when the mold of the present invention is manufactured. This procedure is merely an example, and the mold of the present invention is used. It is not directly related to the method of forming a molded product by using it.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various applications and modifications can be made without departing from the gist of the present invention described in the claims. Of course, examples are included. In the embodiment described above,

  DESCRIPTION OF SYMBOLS 1 ... Molding die system, 2 ... Molding die apparatus, 3 ... Temperature control apparatus, 4 ... Vacuum apparatus, 5 ... Chiller machine (water supply apparatus), 5a ... Solenoid valve, 6 ... Molding machine, 6a ... Injection part, 7 ... Mold, 8 ... Cooling water / air control box, 11 ... Cavity mold (first mold), 12 ... Core mold (second mold), 13 ... Cavity nesting, 13a ... Front plate, 13b ... Back plate, DESCRIPTION OF SYMBOLS 15 ... Molding space, 16 ... Temperature sensor, 17 ... Heater unit, 17a ... Heater, 17b ... Temperature sensor, 17c ... Cylinder, 18 ... Heat insulation material, 19 ... Stainless steel material, 27 ... Water passage, 31 ... Input part, 32 ... Heater temperature control unit, 33 ... mold temperature control unit, 34 ... injection command unit, 35 ... cooling control unit,

Claims (2)

Glossy molding by injecting a resin material containing a glittering material into the molding space formed by the first mold that molds the outer surface of the molded product and the second mold that molds the opposite surface. A method for forming a glossy molded product,
A step of heating the first mold by advancing a heater unit disposed in the first mold when the first mold and the second mold are opened and the mold is opened to take out the molded product; When,
After closing the first mold and the second mold, the heating of the first mold is continued by the heater unit, and the temperature of the first mold is changed from the first temperature to the second temperature. Step for a while until the temperature of
Starting injection of a resin material containing the glittering material into the molding space when the temperature of the first mold becomes the second temperature;
When the injection of the resin material including the glittering material into the molding space is completed, the heater unit is retracted and cooling water for cooling the first mold is passed, and the first mold Lowering from the second temperature to the first temperature;
Opening the first mold and the second mold and taking out a molded product at the stage of completion of cooling when the first mold is lowered to the second temperature;
A method for forming a glossy molded article including   The method of forming a molded article according to claim 1, wherein the first temperature is about 90 ° C and the second temperature is about 140 ° C.

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