JP7083992B2 - Injection molding equipment and injection molding method - Google Patents

Description

The present invention relates to an injection molding apparatus and an injection molding method .

The injection molding apparatus is an apparatus for manufacturing a resin product by injecting a fluidized resin material into a molding die and solidifying the filled resin material. Such an injection molding apparatus has been widely used in the past.

For example, Patent Document 1 includes a resin melting device having a high-frequency oscillator, and the resin melting device is used to inject a fluidized resin material into a molding die to lower the temperature of the resin in the molding die. Discloses an injection molding apparatus for manufacturing resin products.

In the resin melting device disclosed in Patent Document 1, only the resin material of the drawn portion, which is the portion immediately before the resin flow direction, is heated and melted with respect to the nozzle connected to the molding die.

Further, Patent Document 2 discloses a configuration in which a heater is attached to the molding die to ensure the fluidity of the resin material injected into the molding die. As a result, the fluidity of the resin material in the molding die can be ensured, and the product quality of the resin product can be improved.

Japanese Unexamined Patent Publication No. 2014-113699 Japanese Unexamined Patent Publication No. 2000-127175

However, in the technique disclosed in Patent Document 2, it is necessary to heat and cool the entire mold in order to solidify the resin material filled in the mold, the tact time becomes long, and the energy efficiency is low. Therefore, the technique disclosed in Patent Document 2 has room for improvement from the viewpoint of production efficiency.

The present invention has been made to solve the above-mentioned problems, and by ensuring high fluidity of the resin material in the molding die, it is possible to manufacture a high-quality resin product and to produce it. It is an object of the present invention to provide an injection molding apparatus and an injection molding method capable of reducing costs.

The injection molding apparatus according to one aspect of the present invention has an injection machine that injects a resin material mixed with a dielectric heating material with fluidity by controlling the temperature, and a cavity that is a flow path of the resin material. At the same time, a high-frequency AC voltage is applied to the molding die having a pair of electrodes provided so as to each face the cavity and sandwich the resin material in a direction intersecting the flow direction, and the pair of electrodes. Each of the pair of electrodes is provided from an upstream end to a downstream end in the flow direction with respect to the cavity, and at least one of the pair of electrodes is the above-mentioned. The convexly protruding portion has a portion protruding with respect to the cavity, and at least the corner portion of the convexly protruding portion is formed of a curved surface, and the high frequency is generated when the entire cavity is filled with the resin material. When the impedance value of the high-frequency AC voltage applied by the oscillating device is set to a predetermined impedance value, the high-frequency oscillating device sets the impedance value to the predetermined impedance value from the initial stage of injecting the resin material into the cavity to the completion of filling. The fixed high frequency AC voltage is applied.

In the injection molding apparatus according to the above aspect, a resin material mixed with a dielectric heating material is used as the resin material to be injected, a pair of electrodes facing the cavity are provided, and a high frequency AC voltage is applied between the pair of electrodes. It is configured to do. Therefore, in the injection molding apparatus according to the above aspect, it is possible to control the high frequency AC voltage applied to the resin material injected from the injection machine and flowing in the cavity, and the resin material applies the high frequency AC voltage. High fluidity is ensured by the control of.

Here, when a thermoplastic resin material is used as the injection resin material, the dielectric heating material generates heat due to the high-frequency AC voltage applied to the resin material flowing in the cavity, which causes the resin material. It is possible to secure the fluidity of.

On the other hand, when a thermosetting resin material is used as the injection resin material, the dielectric heating material generates heat due to the high-frequency AC voltage applied while the resin material is filled in the cavity. The resin material can be cured.

Further, in the injection molding apparatus according to the above aspect, the fluidity is ensured by controlling the temperature of the resin material flowing in the cavity instead of heating the entire molding mold, so that energy loss can be reduced. At the same time, the resin material can be solidified only by controlling the high-frequency AC voltage applied after the resin material is filled in the cavity, so the tact time can be shortened compared to the case of controlling the temperature of the entire molding die. You can also.

Further, in the injection molding apparatus according to the above aspect, since the pair of electrodes are provided from the upstream end to the downstream end in the flow direction of the resin material in the cavity, the temperature of the resin material is controlled over the entire area in the cavity. can do.

Further , in the injection molding apparatus according to the above aspect, the impedance value of the high frequency AC voltage is fixed to the predetermined impedance value from the initial stage of injection of the resin material into the cavity to the completion of filling, so that the control is simplified. At the same time, accurate control is possible even in the injection of resin material at high speed.
Further, in the injection molding apparatus according to the above aspect, since the corner portion of the convexly protruding portion of the electrode is formed of a curved surface, the air discharge in the cavity when a high frequency AC voltage is applied between the electrodes The occurrence can be suppressed. Therefore, in the injection molding apparatus according to the above aspect, the life of the electrode and the high frequency oscillator can be extended.

Therefore, in the injection molding apparatus according to the above aspect, it is possible to manufacture a high quality resin product by ensuring high fluidity of the resin material in the molding die, and it is possible to reduce the production cost.

The injection molding apparatus according to another aspect of the present invention is the above-mentioned embodiment, wherein each of the molding dies has a mold body and has a fixed mold and a movable mold that are fitted to each other, and the pair of electrodes. One of the electrodes is attached to the fixed mold body with an insulator interposed therebetween, and the other electrode of the pair of electrodes is an insulator to the movable mold body. It is attached by sandwiching.

In the injection molding apparatus according to the above aspect, in both the fixed type and the movable type, the electrodes are attached to the mold body with the insulator sandwiched between them, so that the electrodes are attached to the outside of the mold when a high frequency AC voltage is applied. It is possible to suppress the leakage of electromagnetic waves.

In the injection molding apparatus according to another aspect of the present invention, when each of the fixed mold and the movable mold is viewed in a plan view from the mold clamping direction of both molds, the insulator is attached to the electrode. Also has a large size.

In the injection molding apparatus according to the above aspect, since the size of the insulator is larger than that of the electrode in a plan view, when a high frequency AC voltage is applied to the electrode from the high frequency oscillating device, the electrode and the mold body It is possible to suppress creeping discharge between the two.

The injection molding apparatus according to another aspect of the present invention has the above aspect, wherein at least one of the pair of electrodes has a cooling passage through which a cooling medium flows, and the cooling medium is supplied to the cooling passage. Further equipped with a cooling medium supply device.

In the injection molding apparatus according to the above aspect, since the electrode is provided with a cooling passage, even if the heat of the resin material due to the dielectric heat generation is transferred to the electrode, the electrode can be cooled by supplying the cooling medium. Therefore, in the injection molding apparatus according to the above aspect, the temperature of the resin material flowing in the cavity can be adjusted more accurately, and the resin material is supplied by supplying a cooling medium when the resin material is solidified and taken out from the molding die. And the molding mold can be cooled, and the tact time can be shortened. Therefore, the injection molding apparatus according to the above aspect is advantageous in achieving higher productivity.

The injection molding apparatus according to another aspect of the present invention further comprises a control unit for controlling injection of the resin material from the injection machine and application of the high frequency AC voltage by the high frequency oscillating device. The control unit controls the injection machine so that the injection pressure is continuously applied to the cavity for a predetermined time after the resin material is filled in the entire cavity.

In the injection molding apparatus according to the above aspect, since the holding pressure period (predetermined time) is provided after the resin material is filled in the cavity, the resin material in the entire cavity is covered until the resin material is solidified. The pressure can be made uniform. Therefore, in the injection molding apparatus according to the above aspect, the shrinkage of the resin material at the time of solidification can be made uniform over the entire cavity, which is advantageous for producing a high quality resin product.

The injection molding apparatus according to another aspect of the present invention is the above embodiment, wherein the high frequency oscillating device includes an oscillator and a matching device, and a pair of feeder lines provided for connecting the matching device and the pair of electrodes. , And at least one of the pair of feeder lines is configured by using a band-shaped conductive member.

Since the injection molding apparatus according to the above aspect employs a band-shaped conductive member for the feeder line, it is possible to reduce the loss when a high frequency AC voltage is applied between the matching device and the electrodes. As a result, the injection molding apparatus according to the above aspect can be driven with high energy efficiency and can suppress the occurrence of heat generation unevenness of the resin material.

In the injection molding method according to one aspect of the present invention, an injection step of injecting a resin material mixed with a dielectric heating material with fluidity by controlling the temperature and the resin material injected in the injection step are used. The molding die comprises a flow step for flowing in the cavity formed in the molding die and a high frequency AC voltage applying step for applying a high frequency AC voltage to the resin material flowing in the cavity. , Each facing the cavity, each being provided from the upstream end to the downstream end in the flow direction with respect to the cavity, and sandwiching the resin material in a direction intersecting the flow direction. The pair of electrodes provided in the above, at least one of the pair of electrodes has a portion that protrudes convexly with respect to the cavity, and the portion that protrudes convexly has at least a corner portion. In the high-frequency AC voltage application step, which is composed of a curved surface, the high-frequency AC voltage is applied to the resin material that flows from the upstream end to the downstream end in the flow direction in the cavity, and the entire cavity is applied. When the impedance value of the high-frequency AC voltage applied in the high-frequency AC voltage application step is set to a predetermined impedance value when the resin material is filled in the cavity, the resin material is applied to the cavity in the high-frequency AC voltage application step. The high-frequency AC voltage with the impedance value fixed at the predetermined impedance value is applied from the initial stage of injecting the battery to the completion of filling.

In the injection molding method according to the above aspect, a resin material mixed with a dielectric heating material is used as the resin material to be injected, and a high frequency AC voltage can be applied to the resin material flowing in the cavity in the high frequency AC voltage application step. It has a similar structure. Therefore, in the injection molding method according to the above aspect, the high frequency AC voltage applied to the resin material injected from the injection machine and flowing in the cavity is controlled so that the resin material flowing in the cavity is applied with high frequency. High fluidity is ensured by controlling the AC voltage.

Here, similarly to the above, when the base material adopts a thermoplastic resin material as the injection resin material, the dielectric heating material generates heat due to the high frequency AC voltage applied to the resin material flowing in the cavity. As a result, the fluidity of the resin material can be ensured.

On the other hand, when a thermosetting resin material is used as the injection resin material, the dielectric heating material generates heat due to the high-frequency AC voltage applied while the resin material is filled in the cavity. The resin material can be cured.

Further, in the injection molding method according to the above aspect, the temperature of the resin material flowing in the cavity is controlled in the high frequency AC voltage application step instead of heating the entire molding mold to secure the fluidity of the resin material. Therefore, energy loss can be reduced, and the resin material can be solidified only by controlling the high-frequency AC voltage applied after the resin material is filled in the cavity, so that the temperature of the entire molding die can be reduced. It is also possible to shorten the tact time as compared with the case of controlling.

Further, in the injection molding method according to the above aspect, since the pair of electrodes are provided from the upstream end to the downstream end in the flow direction of the resin material in the cavity, the entire area in the cavity is covered in the high frequency AC voltage application step. The temperature of the resin material can be controlled.

Further , in the injection molding method according to the above aspect, in the application of the high frequency AC voltage in the step of applying the high frequency AC voltage, the impedance value of the high frequency AC voltage to be applied is set from the initial stage of injection of the resin material to the cavity to the completion of filling. Since it is fixed to the predetermined impedance value, the control can be simplified and accurate control can be performed even in the injection of the resin material at high speed.
Further, in the injection molding method according to the above aspect, in the molding die used, since the corner portion of the convexly protruding portion of the electrode is formed by a curved surface, the inside of the cavity when a high frequency AC voltage is applied between the electrodes. It is possible to suppress the occurrence of air discharge in. Therefore, in the injection molding apparatus according to the above aspect, the life of the electrode and the high frequency oscillator can be extended.

Therefore, in the injection molding method according to the above aspect, it is possible to manufacture a high-quality resin product by ensuring high fluidity of the resin material in the molding mold, and it is possible to reduce the production cost.

The injection molding method according to another aspect of the present invention is the above-mentioned aspect, in which the resin material is filled in the entire cavity in the injection step, and then the injection pressure is continuously applied to the cavity for a predetermined time. Further prepare for steps.

In the injection molding method according to the above aspect, since the pressure holding step is provided, the pressure of the resin material is made uniform in the entire area of the cavity after the resin material is filled in the cavity until the resin material solidifies. be able to. Therefore, in the injection molding method according to the above aspect, the shrinkage of the resin material at the time of solidification can be made uniform over the entire cavity, which is advantageous for producing a high-quality resin product.

The injection molding method according to another aspect of the present invention is the above aspect, in which the resin material filled in the cavity is cooled to a cooling passage provided in the molding mold after the execution of the pressure holding step. A cooling step of cooling by supplying a medium is further provided.

In the injection molding method according to the above aspect, since the cooling step is provided, even if the heat of the resin material due to the dielectric heat generation is transferred to the electrode, the electrode can be cooled by executing the cooling step. Therefore, in the injection molding method according to the above aspect, the temperature of the resin material flowing in the cavity can be adjusted more accurately, and the resin material is supplied by supplying a cooling medium when the resin material is solidified and taken out from the molding die. And the molding mold can be cooled, and the tact time can be shortened. Therefore, the injection molding method according to the above aspect is advantageous in achieving higher productivity.

In the technique according to each of the above aspects, it is possible to manufacture a high-quality resin product by ensuring high fluidity of the resin material in the molding die, and it is possible to reduce the production cost.

It is a schematic diagram which shows the structure of the injection molding apparatus which concerns on embodiment. It is a schematic cross-sectional view which shows a part of the structure of a molding die. It is a schematic diagram which shows the structure of the cavity formed in the mold. It is a schematic cross-sectional view which shows the IV-IV cross section of FIG. It is a schematic diagram which shows the heat generation principle of a resin material. It is a time chart which shows the control form of a high frequency voltage and injection pressure executed by the control part of an injection molding apparatus. It is a schematic diagram which shows the temperature and pressure of the resin material in a molding die at the time of injection. It is a schematic diagram which shows the temperature and pressure of the resin material in a molding mold at the time of holding pressure. (A) is a schematic diagram modeling a circuit configuration related to application of a high-frequency AC voltage in an injection molding apparatus, and (b) is a work when the amount of resin material flows when the voltage between electrodes is assumed to be constant. It is a characteristic diagram which shows the relationship between a cross-sectional area and a calorific value. It is a chemical formula of a dielectric exothermic material. (A) is a schematic diagram showing a state before the movement of cations in the dielectric exothermic material, and (b) is a schematic diagram showing a state after the cations have moved in the dielectric exothermic material. It is a schematic perspective view which shows the appearance structure of the molding die provided in the injection molding apparatus. It is a schematic cross-sectional view which shows the XIII-XIII cross section of FIG. It is a schematic cross-sectional view which shows the arrangement form of an electrode and an insulator with respect to a mold body. It is a schematic perspective view which shows the form of the feed line connected to the electrode.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the form described below is an aspect of the present invention, and the present invention is not limited to any of the following forms except for its essential configuration.

Hereinafter, embodiments will be described with reference to the drawings. It should be noted that the form described below is an aspect of the present invention, and the present invention is not limited to any of the following forms except for its essential configuration.

[Embodiment]
1. 1. Configuration of Injection Molding Device 1 The configuration of the injection molding device 1 according to the present embodiment will be described with reference to FIG.

As shown in FIG. 1, the injection molding apparatus 1 according to the present embodiment includes a molding die 10, an injection unit (injection machine) 20, a high frequency oscillation unit (high frequency oscillation device) 30, and a control unit 60. ..

The molding die 10 has a movable die 11 and a fixed die 12, and a cavity 10a is formed between the movable die 11 and the fixed die 12. The movable mold 11 can be clamped and separated from the fixed mold 12 by a drive mechanism (not shown).

The movable mold 11 is an insulator inserted between the mold main body 111 made of a metal material, the electrode 112 provided in a state facing the cavity 10a with respect to the mold main body 111, and the mold main body 111 and the electrode 112. 113 and. Inside the electrode 112, a cooling pipe 114 through which a cooling liquid (cooling medium) flows is embedded.

The fixed mold 12 is an insulator inserted between the mold main body 121 made of a metal material, the electrode 122 provided so as to face the cavity 10a with respect to the mold main body 121, and the mold main body 121 and the electrode 122. 123 and. Inside the electrode 122, a cooling pipe 124 through which a cooling liquid (cooling medium) flows is embedded.

The electrode 112 and the electrode 122 are arranged so as to face each other with the cavity 10a interposed therebetween. Then, in a state where the movable mold 11 is molded with respect to the fixed mold 12, the insulator 113 or the insulator 123 is sandwiched between the electrode 112 and the electrode 122.

Each of the insulator 113 and the insulator 123 is made of, for example, a silicic acid-based binder or ceramics.

The injection unit 20 includes a cylinder 21, a screw 22, an injection cylinder 23, a nozzle 24, and a cylinder heater 25. The nozzle 24 communicates with the cavity 10a of the molding die 10. The resin material supplied from the hopper (not shown) into the cylinder 21 is imparted with fluidity by the heat from the cylinder heater 25, and is injected from the nozzle 24 into the cavity 10a by the advance of the screw 22 driven by the injection cylinder 23. It is supposed to be done.

The cylinder 21 is grounded.

The high-frequency oscillation unit 30 is a unit that applies a high-frequency AC voltage between the electrodes 112 and 122, and includes a power supply 31, an oscillator 32, a matching unit 33, and feeder lines 34 and 35. In this embodiment, the frequency of the high frequency AC voltage generated in the electrodes 112 and 122 by the high frequency oscillation unit 30 is set to 27 MHz as an example.

Here, the feeding line 34 has an earth leakage shutoff valve 41 inserted in the middle of the feeding path, and the feeding line 35 has an earth leakage shutoff valve 42 inserted in the middle of the feeding path. Further, the portion of the feeder line 35 closer to the electrode 112 than the portion where the leakage cutoff valve 42 is inserted is grounded.

The control unit 60 executes drive control of the injection cylinder 23 and the cylinder heater 25, control of the high frequency oscillation unit 30, and the like. The details of the control unit 60 are not shown, but for example, the CPU and various programs executed on the CPU (basic control programs such as an OS, and various programs started on the OS to execute a specific function). It is configured to include a computer equipped with a memory such as a ROM or a RAM for storing the program and various data.

Further, the injection molding apparatus 1 is connected to the coolant circulation units (cooling medium supply device) 51 and 52 for circulating the coolant (cooling medium) with respect to the cooling pipes 114 and 124. Leakage isolation valves 43 to 46 are interposed in the coolant circulation path between the coolant circulation units 51 and 52 and the movable type 11 and the fixed type 12.

Further, the injection molding apparatus 1 includes a temperature sensor 71 for detecting the temperature of the electrode 112, a temperature sensor 72 for detecting the temperature of the electrode 122, and a temperature sensor 72 for detecting the temperature of the resin material in the cylinder 21. A temperature sensor 73 and the like are provided. While the injection molding apparatus 1 is being driven, the temperature sensors 71 to 73 sequentially transmit the detected temperature data to the control unit 60. Then, the control unit 60 that has received the temperature data feedback-controls the cylinder heater 25 and the high-frequency oscillation unit 30 using the data.

2. 2. Application of the high frequency AC voltage E to the resin material 70 introduced into the cavity 10a The application of the high frequency AC voltage E to the resin material 70 introduced into the cavity 10a will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view showing a part of the structure of the molding die 10 in an enlarged manner.

First, the resin material 70 used in the injection molding apparatus 1 according to the present embodiment is a resin material mixed with a dielectric exothermic material. Details of this will be described later.

As described above, the electrode 112 and the electrode 122 are provided so as to face the cavity 10a. Therefore, a high frequency AC voltage E is applied to the resin material 70 that is introduced into the cavity 10a and flows in the cavity 10a as shown by an arrow.

Since the resin material 70 contains a dielectric exothermic material, it receives a high frequency AC voltage E and generates heat. Therefore, the resin material 70 maintains the fluidity in the cavity 10a in a state where the high frequency AC voltage E is applied.

3. 3. Configuration of Cavity 10a The configuration of the cavity 10a provided in the molding die 10 will be described with reference to FIG. FIG. 3 is a schematic view showing the configuration of the cavity 10a provided in the molding die 10.

As shown in FIG. 3, in the injection molding apparatus 1 according to the present embodiment, the shape of the cavity 10a of the molding die 10 is, for example, two bent portions 10d between the flow base point portion 10b and the flow end point portion 10c. , 10e are provided and have a substantially U-shape in a plan view.

The resin material 70 ejected from the nozzle 24 of the injection unit 20 flows from the flow base point portion 10b to the flow end point portion 10c via the bent portions 10d and 10e.

Although detailed illustration is omitted here, in the molding die 10, the electrodes 112 and 122 are extended over the entire flow path of the resin material 70 from the flow base point portion 10b to the flow end point portion 10c. There is. That is, a high frequency AC voltage E is applied to the resin material 70 that flows through the cavity 10a of the molding die 10 from the flow base point portion 10b to the flow end point portion 10c.

4. Shapes of Electrodes 112 and 122 The shapes of the portions of the electrodes 112 and 122 facing the cavity 10a will be described with reference to FIG. FIG. 4 is a schematic cross-sectional view showing the IV-IV cross section of FIG.

As shown in FIG. 4, in the molding die 10, in a part of the extending direction (flow direction of the resin material 70) of the cavity 10a, a portion where the electrode 112 and the electrode 122 protrude toward the cavity 10a and a portion recessed are provided. It is provided.

Specifically, as shown in FIG. 4, the electrode 112 has convex portions 112a and 112b protruding toward the cavity 10a side, and concave portions recessed between the convex portions 112a and 112b. It has 112c.

Similarly, the electrode 122 has a convex portion 122c projecting convexly toward the cavity 10a side, and has concave portions 122a and 122b recessed in a concave shape. In the present embodiment, as an example, the concave portion 122a is provided at a position facing the convex portion 112a, the concave portion 122b is provided at a position facing the convex portion 112b, and the convex portion 122c is provided at a position facing the concave portion 112c. Has been done.

As shown in FIG. 4, in the molding die 10, each corner portion 112d, 112e, 112f, 112g of the convex portions 112a, 112b of the electrode 112 is formed of a curved surface. Similarly, the corner portion (tip portion) 122e of the convex portion 122c of the electrode 122 and the corner portions 122d and 122f on both sides of the concave portions 122a and 122b are formed of curved surfaces.

In the injection molding apparatus 1 according to the present embodiment, the high frequency AC voltage E is applied to the electrodes 112, 122 by forming each corner portion 112d, 112e, 112f, 112g, 122e, 122d, 122f with a curved surface as described above. At that time, it is possible to suppress the generation of tip discharge (air discharge) in the cavity 10a.

5. The application of the high frequency AC voltage E to the resin material 70 and the heat generation principle of the resin material 70 The application of the high frequency AC voltage E to the resin material 70 and the heat generation principle of the resin material 70 will be described with reference to FIG. FIG. 5 is a schematic diagram showing the heat generation principle of the resin material 70.

As shown in FIG. 5, the resin material 70 used in the injection molding apparatus 1 according to the present embodiment is a resin material in which the dielectric exothermic material 702 is mixed with the base material 701. As an example of the base material 701, a polyolefin-based resin or a polyamide-based resin thermoplastic resin can be adopted.

As an example of the dielectric exothermic material 702, a resin material having a structure in which a polyolefin-based monomer or a polyamide-based monomer and a polyether monomer are polymerized can be adopted. The detailed structure of the resin material 70 will be described later.

As shown in FIG. 5, when the high frequency AC voltage E is applied to the resin material 70 from the high frequency oscillation unit 30, the electromagnetic wave _WR propagates in the resin material 70. When the electromagnetic wave _WR propagates in the resin material 70, the mixed dielectric exothermic material 702 generates heat due to the deformation (movement) of the molecular chain due to the electromagnetic wave _WR , and the heat is transferred to the base material 701. ..

According to the above principle, the resin material 70 in the cavity 10a generates heat when a high frequency AC voltage E is applied.

6. Injection molding method An injection molding method using the injection molding apparatus 1 will be described with reference to FIGS. 6 to 8. FIG. 6 is a time chart showing the application timing of the high-frequency AC voltage and the injection pressure executed by the control unit 60 for each passage of time in injection molding using the injection molding device 1. FIG. 7 is a characteristic diagram showing the temperature and pressure of the resin material 70 in the cavity 10a at the time of injection, and FIG. 8 shows the resin material 70 at the time of holding pressure after the cavity 10a is filled with the resin material 70. It is a characteristic diagram which shows the temperature and pressure of.

As shown in FIG. 6, at the timing T1 when the power of the injection molding apparatus 1 is turned on, the control unit 60 commands the high frequency oscillation unit 30 to apply the high frequency AC voltage E1 between the electrodes 112 and 122. ..

Further, the control unit 60 commands the injection unit 20 to increase the injection pressure LP toward _P1 at the timing T1. As a result, the injection pressure LP is increased at the timing T2 so as to become the pressure _P1 .

Although not shown, the control unit 60 commands the cylinder heater 25 to be in the ON state and the resin material 70 in the cylinder 21 to be in the flow state during injection molding using the injection molding device 1. do.

Next, after the timing T2 in which the cavity 10a is filled with the resin material 70, the control unit 60 oscillates the high frequency AC voltage _E at the same predetermined value LE as between the timing T1 and the timing T2. In addition to instructing the unit 30, the injection unit 20 is instructed to apply a constant injection pressure P2 for a predetermined time until the timing T3 is reached.

The period from the timing T2 to the timing T3 shown in FIG. 6 is the holding pressure period.

Next, as shown in FIG. 7, at the time of injection from the timing T1 to the timing T2, the flow base point portion Pos1 (corresponding to the flow base point portion 10b) in the cavity 10a becomes the flow end point portion Pos2 (the flow end point portion 10c). In the entire area up to (corresponding to), the temperature _LTp of the resin material 70 is maintained at a constant temperature Tp1 having fluidity by applying a high frequency AC voltage _E having a predetermined value LE.

On the other hand, at the time of injection from the timing T1 to the timing T2, the pressure L _Pr of the resin material 70 in the cavity 10a is the pressure P3 at the flow base point portion Pos1 and gradually decreases toward the flow end point portion Pos2.

Next, as shown in FIG. 8, during the pressure holding period from the timing T2 to the timing T3, the application of the high frequency AC voltage _E at a predetermined value LE is continued for the temperature _LTp of the resin material 70 in the cavity 10a. Therefore, it is maintained at the temperature Tp1. Further, during the pressure holding period from the timing T2 to the timing T3, the pressure L _Pr of the resin material 70 in the cavity 10a is changed from the flow base point portion Pos1 to the flow end point portion Pos2 because the injection unit 20 is continuously driven. The pressure P2 is substantially constant over the entire area of the cavity 10a.

7. Heat generation amount and energy transmission by dielectric The heat generation amount and energy transmission by dielectric will be described with reference to FIGS. 9 (a) and 9 (b). 9A and 9B are schematic diagrams modeling a circuit configuration related to application of a high frequency AC voltage E in the injection molding apparatus 1, and FIG. 9B is an impedance in which the voltage between the electrodes 112 and 122 is constant. Is a characteristic diagram showing the relationship between the work cross-sectional area and the calorific value when the resin material amount 70 is flowing when the resin material amount 70 is fixed at a predetermined impedance.

First, the injection molding apparatus 1 and the injected resin material amount 70 according to the present embodiment are modeled as shown in FIG. 9A.

In the model shown in FIG. 9A, the calorific value P due to dielectric is as shown by the following equation.

P = 55.6 × (E / d) ² × f × ε _r × tanδ [W / m ³ ] ・ ・ ・ (Equation 1)
E; Voltage between electrodes [V]
d; Distance between electrodes (product wall thickness) [mm]
f; Frequency [MHz]
ε _r ; Relative permittivity tan δ; Dissipation factor From the above (Equation 1), the following three measures can be considered to increase the calorific value P.

(1) Increase the voltage E between the electrodes.

(2) Increase the frequency f.

(3) Increase the heat generation (ε _r × tan δ) of the resin material amount 70.

Regarding (1) above, air discharge is likely to occur in the cavity 10a, which is a problem. In particular, as described with reference to FIG. 4, there is concern about the occurrence of tip discharge.

Regarding (2) above, the cost of the device will increase.

Next, in the model shown in FIG. 9A, the relationship between the work cross-sectional area and the calorific value when the resin material amount 70 is flowing in the cavity 10a is as follows.

P = E ^ 2 ・ R / (R + r) ^ 2 ・ ・ ・ (number 2)
This relationship is shown in FIG. 9 (b). From the characteristic diagrams of (Equation 2) and FIG. 9 (b), "matching (transmission efficiency 100%)" is obtained when R = r.

Next, in the model shown in FIG. 9A, the work cross-sectional area S and the calorific value P have the following relationship.

P = (E ^ 2 ・ ωε _r / d) ・ S ・ ・ ・ (Equation 3)
From the characteristic diagrams of (Equation 3) and FIG. 9 (b), the calorific value P is proportional to the flow area (work cross-sectional area) S.

In consideration of the above, in the injection molding using the injection molding apparatus 1 according to the present embodiment, when the impedance value when the resin material amount 70 is filled with respect to the cavity 10a is set as a predetermined impedance value, from the initial stage of injection. The impedance value until completion is set as a predetermined impedance value.

8. Configuration of Resin Material 70 As described above, in the injection molding apparatus 1 according to the present embodiment, the resin material 70 composed of the base material 701 and the dielectric exothermic material 702 is used. The composition of the resin material 70 will be described with reference to FIG. FIG. 10 is a chemical formula of the dielectric exothermic material 702.

First, the following two types of resin materials 70 are assumed.

(1) First type <Base material 701> HIPS (impact resistant polystyrene), PP (polypropylene), LDPE (low density polyethylene), HDPE (high density polyethylene), m-PPE (modified polyphenylene ether), PMMA ( Polyolefin-based resin selected from (acrylic) <Dielectric heating material 702> In the chemical formula shown in FIG. 10, A is a polyolefin-based monomer and B is a polyether monomer. In the first type, a dielectric exothermic material 702, which is a resin material obtained by polymerizing a polyolefin-based monomer and a polyether monomer and retains cations inside the polyether portion, is adopted.

(2) Second type <Base material 701> ABS (acrylonitrile / butadiene / styrene copolymer synthetic resin), PC / ABS (polycarbonate / acrylonitrile / butadiene / styrene mixed resin), PC (polycarbonate), POM (polyacetal), Polyamide-based resin selected from PA6 (polyamide 6), PA12 (polyamide 12), and PA66 (polyamide 66) <Dielectric heating material 702> In the chemical formula shown in FIG. 10, A is a polyamide-based monomer and B is a poly. It is an ether monomer. In the second type, a dielectric exothermic material 702, which is a resin material obtained by polymerizing a polyamide-based monomer and a polyether monomer and retains cations inside the polyether portion, is adopted.

9. Heat generation of the dielectric heating material 702 by applying the high frequency AC voltage E The heat generation mechanism of the resin material 70 by applying the high frequency AC voltage E will be described with reference to FIGS. 11 (a) and 11 (b). 11A and 11B are schematic views showing a state of the dielectric exothermic material 702 immediately after the application of the high frequency AC voltage E is started, and FIG. 11B is a schematic diagram of the dielectric exothermic material 702 due to the application of the high frequency AC voltage E. It is a schematic diagram which shows the state after the cation M ⁺ has moved.

When the high frequency AC voltage E is applied to the resin material 70 including the dielectric exothermic material 702, the electromagnetic wave _WR is also propagated to the dielectric exothermic material 702 (see FIG. 5) at the position shown in FIG. 11 (a). The existing cation M ⁺ moves as shown in FIG. 11 (b).

When the cation M ⁺ moves from the position shown in FIG. 11A to the position shown in FIG. 11B, the molecular chain of the dielectric exothermic material 702 is deformed (moved). Therefore, the dielectric exothermic material 702 generates heat, and the heat is transferred to the base material 701.

The temperature of the resin material 70 used for injection molding of the injection molding apparatus 1 according to the present embodiment rises by applying a high frequency AC voltage E, and the fluidity is maintained.

10. Electromagnetic wave shielding The structure related to electromagnetic wave shielding in the molding die 10 will be described with reference to FIGS. 12 and 13. FIG. 12 is a schematic perspective view showing an external configuration of a molding die 10 in the injection molding apparatus 1, and FIG. 13 is a schematic cross-sectional view showing a cross section of XIII-XIII of FIG.

As shown in FIG. 12, the electromagnetic wave shields 81 and 82 are attached to the molding die 10 including the movable die 11 and the fixed die 12. The electromagnetic wave shields 81 and 82 are configured to extend from the molding die 10 to the lower left side in the Y direction.

As shown in FIG. 13, the electromagnetic wave shields 81 and 82 are provided so as to cover the periphery of the feeder line 34 connected to the electrode 122, and are joined so as not to form a gap between them.

Since the electrode 112 is grounded as described with reference to FIG. 1, it is not necessary to cover the feeder line 35 with an electromagnetic wave shield, but the feeder line 34 may be covered with an electromagnetic wave shield as in the case of the feeder line 34. good.

The electromagnetic wave shields 81 and 82 can be made of, for example, a copper plate or an aluminum plate (including an aluminum alloy plate).

11. Arrangement Form of Electrodes 112, 122 and Insulators 113, 123 with respect to Mold Main bodies 111, 121 The bonding form of electrodes 112, 122 with respect to mold main bodies 111, 121 will be described with reference to FIG. FIG. 14 is a schematic cross-sectional view showing an arrangement form of the electrodes 122 and the insulator 123 with respect to the mold body 121 in the fixed mold 12. Although only the fixed type 12 is shown in FIG. 14, the movable type 11 has the same configuration.

As shown in FIG. 14, the insulator 122 inserted between the mold body 121 and the electrode 122 has a size larger than that of the electrode 122 in a plan view from the Z direction. Therefore, the creepage distance (arrow in FIG. 14) between the end surface 122a of the electrode 122 and the exposed upper surface 121a of the mold body 121 is increased by the amount of the exposed upper surface 123a in addition to the end surface 123b of the insulator 123. be able to.

Further, as shown in FIG. 14, in the present embodiment, the knock pin 91 for positioning the electrode 123 with respect to the mold body 121 is made of PEEK (polyetheretherketone) resin. This also suppresses creeping discharge between the mold body 121 and the electrode 123.

Further, as shown in FIG. 14, in the fixed mold 12, a bolt 93 for fixing the electrode 123 to the mold main body 121 is fastened to the electrode 123 via a large collar 92. The color 92 is also made of PEEK resin. By adopting the large collar 92 in this way, the bolt 93 having the same potential with respect to the mold body 121 is arranged with a long creepage distance with respect to the electrode 123.

12. Configuration of Feed Lines 34, 35 The configuration of the feeder lines 34, 35 connected to the electrodes 112, 122 will be described with reference to FIG. FIG. 15 is a schematic perspective view showing the form of the feeder line 34 connected to the electrode 122. Although only the feeder line 34 is shown in FIG. 15, the feeder line 35 has the same configuration.

As shown in FIG. 15, the feeder line 34 is connected in a plane to the electrode 122 extending in the X-direction and the Y-direction. The feeder line 34 is configured by using a strip-shaped conductive member (for example, a copper plate) having a width W ₃₄ . In the present embodiment, as an example, the width W ₃₄ of the feeder line 34 is 60 to 80 mm (for example, 70 mm).

In this way, since the feeder line 34 is configured by using a band-shaped conductive member and is connected to the electrode 122 in a plane, it is possible to reduce the energy loss when the high frequency AC voltage E is applied, and the resin. The heat generation unevenness of the material 70 can be reduced.

[Modification example]
In the above embodiment, the thermoplastic resin material is adopted as an example of the resin material 70, but the present invention is not limited thereto. A thermosetting resin material may be targeted. When injecting a thermosetting resin material, a high frequency AC voltage may be applied when the resin material is cured.

Further, in the above embodiment, since the fluidity of the resin material 70 flowing in the cavity 10a is maintained by dielectric heating, one injection unit 20 is connected to the molding die 10, but the present invention. Is not limited to this. Since the temperature of the resin material flowing in the cavity can be made substantially the same in the entire cavity, even if two or more injection units are connected, hairline-like defects are unlikely to occur, and excellent appearance quality is obtained. be able to.

Further, in the above embodiment, the molding die 10 is configured by the combination of one fixed die 12 and one movable die 11, but the present invention is not limited thereto. For example, it is also possible to adopt a molding mold composed of a combination of three or more molds.

Further, in the above embodiment, the pair of electrodes 112 and 122 are provided between the flow start point portion 10b and the flow end point portion 10c of the cavity 10a in the molding die 10, but the present invention is limited thereto. is not. For example, a plurality of electrode pairs may be provided so as to be spaced apart from each other in the flow direction of the resin material in the cavity.

Further, the electrode pair may not be provided at a place where air discharge is likely to occur due to the shape of the cavity or the like.

1 Injection molding equipment 10 Molding mold 10a Cavity 10b Flow start point 10c Flow end point 10d, 10e Bent part 11 Movable type 12 Fixed type 20 Injection unit (injection machine)
30 High frequency oscillation unit (high frequency oscillation device)
34,35 Feed line 51,52 Coolant circulation unit (cooling medium supply device)
111, 121 type main body 112, 122 Electrode 113, 123 Insulator 112d, 112e, 112f, 112g, 122e, 122d, 122f Square part

Claims (9)

An injection machine that injects a resin material mixed with a dielectric exothermic material with fluidity by controlling the temperature.
A molding die having a cavity which is a flow path of the resin material and having a pair of electrodes provided in a state where each of them faces the cavity and sandwiches the resin material in a direction intersecting the direction of the flow.
A high-frequency oscillator that applies a high-frequency AC voltage to the pair of electrodes,
Equipped with
Each of the pair of electrodes is provided from the upstream end to the downstream end in the flow direction with respect to the cavity.
At least one of the pair of electrodes has a portion that projects convexly with respect to the cavity.
At least the corners of the convexly protruding portion are composed of curved surfaces.
When the impedance value of the high-frequency AC voltage applied by the high-frequency oscillating device when the entire cavity is filled with the resin material is set to a predetermined impedance value, the high-frequency oscillating device uses the resin material for the cavity. The high-frequency AC voltage with the impedance value fixed at the predetermined impedance value is applied from the initial stage of injecting to the completion of filling.
Injection molding equipment. The injection molding apparatus according to claim 1.
Each of the molding dies has a mold body and has a fixed mold and a movable mold that are fitted to each other.
One of the pair of electrodes is attached to the fixed mold body with an insulator interposed therebetween, and the other electrode of the pair of electrodes is attached to the movable mold body. On the other hand, it is attached with an insulator in between.
Injection molding equipment. The injection molding apparatus according to claim 2.
When each of the fixed type and the movable type is viewed in a plan view from the mold clamping direction of both types, the insulator has a size larger than that of the electrode.
Injection molding equipment. The injection molding apparatus according to any one of claims 1 to 3.
At least one of the pair of electrodes has a cooling passage through which a cooling medium flows.
A cooling medium supply device for supplying a cooling medium to the cooling passage is further provided.
Injection molding equipment. The injection molding apparatus according to any one of claims 1 to 4.
A control unit for controlling the injection of the resin material from the injection machine and the application of the high-frequency AC voltage by the high-frequency oscillator is further provided.
The control unit controls the injection machine so that the injection pressure is continuously applied to the cavity for a predetermined time after the resin material is filled in the entire cavity.
Injection molding equipment. The injection molding apparatus according to any one of claims 1 to 5 .
The high frequency oscillator includes an oscillator and a matching unit, and a pair of feeder lines provided for connection between the matching unit and the pair of electrodes.
At least one of the pair of feeders is configured by using a band-shaped conductive member.
Injection molding equipment. An injection step in which a resin material mixed with a dielectric exothermic material is injected with fluidity by controlling the temperature.
A flow step in which the resin material injected in the injection step is made to flow in a cavity formed in a molding mold, and a flow step.
A high-frequency AC voltage application step of applying a high-frequency AC voltage to the resin material flowing in the cavity,
Equipped with
Each of the molding dies faces the cavity, and each of the molding dies is provided from the upstream end to the downstream end in the flow direction with respect to the cavity, and the resin is provided in a direction intersecting the flow direction. It has a pair of electrodes provided with the material sandwiched between them.
At least one of the pair of electrodes has a portion that projects convexly with respect to the cavity.
At least the corners of the convexly protruding portion are composed of curved surfaces.
In the high-frequency AC voltage application step, the high-frequency AC voltage is applied between the pair of electrodes to the resin material that flows from the upstream end to the downstream end in the flow direction in the cavity.
When the impedance value of the high-frequency AC voltage applied in the high-frequency AC voltage application step when the entire cavity is filled with the resin material is set to a predetermined impedance value, the cavity is subjected to the high-frequency AC voltage application step. The high-frequency AC voltage with the impedance value fixed at the predetermined impedance value is applied from the initial stage of injecting the resin material to the completion of filling.
Injection molding method. The injection molding method according to claim 7 .
A pressure holding step is further provided in which the resin material is filled in the entire cavity in the injection step, and then the injection pressure is continuously applied to the cavity for a predetermined time.
Injection molding method. The injection molding method according to claim 8 .
After the execution of the pressure holding step, the resin material filled in the cavity is further provided with a cooling step of cooling by supplying a cooling medium to a cooling passage provided in the molding die.
Injection molding method.

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