JP4674241B2 - Method for heating molding mold and method for producing resin molded product - Google Patents

Description

  The present invention relates to a heating system and a heating method for a molding die, and a method for manufacturing a resin molded product, and particularly, a molding suitably used for molding a resin molded product by injection molding or transfer molding using a thermoplastic resin material. The present invention relates to a novel mold heating system, an improvement of a heating method for such a molding die, and a method for advantageously producing a resin molded product while heating the molding die by such a heating method.

  Conventionally, there are various types of molding molds for molding a resin molded product made of a thermoplastic resin material, which are appropriately selected and used according to the molding method of the target resin molded product. Yes. For example, when injection molding or transfer molding is performed, a resin molded product is molded by allowing molten resin to flow along the cavity surface of the molding die, filling the molding cavity, and solidifying. Are used.

  In such a molding die, since the resin material is filled in the molding cavity in a molten state, even if the target resin molded product has a complicated shape, the die is damaged. Such resin molded products can be mass-produced without causing problems such as these. However, when there is a joining point of molten resin in the molding cavity, a weld line often occurs on the surface of the molded resin molded product.

  Under such circumstances, a heating device such as a heater or a Peltier element is embedded inside the joining cavity surface portion of the molding die located at the location where the molten resin joins in the molding cavity. There has been proposed a molding die heating system in which a confluence cavity surface portion, which is a part of a cavity surface of a mold, is heated to a temperature higher than other portions (for example, Patent Document 1 and Patent Document 1 below) 2). According to such a heating system, the molten resin flowing in the molding cavity can be merged while maintaining a high temperature, whereby the merged molten resins are well fused, and thus Prevention of the generation of weld lines on the surface of the finally obtained resin molded product can be effectively achieved.

  However, it has been extremely difficult to efficiently heat the confluence cavity surface portion with the conventional heating system for the mold.

  That is, in the conventional heating system that uses a heater as a heating device, after the mold is opened and the resin molded product is taken out, heating of the joining cavity surface portion by the heater is started. This is continued until filling of the molten resin into the molding cavity is completed. In addition, while the heating of the joining cavity surface portion by the heater is continued, the heating temperature of the heater is controlled so that the temperature of the joining cavity surface portion is maintained at a predetermined temperature higher than that of the other cavity surface portions. Is done. Then, upon completion of the filling of the molten resin into the molding cavity, heating by the heater is terminated, and at the same time, cooling water is supplied into a cooling circuit provided in the vicinity of the heater inside the molding die, The merge cavity surface portion is cooled. Thereafter, the supply of cooling water into the cooling circuit is stopped simultaneously with the start of mold opening of the molding die. And after a resin molded product is taken out from the inside of a metal mold | die, the heating of a heater is started again and the heating and cooling operation of the above-mentioned joining cavity surface part is performed repeatedly.

  In the heating system used as a heating device for the Peltier element, when the mold closing of the molding die is completed, the part on the side of the merging cavity surface of the Peltier element generates heat, and the heat generation action causes the merging action. The cavity surface portion is heated and continues until the filling of the molten resin into the molding cavity is complete. In addition, while the merging cavity surface part is continuously heated by the Peltier element, the heat generation temperature of the Peltier element is maintained so that the temperature of the merging cavity surface part is maintained at a predetermined temperature higher than the other cavity surface parts. Is controlled. Subsequently, when the molten resin is filled into the molding cavity, the portion of the Peltier element on the side of the joining cavity surface is switched from heat generation to heat absorption, and the temperature of the joining cavity surface portion is lowered by the endothermic action. Thereafter, power supply to the Peltier element is stopped simultaneously with the start of the mold opening. Then, after the resin molded product is taken out from the mold and the mold is closed, the Peltier element is energized again, and the heating and cooling operations for the merging cavity surface portion as described above are repeatedly performed. It has become so.

  As described above, in each of the conventional mold heating systems, the mold is opened after the mold is opened until the resin molded product is taken out from the mold. After that, until the mold is closed again, the merging cavity surface portion is not heated and not kept warm. Therefore, the temperature of the confluence cavity surface portion after the mold opening further inevitably decreases from the temperature at the time of mold opening cooled after completion of filling the molten resin into the molding cavity. Therefore, when the joined cavity surface portion is heated again during molding of the resin molded product, the temperature of the joined cavity surface portion is further lower than the set temperature at the time of cooling after completion of filling the molten resin into the molded cavity. Had to rise from temperature.

  Therefore, when such a conventional molding die heating system is adopted, more time is required to heat the joining cavity surface portion to a temperature at which a weld line can be prevented from occurring on the surface of the resin molded product. Therefore, it is inevitable that the molding cycle of the target resin molded product becomes longer and the manufacturing cost rises accordingly.

JP 7-290541 A JP 2005-193423 A

Here, the present invention has been made in the background as described above, and the problem to be solved is that a resin molded product without a weld line can be molded at a lower cost with a shorter molding cycle. to provide a method pressurizing heat of the mold to. In addition, in the present invention, a method for advantageously producing a resin molded product without a weld line by using such a method for heating a molding die is also a problem to be solved.

<1> Forming a resin molded product that is a base material of a decorative resin molded product that is decorated with a metallic tone by forming a metal thin film directly on the surface by physical vapor deposition or chemical vapor deposition. A system for heating a molding die for molding a resin molded product by causing molten resin to flow along a cavity surface, filling the molding cavity, and solidifying the molten resin (A) mold opening start detecting means for detecting the mold opening start of the molding die, (b) filling completion detecting means for detecting completion of filling of the molten resin into the molding cavity, and (c) ) A first temperature detecting means embedded in a joining cavity surface portion of the molding die located at a location where the molten resin joins in the molding cavity, and detecting a temperature of the joining cavity surface portion; (D) said A first heating means that is embedded in the joining cavity surface portion of the molding die and heats the joining cavity surface portion; and (e) a second temperature detection that detects the heating temperature of the first heating means. And (f) control of the heating temperature of the first heating means when the mold opening start of the molding die is detected by the mold opening start detecting means, and the second temperature detection The heating temperature of the first heating means is controlled so that the temperature detected by the means becomes a first set temperature set equal to or higher than the glass transition temperature of the molten resin, and the temperature of the merge cavity surface portion While the temperature detected by the first temperature detecting means is higher than the glass transition temperature of the molten resin and lower than the first set temperature. When the temperature is reached, the first heating means A first control means for terminating the control of the heating temperature; and (g) when the temperature detected by the first temperature detection means reaches the second set temperature, the heating temperature of the first heating means The control is started, and the heating temperature of the first heating means is controlled so that the temperature detected by the second temperature detecting means becomes the second set temperature, and the temperature of the merge cavity surface portion is set. While maintaining the second set temperature, when the completion of filling of the molten resin into the molding cavity is detected by the filling completion detecting means, the control of the heating temperature of the first heating means is finished. And (h) starting control of the heating temperature of the first heating means when completion of filling of the molten resin into the molding cavity is detected by the filling completion detecting means. And detection by the second temperature detection means The heating temperature of the first heating means is controlled so that the temperature becomes a third set temperature set to be equal to or lower than the glass transition temperature of the molten resin, and the temperature of the joining cavity surface portion is set to the first set temperature. The third temperature is lowered to the third set temperature, and the control of the heating temperature of the first heating means is terminated when the mold opening start detecting means is detected by the mold opening start detecting means. Control means and (i) second heating means for heating the entire molding die so that the entire temperature of the molding die is lower than the third set temperature. It was formed metal mold heating system.

<2> The first control means compares the temperature detected by the second temperature detection means with the first set temperature, and controls the heating temperature of the first heating means by ON / OFF control. The molding die heating system according to the above aspect <1>, which is configured by an ON / OFF control device that performs control.

<3> The second control means compares the temperature detected by the second temperature detection means with the second set temperature, and controls the heating temperature of the first heating means by PID control. The heating system for a molding die according to the above aspect <1> or <2>, which is configured by a first PID control device.

<4> The third control unit compares the temperature detected by the second temperature detection unit with the third set temperature, and controls the heating temperature of the first heating unit by PID control. The molding die heating system according to any one of the above aspects <1> to <3>, which is configured by a second PID control device to be performed.

<5> The filling completion detecting unit detects the completion of the clamping from the mold closed state of the molding die, and from the completion of the clamping of the molding die, The set time set to a length longer than the time required for the filling into the molding cavity to be completed is measured from the time when the completion of pressing is detected by the pressing completion detecting device. The above aspects <1> to <4, including a timer device, and detecting completion of filling of the molten resin into the molding cavity based on completion of measurement of the set time by the timer device > The heating system of the molding die as described in any one of above.

<6> Forming a resin molded product that is a base material of a decorative resin molded product that is decorated with a metallic tone by forming a metal thin film directly on the surface by physical vapor deposition or chemical vapor deposition. A method for heating a molding die for molding the resin molded product by causing the molten resin to flow along the cavity surface, filling the molding cavity, and solidifying the molten resin (A) When the molding die is opened, the temperature of the joining cavity surface portion of the molding die located at the location where the molten resin joins in the molding cavity is the glass of the molten resin. The merging cavity surface portion is heated by the first heating means embedded in the merging cavity surface portion of the molding die so as to increase toward the first set temperature set to the dislocation temperature or higher. and, raising the temperature A step of, (b) the joint cavity surface part, from the time of a second set temperature which the set in the following and the first set temperature at the glass transition temperature or higher of the molten resin, the merging cavity surface And (c) after completion of filling of the molten resin into the molding cavity, so as to maintain the temperature of the portion at the second set temperature. A step of lowering the temperature of the joining cavity surface so that the temperature of the portion drops to a third set temperature set to be equal to or lower than the glass transition temperature of the molten resin, and (d) the entire mold Heating the entirety of the molding die with a second heating means separate from the first heating means so that the temperature is lower than the third set temperature. Addition of characteristic mold Heat method.

< 7 > Resin characterized in that a molding operation of a target resin molded product is performed while heating the merging cavity surface portion of the molding die by the molding die heating method according to the above aspect < 6 >. Manufacturing method of molded products.

In the 如-out forming metal mold of the heating system to above, during the time between the start of mold opening of the mold, until the filling of the molten resin into the mold cavity is completed, i.e., the molding die While the mold is closed from the mold open state, the molten resin is allowed to flow along the cavity surface, and the filling cavity surface portion of the molding die is heated to a temperature equal to or higher than the glass transition temperature of the molten resin. It can be heated and maintained. Therefore, when the molten resin is caused to flow along the cavity surface, the molten resins that have joined in the molding cavity are well fused together, so that the weld line to the surface of the finally obtained resin molded product is obtained. Prevention of the occurrence can be effectively achieved.

And in the heating system of such a molding die , especially after the filling of the molten resin into the molding cavity is completed, when the molten resin is cooled, by the heating temperature control of the heating means by the third control means, Although the temperature of the merge cavity surface part is lowered to the third set temperature set below the glass transition temperature, from the start of mold opening, by the heating temperature control of the heating means by the first control means, The temperature of the confluence cavity surface is raised to a second set temperature that is equal to or higher than the glass transition temperature, that is, a temperature at which weld lines can be prevented from being generated on the surface of the resin molded product. Until the filling is completed, the temperature of the merging cavity surface portion is changed to the second set temperature as described above by controlling the heating temperature of the heating means by the second control means. So that the can is maintained.

Therefore, in such a heating system for the mold, unlike the conventional heating system, after the mold is opened, the temperature of the surface of the joining cavity is the same as that when the mold is opened. A further drop below the temperature can be advantageously avoided. As a result, the temperature increase width when the temperature of the joint cavity surface portion is once lowered and then raised to a temperature at which the weld line can be prevented from being generated on the resin molded product surface is effectively reduced. The time and energy expended in reheating such merged cavity face portions can be advantageously saved.

Moreover, after the mold is opened, after the mold closing is completed, or after the resin molded product is taken out, it is different from the conventional heating system in which heating of the joining cavity surface portion is started for the first time. In the above-described heating system for the molding die, when the mold opening of the molding die is started, heating of the joining cavity surface portion is started, and the mold opening operation, the resin molded product take-out operation, and the mold closing operation are performed. While effectively using the time during the process, the temperature of the confluence cavity surface becomes the second preset temperature that can prevent the occurrence of weld lines on the surface of the resin molded product at the same time as these operations. Can be raised up to. Therefore, in addition to the time required for a series of operations for molding the resin molded product, an extra time may be required for raising the temperature of the confluence cavity surface portion to the second set temperature. It can be eliminated or suppressed very effectively.

Therefore, according to 如-out forming metal mold of the heating system of nuclear, free of weld lines resin molded article, it become possible to mold the lower cost in a shorter molding cycle.

Then, the method of manufacturing the resin molded article according to the heating method and the present invention of the mold according to the invention, actions and effects substantially the same that may be achieved in a heating system 如-out forming metal mold to above The action and effect can be enjoyed extremely effectively.

  Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

  First, in FIG. 1, as an example of a resin molded product manufactured while heating a molding die in accordance with the method of the present invention, a resin molding used as a base material for an automotive interior part in which a metal thin film is formed on the surface by sputtering. The article is shown in perspective form. In this case, the resin molded product 10 is an injection molded product obtained by injection molding, and has a rectangular frame as a whole in which a rectangular window 12 is provided at the center of a rectangular flat plate having a predetermined thickness. Presents. Moreover, in this resin molded product 10, the part located in the both sides of the horizontal direction (left-right direction in FIG. 1) on both sides of the window part 12 is the vertical direction (up-down direction in FIG. 1). The vertical frame portions 14a and 14b extend in the vertical direction, and the portions located on both sides in the vertical direction with the window portion 12 interposed therebetween are horizontal frame portions 16a and 16b that extend in the horizontal direction, respectively. A surface on one side in the thickness direction of the resin molded product 10 composed of the vertical frame portions 14 and the horizontal frame portions 16 is a design surface 18, and a metal (not shown) with respect to the design surface 18. The thin film is formed by, for example, a known sputtering method or vapor deposition method.

  Incidentally, when the resin molded product 10 is manufactured, for example, a molding die 20 as shown in FIG. 2 is used.

  That is, as is apparent from FIG. 2, a molding die 20 used for manufacturing the resin molded product 10 is a fixed plate 22 that is fixed in position and a movable plate that is disposed to face the fixed plate 22 with a predetermined distance therebetween. The panel 24 has fixed molds 26 and movable molds 28 fixed to each other on the opposing surfaces of the fixed disk 22 and the movable disk 24 and arranged to face each other. Further, in the molding die 20, the movable platen 24 can be approached / separated from the fixed platen 22 by, for example, a hydraulic mechanism (not shown) of a mold clamping device. The movable mold 28 is moved close to / separated from the fixed mold 26 so that the movable mold 28 and the fixed mold 26 are closed / opened.

  As shown in FIGS. 2 and 3, a cavity forming convex portion 30 is provided at the center of the mating surface (opposing surface) of the movable die 28 with the fixed die 26, and the window of the target resin molded product 10. It has a rectangular shape corresponding to the portion 12 and protrudes integrally. In addition, a cavity forming recess 32 is formed in the center portion of the mold mating surface (opposing surface) of the fixed mold 26 with the movable mold 28 with a shape corresponding to the outer surface shape of the resin molded product 10. In this case, as the fixed mold 26 and the movable mold 28 are closed, the cavity forming convex portion 30 is plunged into the cavity forming recess 32, so that the fixed mold 26 and the movable mold 28. A molding cavity 34 having a shape corresponding to the resin molded product 10 is formed between the mold mating surfaces. That is, in this case, the molding cavity 34 is formed on the outer peripheral surface and the entire side surface of the bottom surface of the cavity forming recess 32, the entire surface of the side surface of the cavity forming convex portion 30, and the mold fitting surface of the movable die 28 with the fixed die 26. It is formed by being surrounded by a peripheral portion surrounding the cavity forming convex portion 30, and all of these surfaces are defined as a cavity surface 36.

  A sprue bush 38 that is brought into contact with the nozzle 37 of the injection device is attached to the fixed platen 22, while a sub sprue 40 is provided to the fixed mold 26. The sub sprue 40 opens at the contact surface of the stationary platen 22 with the sprue bushing 38 and the bottom surface of the cavity forming recess 32, and the sprue of the sprue bushing 38 is closed when the stationary mold 26 and the movable mold 28 are closed. 42 and the molding cavity 34 are communicated with each other.

  Thus, in the molding die 20, when molten resin (not shown) is injected from the nozzle 37 of the injection device brought into contact with the sprue bush 38 under the closed state of the fixed die 26 and the movable die 28. The molten resin passes through the sprue 42 and the sub sprue 40 and is introduced into the molding cavity 34 through the opening 44 on the molding cavity 34 side of the sub sprue 40 and is filled therewith. Then, the molten resin filled in the molding cavity 34 is cooled and solidified, whereby the target resin molded product 10 is molded.

  2 and 3, in the molding die 10, the opening 44 on the molding cavity 34 side of the sub sprue 40 has two vertical frame portions (14 a) of the target resin molded product 10. , 14b) is provided at the central portion in the longitudinal direction of the vertical frame portion forming cavity surface portion 46a formed of a part of the cavity surface 36. Therefore, the molten resin introduced into the molding cavity 34 through the opening 44 is transferred from the central portion of the vertical frame portion forming cavity surface portion 46a toward the both sides in the length direction as indicated by arrows in FIG. After being divided into two, the inside of the molding cavity 34 is caused to flow along two horizontal frame portion forming cavity surface portions 48a and 48b that give two horizontal frame portions (16a and 16b), respectively, and then the other vertical frame portion ( In the central portion in the longitudinal direction of the vertical frame portion forming cavity surface portion 46b that gives 14b), the two divided molten resins are joined again.

  Thus, in the molding die 20, the vertical frame portion (14 b) that is located on the opposite side to the side where the opening 44 of the sub sprue 40 is located with the cavity forming convex portion 30 interposed therebetween is provided. The molten resin in which the central part (the ellipse shown in FIG. 3: the area in the inner part shown in FIG. 3) of the frame part forming cavity surface part 46b is divided into two in the molding cavity 34 is joined again. The cavity surface portion 50 is used.

  Here, in order to facilitate understanding, it is assumed that the flow of the molten resin in the molding cavity 34 is a simple flow as described above, and then the central portion in the longitudinal direction of the vertical frame portion forming cavity surface portion 46b. However, when the resin molded product 10 is actually molded, for example, the shape of the target resin molded product 10, the type of the molten resin, and the opening of the sub sprue 40 are used. Depending on the overall structure of the molding die 20 including the position 44, injection conditions, etc., the flow of the molten resin in the molding cavity 34 becomes more complicated. Therefore, in the actual molding of the resin molded product 20, by performing flow analysis in consideration of the shape of the resin molded product 10, the type of molten resin, the overall structure of the molding die 20, injection conditions, etc. The formation position of the merged cavity surface portion 50 on the cavity surface 36 is determined, or a target resin molded product is formed using a molding die having a structure similar to the molding die 20 used for molding the resin molded product 10. By actually molding 10 or a similar injection-molded product, the formation position of the merged cavity surface portion 50 on the cavity surface 36 is determined.

  Thus, in the present embodiment, a special heating system is provided especially for the molding die 20 having such a structure. By this heating system, the cavity surface 36 of the molding die 20 is provided. In the above-described merged cavity surface portion 50, it is heated locally.

More specifically, as shown in FIGS. 2 to 4, the heating system for the molding die 20 includes a cartridge heater 52 as a first heating means and a first thermocouple as a first temperature detection means. 54. The cartridge heater 52 and the first thermocouple 54 have the heat generating portion and the heat sensitive portion located at the tip thereof positioned directly below the bottom surface portion of the cavity forming recess 32 that constitutes a part of the merged cavity surface portion 50. In the state, it is embedded in the surface layer portion inside the fixed mold 26. Further, the cartridge heater 52 incorporates a second thermocouple (56) as a second temperature detection means (see FIG. 5) and is electrically connected to the power supply device 58.

  Accordingly, the joining cavity surface portion 50 is heated by the cartridge heater 52 in accordance with the power supply from the power supply device 58 to the cartridge heater 52. The heating temperature of the cartridge heater 52 is detected by a second thermocouple (56) built in the cartridge heater 52, while the surface temperature of the confluence cavity surface portion 50 heated by the cartridge heater 52 is the first temperature. It is detected by the one thermocouple 54.

  The embedded depth of the cartridge heater 52 and the first thermocouple 54 in the fixed mold 26 can accurately detect the depth at which the merge cavity surface portion 50 can be sufficiently heated and the surface temperature of the merge cavity surface portion 50. The depth is not particularly limited, and is appropriately determined in consideration of the strength of the fixed mold 26 and the like. Accordingly, here, for example, the first thermocouple 54 is inserted from the depth of the first thermocouple 54 embedded in the fixed mold 26, that is, from the bottom surface portion of the cavity forming recess 32 constituting a part of the merged cavity surface portion 50. (The dimension indicated by t in FIG. 4) is about 5 mm.

  In this embodiment, as shown in FIG. 1, the cartridge heater 52 and the second thermocouple (56) built in the cartridge heater 52, and further the first thermocouple 54 and the power supply device 58 include a CPU and a ROM, respectively. And a control unit 60 mainly composed of a computer including a RAM and electrically connected thereto. Thus, the heating temperature of the cartridge heater 52 is controlled by the control unit 60 based on the temperature detected by the first thermocouple 54 or the second thermocouple (56), and the temperature of the merge cavity surface portion 50 is controlled. Moreover, the injection molding of the target resin molded product 10 is implemented under such temperature control.

  That is, as shown in FIG. 5, the control unit 60 includes an ON / OFF control device 62 as a first control means, a first PID control device 64 as a second control means, and a third control means. And a second PID control device 66. The three control devices 62, 64, and 66 all have predetermined control signals for the cartridge heater 52 based on the heater temperature detection signal output from the second thermocouple 56 built in the cartridge heater 52. Is output so that the heating temperature of the cartridge heater 52 can be controlled.

  Further, the control unit 60 sets the surface temperature of the merge cavity surface portion 50 based on the merge cavity surface portion temperature detection signal output from the first thermocouple 54 to a preset temperature (second set temperature described later). ) Has a confluence cavity surface partial temperature determination device 68 for determining whether or not it has been reached. When the joining cavity surface portion temperature determining device 68 determines that the surface temperature of the joining cavity surface portion 50 has reached a preset temperature, the joining cavity surface portion temperature determination signal is sent to the ON / OFF control device. 62 is output.

  Further, the control unit 60 has a timer device 70. The timer device 70 joins with a clamping completion detection signal that is output from a clamping completion detection device 74 provided in the clamping device 72 and detects the completion of clamping from the mold closed state of the molding die 20. When both signals of the merged cavity surface partial temperature determination signal output from the cavity surface partial temperature determination device 68 are input, a preset time, specifically, from the completion of pressing of the molding die 20 The time set to a length longer than the time required for the filling of the molten resin into the molding cavity 34 to be completed is measured. In the timer device 70, at the end of the measurement of the set time, the time measurement end signal is used as a signal for detecting the completion of the filling of the molten resin into the molding cavity 34. The data is output to both the control device 64 and the second PID control device 64. As apparent from this, here, the timer device 70 and the press-completion completion detection device 74 constitute a filling completion detection device, and the timer device 70 enters the molding cavity 34 based on the end of the time measurement. Completion of filling of the molten resin is detected.

  The mold clamping device 72 is provided with a mold opening start detecting device 76 together with the above-described pressure clamping completion detecting device 74. The mold opening start detection device 76 detects the time when the mold opening of the molding die 20 is started by the mold clamping device 72, and sends a mold opening start detection signal to the ON / OFF control device 62 of the control unit 60. And the second PID control device 66 are simultaneously output. Note that the pressure clamping completion detection device 74 and the mold opening start detection device 76 are configured by, for example, a pressure sensor that constitutes a part of a hydraulic mechanism (not shown) of the mold clamping device 72.

  Further, the injection device 78 detects an injection completion detection device 80 that detects each time an injection operation is completed, and each time measurement of the amount of resin injected is completed. A measurement completion detection device 82 is provided. In the injection device 78, a clamping completion detection signal output from the clamping completion detection device 74 of the mold clamping device 72 and a filling completion detection signal output from the timer device 70 of the control unit 60 are input. Furthermore, the completion of one injection operation is detected by the injection completion detection device 80, and the completion of one metering is detected by the measurement completion detection device 82, whereby one injection operation is performed. Is to be implemented. In addition, after the injection operation is performed once, the resin to be injected next is weighed. The injection completion detection device 80 and the measurement completion detection device 72 are configured by, for example, an encoder that detects a moving position of a screw (not shown) of the injection device 78.

  Thus, in the present embodiment, the heating operation of the molding die 20 by the heating system having the above-described structure is performed as follows in parallel with the molding operation of the target resin molded product 10. It has become. In addition, the operation procedure of the heating operation of the molding die 20 shown below is the heating performed in parallel with the second and subsequent molding operations when the molding operation of the target resin molded product 10 is repeated a plurality of times. The operation procedure was described in detail.

  That is, as shown in FIGS. 6 and 7, first, in step S <b> 1 (hereinafter, simply expressed as “S <b> 1”, the same applies to other steps), the molding die 20 is opened. At this time, a mold opening start detection signal is output from the mold opening start detection device 76 of the mold clamping device 72 at the start of the mold opening.

Then, when the mold opening start detection signal is input to the ON / OFF control device 62 of the control unit 60, the control of the heating temperature of the cartridge heater 52 by the ON / OFF control device 62 is started in S2, The temperature of the joining cavity surface portion 50 of the molding die 20 is raised to a glass transition temperature: Tg or higher of the resin material used for molding the resin molded product 10. That is, the first setting in which the temperature detected by the second thermocouple 56 built in the cartridge heater 52 is set to a temperature 10 ° C. higher than the glass transition temperature: Tg of the molten resin injected from the injection device 78, for example. The ON / OFF controller 62 compares the temperature detected by the second thermocouple 56 with the first set temperature: Tg + 10 ° C. so that the heating temperature of the cartridge heater 52 is ON so that the temperature: Tg + 10 ° C. / OFF controlled. Thus, the temperature: α of the merge cavity surface portion 50 is gradually raised toward the first set temperature: Tg + 10 ° C. Note that the entire molding die 20 is preliminarily heated at a temperature lower than the glass transition temperature: Tg of the molten resin (lower than the third set temperature) by a known heating device (not shown) constituting the second heating means. Low temperature).

  In S2, the mold opening start detection signal is input to the second PID control device 66 of the control unit 60, so that the second mold (described later) is performed before the mold 20 is opened. The PID control of the heating temperature of the cartridge heater 52 by the PID control device 66 is completed. If the molding operation of the resin molded product 10 is the first time, the second PID control device 66 is not operated before the mold is opened. Therefore, in S2, the cartridge heater by the second PID control device 66 is used. The control of the heating temperature of the cartridge heater 52 by the ON / OFF control device 62 is started without completing the control of the heating temperature of 52 at all.

  Thereafter, in S3, the temperature: α of the confluence cavity surface portion 50 that is heated by the heating of the cartridge heater 52 is sequentially detected by the first thermocouple 54, whereas it is detected in S3 in S4. The temperature of the joining cavity surface portion 50: α is not less than the glass transition temperature: Tg of the molten resin injected from the injection device 78 and the first set temperature: Tg + 10 ° C. or less, for example, 5 than the first set temperature. Whether or not the second set temperature, which is set to a temperature lower by 0 ° C .: Tg + 5 ° C., is determined at any time by the confluence cavity surface partial temperature determination device 68 of the control unit 60. If the temperature α of the merge cavity surface portion 50 is still lower than the second set temperature, this determination is NO and S3 is performed again. Until this determination is YES, that is, until it is determined by the merging cavity surface temperature determination device 68 that the temperature α of the merging cavity surface portion 50 has reached the second set temperature, S3 and S4. Is repeatedly performed.

  On the other hand, after the mold opening is performed in S1, under the control of the heating temperature of the cartridge heater 52 by the ON / OFF controller 62, the temperature of the joining cavity surface portion 50 in S3 and S4: α detection and determination operation At the same time, in S5, the resin molded product 10 molded in the previous molding operation is projected from the molding cavity 34 of the molding die 10, and then in S6, the resin molded product 10 is molded into the molding die. 10 is taken out.

  Subsequently, in S7, after the molding die 20 is closed, in S8, the closed molding die 20 is pressed and prepared so that the injection operation can be performed again. At this time, when the clamping is completed, that is, when the clamping pressure applied from the clamping device 72 to the molding mold 20 closed by the molding mold 20 reaches a predetermined level. A clamping completion detection signal is output from the clamping completion detection device 74 of the mold clamping device 72. Further, the pressing state of the molding die 20 is maintained until the molding die 20 is opened again.

  When the molding operation of the resin molded product 10 is the first time, since the molded resin molded product 10 does not exist in the molding die 20 when the mold is opened in S1, S5 and S6 The protruding operation and the removing operation of the resin molded product 10 are omitted, and after the mold opening at S1, the mold closing operation and the pressing operation at S7 and S8 are performed.

  On the other hand, when the temperature of the merge cavity surface portion 50: α becomes the second set temperature: Tg + 5 ° C. and the determination in S4 becomes YES, the merge cavity surface partial temperature determination device 68 outputs a merge cavity surface partial temperature determination signal. Is output.

When the merge cavity surface partial temperature determination signal is input to the ON / OFF control device 62 and the first PID control device 64, the heating temperature of the cartridge heater 52 by the ON / OFF control device 62 is determined in S9. At the same time, the control of the heating temperature of the cartridge heater 52 by the first PID control device 64 is started. At this time, the first PID controller 64 controls the second thermocouple 56 so that the temperature detected by the second thermocouple 56 built in the cartridge heater 52 is maintained at the second set temperature: Tg + 5 ° C. The heating temperature of the cartridge heater 52 is PID-controlled while comparing the detected temperature by the above and the second set temperature: Tg + 5 ° C. Then, the heating temperature of the cartridge heater 52 is maintained at the second set temperature: Tg + 5 ° C., and the temperature: α of the joining cavity surface portion 50 of the molding die 20 becomes the second set temperature: Tg + 5 ° C. Keep warm.

  Further, when the joining cavity surface partial temperature determination signal is input to the timer device 70 and further the pressing completion detection signal from the pressing completion detection device 74 of the mold clamping device 72 is input, in S10 the timer The device 70 starts measuring a preset time.

  The set time to be measured by the timer device 70 is longer than the time required from the completion of the clamping of the molding die 20 until the filling of the molten resin into the molding cavity 34 is completed by the injection operation. Set to Here, for example, the time from when the completion of clamping is detected by the clamping completion detection device 74 to when the completion of the injection operation is detected by the injection completion detection device of the injection device 78 is the molding die. 20 is experimentally measured in advance using a similar injection molding machine or the like, and the measurement time is set as the set time.

  Further, the merge cavity surface partial temperature determination signal from the merge cavity surface partial temperature determination device 68 and the pressure clamp completion detection signal from the pressure clamp completion detection device 74 are input to the injection device 78, and the injection completion detection device. When the completion of the previous injection operation and the completion of the measurement of the molten resin to be injected next time are detected by 80 and the weighing completion device 82, the injection operation of the molten resin from the injection device 78 is performed in S11. The molten resin is filled in the molding cavity 34 while flowing along the cavity surface 36 of the molding die 20.

  At this time, the heating temperature of the cartridge heater 52 by the first PID control device 64 is maintained at the second set temperature: Tg + 5 ° C., and the temperature: α of the joining cavity surface portion 50 of the cavity surface 36 is the second set temperature. : Tg + 5 ° C. Therefore, the molten resin flowing in the molding cavity 34 is merged while maintaining a temperature higher than the glass transition temperature at the merged cavity surface portion 50, whereby the merged molten resins are well fused. It becomes like this.

  Thereafter, in S12, the molten resin in the molding cavity 34 is cooled at a preset mold temperature. On the other hand, the measurement of the set time of the timer device 70 in S10 is completed almost simultaneously with the time when the injection operation in S11 is completed and the filling of the molten resin into the molding cavity 34 is completed. The timer device 70 outputs a time measurement end signal as a substitute signal for detecting the completion of the filling of the molten resin into the molding cavity 34.

  When such a timing end signal is input to each of the first PID control device 64 and the second PID control device 66, the heating temperature of the cartridge heater 52 by the first PID control device 64 is determined in S13. At the same time, control of the heating temperature of the cartridge heater 52 by the second PID control device 66 is started, and the temperature of the joining cavity surface portion 50 of the molding die 20 is equal to or lower than the glass transition temperature of the molten resin. It is made to descend to. That is, the temperature detected by the second thermocouple 56 incorporated in the cartridge heater 52 is, for example, a third set temperature: Tg-5 ° C., which is set to a temperature 5 ° C. lower than the glass transition temperature: Tg of the molten resin. Thus, the second PID control device 66 performs PID control of the heating temperature of the cartridge heater 52 while comparing the detected temperature by the second thermocouple 56 and the third set temperature: Tg-5 ° C. The Then, the temperature: α of the merge cavity surface portion 50 is lowered to the third set temperature: Tg−5 ° C.

  As a result, the molten resin portion located in contact with the joining cavity surface portion 50 in the molding cavity 34 is brought into contact with the cavity surface 36 portion excluding the joining cavity surface portion, that is, by the cartridge heater 52. The glass transition temperature of the molten resin: Tg ° C. or lower is cooled in the same manner as the molten resin portion that contacts the cavity surface 36 portion that is not heated at all.

  When the completion of the injection operation is detected by the injection completion detection device 80 of the injection device 78, the injection pressure is maintained for a certain time in S14 in parallel with the cooling of the molten resin in the molding cavity 34 in S12. After the holding pressure is performed in the injection device 78, the injection device 78 measures the molten resin to be injected next time in S15. Then, by completing the pressure holding operation in S14, the target resin molded product 10 is molded in the molding cavity 34.

  Thereafter, the process returns to S1 again, the mold 20 is opened, and the mold opening start detection signal from the mold opening start detecting device 76 of the mold clamping device 72 is ON with the second PID control device 66. By inputting to the / OFF control device 62, S2 and subsequent steps are performed again. Then, by performing the protruding operation and the removing operation of the resin molded product 10 from the molding die 20 in S5 and S6, one molding operation of the resin molded product 10 is completed. Further, when the molding operation of the resin molded product 10 is performed again, the steps after S7 are further continued.

  In addition, in the resin molded article 10 thus manufactured, for example, a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, an ion plating method, a thermal CVD method, a plasma CVD method, a photo CVD method, or the like. As an automotive interior part in which a metal thin film is directly formed on the design surface 18 by a chemical vapor deposition method (CVD method) or the like, and thereby the design surface 18 is decorated with a metallic tone. To be used advantageously.

  When such a molding operation of the resin molded product 10 is performed again, the temperature of the merge cavity surface portion 50 is changed from the third set temperature: Tg-5 ° C. by the ON / OFF control device 62. By the ON / OFF control of the heating temperature of the cartridge heater 52, the temperature is raised to the second set temperature: Tg + 5 ° C.

  As described above, in the present embodiment, from the injection of the molten resin by the injection device 78 until the molten resin is caused to flow along the cavity surface 36 of the molding die 20 and is filled in the molding cavity 34. The temperature of the merged cavity surface portion 50 is kept at a second set temperature Tg + 5 ° C. that is equal to or higher than the glass transition temperature of the molten resin, so that the molten resin flowing in the molding cavity 34 flows in the merged cavity surface portion 50. The molten resin is merged while maintaining a high temperature equal to or higher than the glass transition temperature, so that the merged molten resins are well fused. Therefore, generation of a weld line on the surface of the molded resin molded product 10 can be prevented very effectively.

  Further, in this embodiment, after the filling of the molten resin into the molding cavity 34 is completed, in order to cool the molten resin that contacts the merged cavity surface portion 50, the temperature of the merged cavity surface portion 50 is the glass transition of the molten resin. Third set temperature below temperature: Tg −5 ° C., but the glass transition temperature of the molten resin from when the mold 20 is opened to before the injection of the molten resin is started The temperature is raised to the above second set temperature: Tg + 5 ° C., and then, as described above, until the filling of the molten resin into the molding cavity 34 is completed, the temperature of the merge cavity surface portion 50 is set to the second set temperature. Temperature: kept at Tg + 5 ° C. Therefore, unlike the conventional method, in order to cool the molten resin contacting the merge cavity surface portion 50, the temperature of the merge cavity surface portion 50 is lowered to some extent, and then the temperature of the merge cavity surface portion 50 is decreased. Further, after the mold 20 is opened, it can be advantageously avoided that the temperature is further lowered without performing any heat retaining operation or temperature raising operation. Accordingly, the temperature increase width when the temperature of the merge cavity surface portion 50 is once lowered and then raised to a temperature at which the weld line can be prevented from being generated on the surface of the resin molded product 10 is effective. The time and energy expended in reheating such a merged cavity surface portion 50 can be advantageously saved.

  Furthermore, in the present embodiment, when the molding die 20 is opened, heating of the joining cavity surface portion is started, and at the same time as the mold opening operation, the resin molded product removal operation, and the mold closing operation, The temperature of the merge cavity surface portion 50 is a second set temperature that can prevent the generation of weld lines on the surface of the resin molded product 10 while effectively utilizing the time during the operation of Tg + 5 ° C. It is raised to. Therefore, the temperature of the merge cavity surface portion 50 is raised to the second set temperature within the time required for a series of operations for molding the desired resin molded product 10, and the merge cavity surface portion It can be effectively eliminated or suppressed that extra time is spent only for the temperature increase of 50.

  Therefore, according to this embodiment as described above, the resin molded product 10 without a weld line can be molded at a low cost in a shorter molding cycle. And when a metallic thin film is directly formed on the design surface 18 of such a resin molded product 10 to give a metallic decoration, an automobile interior part is formed. In interior parts for automobiles, a metal thin film formed not only on the design surface 18 but also on the design surface 18 can not only fully exhibit the “real feeling” of the metal, which can give a sharp impression inherent to the metal to the viewer. In addition, it is possible to effectively prevent the formation of a fine groove due to the weld line, so that a good appearance of the design surface 18 can be effectively ensured.

  Moreover, in this embodiment, at the time of mold opening, the temperature of the merge cavity surface part 50 is lowered to the third set temperature: Tg-5 ° C. set to be equal to or lower than the glass transition temperature of the molten resin. Since the temperature of the molten resin in contact with the cavity surface portion 50 is cooled to below the glass transition temperature, the resin molded body 10 portion in contact with the merged cavity surface portion 50 is hot when the mold is opened. Therefore, it is possible to advantageously eliminate the deformation. As a result, the intended resin molded product 10 can be advantageously molded with a desired shape.

  Further, in the present embodiment, the heating temperature of the cartridge heater 52 is set to be higher than the glass transition temperature of the molten resin by the ON / OFF control device 62 from the start of the mold opening of the molding die 20. ON / OFF control is performed so that one set temperature: Tg + 10 ° C., and the temperature of the merge cavity surface portion 50 is increased toward the first set temperature: Tg + 10 ° C. Therefore, for example, a temperature increase in which the temperature of the merge cavity surface portion 50 is increased toward the first set temperature: Tg + 10 ° C. while controlling the heating temperature of the cartridge heater 52 by P control, PI control, PID control, or the like. As compared with the case where the operation is performed, there is an advantage that the temperature of the joining cavity surface portion 50 can be quickly reached to the target temperature.

  Further, in this embodiment, when the temperature of the merge cavity surface portion 50 reaches the second set temperature: Tg + 5 ° C., the heating temperature of the cartridge heater 52 is controlled by the ON / OFF controller 62. The control is switched to PID control by the first PID control device 64, the heating temperature of the cartridge heater 52 is maintained at the second set temperature: Tg + 5 ° C., and the temperature of the merge cavity surface portion 50 is set to the second setting. Temperature: kept at Tg + 5 ° C. Therefore, while the heating temperature of the cartridge heater 52 is controlled by the first PID control device 64, the temperature of the merge cavity surface portion 50 is more stably maintained at the second set temperature: Tg + 5 ° C. obtain.

  Furthermore, in this embodiment, after the filling of the molten resin into the molding cavity 34 is completed, the control of the heating temperature of the cartridge heater 52 is changed from the PID control by the first PID control 64 to the second PID control device. By switching to PID control by 66, the heating temperature of the cartridge heater 52 and the temperature of the joining cavity surface portion 50 are lowered to the third set temperature: Tg-5 ° C. Therefore, the heating temperature of the cartridge heater 52 and further the temperature of the merge cavity surface portion 50 are stably lowered until the temperature reaches the third set temperature: Tg-5 ° C., and contacts the merge cavity surface portion 50. The molten resin portion to be cooled is more reliably cooled, so that deformation of the resin molded body 10 when the mold is opened can be prevented more advantageously.

  In addition, in the present embodiment, a predetermined set time is measured by the timer device 70 of the control unit 60 based on the clamping completion detection signal output from the clamping completion detection device 74 of the mold clamping device 72, and the time measurement is performed. Upon completion of the process, the completion of the filling of the molten resin into the molding cavity 34 is detected, and the heating temperature of the cartridge heater 52 is controlled by the second PID control device 66 from the PID control by the first PID control 64. It can be switched to PID control. Therefore, for example, the heating temperature of the cartridge heater 52 is controlled after a predetermined time has elapsed from the completion of filling of the molten resin into the molding cavity 34 by appropriately extending the set time measured by the timer device 70. The timing for switching from PID control by the first PID control 64 to PID control by the second PID control device 66 can be variously changed.

  The specific configuration of the present invention has been described in detail above. However, this is merely an example, and the present invention is not limited by the above description.

  For example, in the embodiment, ON / OFF control and PID control are adopted as the control methods of the first, second, and third control means for controlling the heating temperature of the cartridge heater 52. The control method of the one control means is not limited to this, and is appropriately selected from known control methods, ON / OFF control, P control, PI control, PID control, and the like. The control methods of the three control means may be the same or different from each other, and the control method of any two of the three control means is the same. May be.

  The heating means is not particularly limited to the cartridge heater 52, and any heating means may be used as long as it has a structure capable of heating the joining cavity surface portion 50. That is, as the heating means, for example, a strip heater, a sheathed heater, an electromagnetic derivative having an electromagnetic induction coil, a heating / cooling body made of a Peltier element, or the like can be used instead of or in addition to the cartridge heater 52. . In consideration of handling and cost, a heating device that can be operated with electric energy can be used effectively.

  Furthermore, if the first set temperature is equal to or higher than the glass transition temperature of the molten resin, the second setting temperature is equal to or higher than the glass transition temperature of the molten resin and equal to or lower than the first set temperature. As long as the temperature is equal to or lower than the glass transition temperature of the molten resin, the specific value is not particularly limited. Even if the first set temperature and the second set temperature are the same value, there is no problem.

  Furthermore, in the above-described embodiment, the filling completion detection unit is configured by the clamping completion detection device 74 and the timer device 70. However, the structure of the filling completion detection unit can be changed as appropriate, For example, the filling completion detection means can be configured by the injection completion detection device 80 provided in the injection device 78 or the like.

  In the above embodiment, the second temperature detecting means is configured by the second thermocouple 56 built in the cartridge heater 52. However, a thermocouple provided outside the cartridge heater 52 or a thermocouple is provided. It is also possible to configure the second temperature detecting means by using a known thermal sensor other than the above. Of course, the first temperature detecting means may be changed to a known thermal sensor other than the first thermocouple 54.

In addition, in the above embodiment, the present invention, production of the resin molded article to be applied to the substrate of the automobile interior part decorating methods及 beauty metallic for heating the injection mold is subjected Although a specific example of what is applied to the method has been shown, the present invention provides a molding die for molding a resin molded product by allowing molten resin to flow along the cavity surface, filling the molding cavity, and solidifying. for any of the methods及 beauty method for producing a variety of resin molded articles for heating, it is intended to be advantageously applied, of course.

  In addition, although not listed one by one, the present invention can be implemented in a mode with various changes, modifications, improvements, and the like based on the knowledge of those skilled in the art. It goes without saying that any one of them falls within the scope of the present invention without departing from the spirit of the invention.

It is an isometric view explanatory drawing which shows an example of the resin molded product manufactured using the shaping die heated according to this invention method . It is longitudinal cross-sectional explanatory drawing which shows an example of the shaping die heated according to this invention method . FIG. 3 is an explanatory view taken along the line III-III in FIG. 2. FIG. 4 is an enlarged explanatory view of an IV part in FIG. 2. It is a functional block diagram explaining the principal part of the control function of the heating system to which the heating method according to the present invention is applied . It is a flowchart explaining the principal part of control action of the heating system to which the heating method according to the present invention is applied . It is explanatory drawing which compares and demonstrates the principal part of the control action of the heating system to which the heating method according to this invention is applied, and molding machine operation | movement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Resin molded product 20 Molding die 34 Molding cavity 36 Cavity surface 50 Merge cavity surface part 52 Cartridge heater 54 First thermocouple 56 Second thermocouple 60 Control unit 62 ON / OFF control device 64 First PID control device 66 First Second PID control device 68 Joint cavity surface partial temperature determination device 70 Timer device 72 Mold clamping device 74 Clamping completion detection device 76 Mold opening start detection device 78 Injection device

Claims (2)

A metal thin film is directly formed on the surface by physical vapor deposition or chemical vapor deposition, thereby molding a resin molded product that is a base material for a decorative resin molded product that is decorated with a metallic tone. It is a mold and a method for heating a molding die for molding the resin molded product by allowing molten resin to flow along the cavity surface, filling the molding cavity, and solidifying.
The temperature of the joining cavity surface portion of the molding die located at the location where the molten resin joins in the molding cavity is set to be equal to or higher than the glass transition temperature of the molten resin from when the molding die is opened. In order to increase the temperature toward the first set temperature, the joining cavity surface portion is heated by a first heating means embedded in the joining cavity surface portion of the molding die to raise the temperature. Process,
When the merge cavity surface portion reaches a second set temperature that is not less than the glass transition temperature of the molten resin and not more than the first set temperature, the temperature of the merge cavity surface portion is the second temperature. Maintaining the surface of the converging cavity so as to be maintained at a set temperature of
After completion of filling of the molten resin into the molding cavity, the temperature of the surface portion of the merged cavity is reduced to a third set temperature set to be equal to or lower than the glass transition temperature of the molten resin. A step of lowering the temperature of the cavity surface,
The entire molding die is heated by a second heating means separate from the first heating means so that the entire temperature of the molding mold is lower than the third set temperature. And a process of
A method for heating a molding die, comprising: A method for producing a resin molded product, comprising: performing a molding operation of a target resin molded product while heating the merging cavity surface portion of the molding die by the method for heating a molding die according to claim 1. Method.

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