JP6094602B2 - Injection molding apparatus and injection molding method - Google Patents

Description

  The present invention relates to an injection molding apparatus and an injection molding method, and more particularly to an injection molding apparatus and an injection molding method for injection molding a conductive material.

  Conventionally, a resin molded product is molded by an injection molding apparatus. In general, an injection molding apparatus melts pellet-shaped thermoplastic resin supplied to a hopper to a flowable temperature by heating with a heater and shearing heat due to rotation of the screw, and the screw is placed in a mold cavity that has been clamped in advance. The molten resin is advanced and filled, the filled molten resin is held by the forward force of the screw, the molded product is cooled in the cavity, and then the mold is opened to take out the molded product.

  In such an injection molding apparatus, the molten resin filled from the mold gate portion toward the end of the cavity is cooled from the surface portion that touches the cavity forming surface of the mold while moving in the cavity. As a result, the resin temperature is lowered, and as a result, the viscosity at the front end of the moving molten resin is increased and the fluidity is lowered. Therefore, if the injection pressure of the molten resin injected from the nozzle into the cavity is insufficient, there is a risk that appearance defects such as weld marks, flow marks, sink marks, and transfer defects may occur in the molded product.

  In recent years, large and thin molded products have been injection-molded to meet the needs for further weight reduction of large plastic automobile parts such as bumpers and larger and lighter frames for liquid crystal displays such as LCD TVs. Technology is required. In the case of such a large and thin molded product, if the injection pressure is insufficient, in addition to the above-mentioned appearance defects, in the conventional injection molding apparatus, there is a possibility that a short shot in which the molten resin is not filled up to the end of the cavity may occur. there were.

  On the other hand, it is conceivable to increase the injection pressure, but it is necessary to clamp the mold with a mold clamping pressure corresponding to the magnitude of the injection pressure at the time of injection molding. And a large mold capable of withstanding these injection pressures and mold clamping pressures are required. Although a method of increasing the number of gates and a method of increasing the thickness of a molded product are conceivable, there are problems such as an increase in the number of places where a weld mark may occur and an increase in material cost.

  Thus, for example, Patent Document 1 discloses so-called heat and cool molding in which heating and cooling of a mold are repeated. According to this, by heating the mold at the time of injection, the resin injected into the cavity is indirectly heated and the temperature drop of the resin is suppressed, so the injection pressure can be increased, the number of gates and the molded product Without changing the wall thickness, it is possible to suppress a decrease in fluidity of the resin.

  Also, in recent years, in order to impart conductivity necessary for electrostatic coating to a resin molded product, a conductive filler is mixed with an insulating resin as a base material, or a resin is used to improve the strength of the molded product. There is a need for a technique for injection molding a conductive material in which carbon fiber or the like is mixed with a raw material.

  As such a technique, for example, in Patent Document 2, in a nozzle of an injection molding apparatus, a conductive molten material flowing through the flow path is energized immediately before filling a cavity of a mold, and the molten material is subjected to Joule heat. A technique for generating heat directly is disclosed.

JP 2008-055894 A JP 2003-340896 A

  However, in the injection molding apparatus disclosed in Patent Document 1, a mold having a larger heat capacity than that of the molten resin to be filled is heated and its temperature is high, so that the mold is injected after the injection and pressure holding processes. Due to this cooling, the time for cooling the molded product becomes longer, and as a result, the injection molding cycle from the injection process to the removal process of the molded product may be prolonged.

  In the technique disclosed in Patent Document 2, the molten resin injected into the cavity from the nozzle is cooled by the mold while moving in the cavity as described above. Issues such as appearance defects of the molded product that may be caused by the decrease cannot be solved.

  On the other hand, when the conductive material is injection-molded, it is conceivable to heat the molten material itself filled in the cavity of the mold. According to this, since it is possible to suppress a decrease in fluidity of the conductive material in the cavity, it is possible to suppress the occurrence of appearance defects and the like of the molded product while suppressing an increase in the length of the injection molding cycle. it can.

  In the above-described method of energizing and heating the molten material itself, a plurality of conductive portions are provided for energizing the molten material filled in the mold, and a current is directly passed between the conductive portions without passing through the molten material during energization heating. In order not to flow, it is necessary that the conductive portions are electrically insulated from each other.

  However, as the number of shots of the injection molding apparatus increases, the insulation between the conductive parts gradually deteriorates, and there is a risk of leakage occurring when current flows directly between the conductive parts without passing through the molten material during energization heating. is there. As a result, the current flowing through the molten material is reduced, the current heating property of the molten material is reduced, the electric current is leaked to a device adjacent to the mold, the device is stopped by failure, the operator of the injection molding device, etc. There is a risk of electric shock.

  Therefore, the present invention suppresses the occurrence of defects in the appearance of the molded product while suppressing the lengthening of the injection molding cycle and the like when the conductive material is injection molded, and further reduces the insulation deterioration state of the mold. It is an object to provide an injection molding apparatus and an injection molding method that can be easily determined.

  In addition, this subject is a subject common also in the case of injection molding apparatuses, such as a die-casting machine which injection-molds metal materials, such as aluminum, in a shaping | molding die.

  In order to solve the above problems, the present invention is configured as follows.

First, the invention according to claim 1 of the present application is
An injection molding apparatus comprising a heating and injection means for heating and melting a conductive material to a flowable temperature and injecting it into a mold,
The mold has a plurality of conductive parts insulated from each other on at least a part of the cavity forming surface,
Energizing means for applying a predetermined voltage between the conductive parts;
Energization control means for controlling the voltage applied by the energization means,
The energization control means applies a voltage between the conductive portions by the energizing means so that the injected conductive material is energized and heated when it comes into contact with the conductive portion of the mold, and further the mold Measuring means for measuring a parameter value related to the electrical resistance between the conductive parts in a state where the conductive material is not filled with,
Have a, an insulating determining means for determining the insulation state between the conductive portion on the basis of the parameter values,
When the parameter value is greater than or equal to a first threshold, the insulation determination means determines that the insulation state is an insulation deterioration state that should be notified of a warning, and the parameter value is greater than the first threshold. When the value is equal to or greater than the second threshold value, the insulation state is determined to be an insulation deterioration state in which production of the injection molding apparatus should be stopped .

The invention according to claim 2 is the injection molding apparatus according to claim 1 ,
The conductive material is a resin material containing a conductive substance.

The invention according to claim 3 is the injection molding apparatus according to claim 1 or 2 ,
The mold is composed of a pair of molds having mold-matching surfaces that face each other when the mold is closed,
The conductive portion is provided on the cavity forming surface of each mold,
At least one of the mold matching surfaces has an insulating member that electrically insulates between the conductive portions.

The invention according to claim 4 is the injection molding apparatus according to any one of claims 1 to 3 ,
An injection control means for controlling heating and injection of the conductive material by the heating injection means;
The energization control unit controls the energization unit based on an injection state of a conductive material indicated by a control signal output from the injection control unit.

The invention according to claim 5
An injection molding method for injection molding a conductive material in a mold,
A parameter value relating to an electrical resistance between conductive parts provided on at least a part of the cavity forming surface of the mold is measured in a state where the mold is not filled with a conductive material, and the conductive property is measured based on the parameter value. An insulation measurement determination step for determining an insulation state between the parts;
A heating and injection step in which the conductive material is heated and melted to a flowable temperature and injected into the mold;
As the injected the conductive material is heated by conduction when in contact with the conductive portion, have a, energizing applying a voltage between the conductive portion,
In the insulation measurement determination step, when the parameter value is equal to or greater than a first threshold value, it is determined that the insulation state is an insulation deterioration state to be notified of a warning, and the parameter value is greater than the first threshold value. When it is equal to or greater than the second large threshold value, it is determined that the insulating state is an insulating deterioration state in which production of the injection molding apparatus should be stopped .

The invention according to claim 6 is the injection molding method according to claim 5 ,
The conductive material is a resin material containing a conductive substance.

The invention according to claim 7 is the injection molding method according to claim 5 or 6 ,
The timing of executing the energization step is controlled based on an injection state of the conductive material indicated by a control signal for controlling the injection step.

  With the above configuration, according to the invention described in claim 1 of the present application, the energization control means conducts the energization means so that the energized heating material is energized and heated when it comes into contact with the conductive portion of the mold. Since the voltage applied between the parts is controlled, the temperature of the conductive material can be controlled by this voltage control so that the temperature of the conductive material moving in the cavity does not decrease. Therefore, according to the present invention, it is possible to prevent a decrease in fluidity due to a decrease in the temperature of the conductive material and to sufficiently transmit the injection pressure to the tip of the conductive material even at a relatively low injection pressure. it can.

  As a result, it is possible to avoid appearance defects such as welds due to insufficient injection pressure. In particular, in the case of a large thin molded product, the injection molding apparatus and the mold can be downsized. In addition, since the conductive material itself is energized and heated rather than heating the mold, it is possible to suppress an increase in temperature of the mold having a large heat capacity compared to the conductive material to be filled. Therefore, the cooling time of the molded product is not lengthened, the lengthening of the injection molding cycle can be suppressed, and the running cost at the time of molding can be reduced. Furthermore, since it is not necessary to increase the thickness of the molded product in order to improve fluidity, the material cost does not increase.

  Further, according to the present invention, the parameter value relating to the electrical resistance between the conductive portions provided on at least a part of the cavity forming surface of the mold is measured in a state where the mold is not filled with the conductive material, and the parameter Since the insulation between the conductive parts is determined based on the value, the insulation deterioration state of the mold can be easily determined.

  Therefore, according to the present invention, when the conductive material is injection-molded, the occurrence of defects in the appearance of the molded product is suppressed while suppressing the prolongation of the injection molding cycle, etc. The state can be easily determined.

Also, insulation resistance determining means, if the parameter value is equal to or greater than the first threshold value, determines that the insulation state is insulative deteriorated state to be notified of the warning, the second parameter value is greater than the first threshold value If it is equal to or greater than the threshold value, it is determined that the insulation state is an insulating deterioration state in which production of the injection molding apparatus should be stopped. Based on this determination, a warning is sent to the operator or the production of the injection molding apparatus is You can stop. As a result, it is possible to more reliably prevent a molded product with insufficient current heating from being produced by continuing injection molding while the mold is insulated and deteriorated.

According to the invention described in claim 2 , when the conductive material is a resin material containing a conductive substance, for example, in order to provide conductivity necessary for electrostatic coating, an insulating property that becomes a base material Even when a conductive filler is mixed in the material or carbon fiber or the like is contained in the resin raw material in order to improve the strength of the molded product, the effect of the invention described in claim 1 can be obtained.

According to the invention of claim 3 , the molding die is composed of a pair of molds having mold-matching surfaces that come into contact with each other when the mold is closed, and the conductive portion is provided on the cavity forming surface of each mold, One mold-matching surface has an insulating member that electrically insulates between the conductive parts. Therefore, when a voltage is applied between the conductive parts, the current between the conductive parts does not flow directly between the conductive parts. The conductive material can be reliably energized.

According to the fourth aspect of the invention, the energization control unit controls the energization unit based on the injection state of the conductive material indicated by the control signal output from the injection control unit. Energization is started in accordance with the timing to be performed, and the conductive material can be efficiently energized and heated.

Further, according to the invention described in claim 5 , it is possible to achieve the same effect as the invention of the injection molding apparatus described in claim 1.

Further, according to the invention described in claim 6 , the same effect as that of the invention of the injection molding apparatus described in claim 2 can be obtained.

Further, according to the invention described in claim 7 , the same effect as that of the invention of the injection molding apparatus described in claim 4 can be obtained.

It is a figure showing roughly the whole composition of the injection molding device concerning the embodiment of the present invention. It is a partially expanded sectional view of FIG. 1 explaining the electrical heating of a conductive material. It is a graph which shows the change of the leakage current between the electroconductive parts for every shot. It is a flowchart which shows an injection molding cycle. It is a flowchart which shows the inter-type insulation check process of FIG. It is a flowchart which shows the electricity supply process of FIG. It is a time chart which shows operation | movement of an injection molding apparatus.

  Hereinafter, a first embodiment of an injection molding apparatus to which the present invention is applied will be described with reference to FIGS.

  As shown in FIG. 1, the injection molding apparatus 1 of the present embodiment includes a heat injection apparatus 2 and a mold clamping apparatus 3 disposed to face the heat injection apparatus 2. The heating injection device 2 and the mold clamping device 3 are arranged on a base frame (not shown).

  The heat injection apparatus 2 includes an injection cylinder 21, and a hopper 22 for supplying pellet-shaped thermoplastic resin, which is a raw material of a molded product, into the injection cylinder 21 is attached to the injection cylinder 21. A band heater 23 is wound around the injection cylinder 21 to heat and melt the thermoplastic resin to a flowable temperature. A screw 24 is disposed in the injection cylinder 21 so as to be rotatable and movable back and forth.

  An injection cylinder device 25 as a drive source for moving the screw 24 forward and backward is disposed behind the screw 24 (left side in FIG. 1). In the injection cylinder device 25, the injection piston 25a in the injection cylinder device 25 is moved forward or backward by hydraulic oil supplied via a pipe line (not shown).

  The rear end of the screw 24 is connected to the injection piston 25a. The screw 24 is advanced or retracted in the injection cylinder 21 by the injection piston 25a moving forward or backward in the injection cylinder device 25. . Note that a position detector (not shown) is connected to the injection piston 25a, and the screw position of the screw 24 is detected by the position detector.

  A metering motor 26 as a drive source for rotating the screw 24 is disposed behind the injection cylinder device 25. The injection cylinder 21, the screw 24, the injection cylinder device 25, and the metering motor 26 constituting the heating injection device 2 are arranged on the same axis.

  The mold clamping device 3 includes a mold device 4 including a movable mold 41 and a fixed mold 42 having mold matching surfaces that come into contact with each other when the mold is closed. The mold clamping device 3 includes a movable side mounting plate 31 to which the movable mold 41 is mounted, a fixed side mounting plate 32 to which the fixed mold 42 is mounted, and a mold clamping as a drive source for moving the movable side mounting plate 31 forward and backward. Cylinder device 33. The fixed side mounting plate 32 and the mold clamping cylinder device 33 are connected by a tie bar (not shown), and the movable side mounting plate 31 is provided so as to be capable of moving forward or backward along the tie bar.

  In the mold clamping cylinder device 33, a linearly movable mold clamping piston 33a is disposed. The mold clamping piston 33a is moved forward or backward in the mold clamping cylinder device 33 by hydraulic oil supplied into the mold clamping cylinder device 33 via a pipe line through which the working fluid flows. A movable side mounting plate 31 is connected to the front end (left end in FIG. 1) of the mold clamping piston 33a, and the mold clamping piston 33a moves forward or backward in the mold clamping cylinder device 33 to move the movable side mounting plate 31. The movable mold 41 is moved forward or backward together with the mounting plate 31. As a result, when the mold clamping piston 33a is moved forward (to the left in FIG. 1), the movable mold 41 is moved forward together with the movable side mounting plate 31, and the mold closing and clamping are performed. Further, when the mold clamping piston 33a is moved backward (moved to the right in FIG. 1), the movable mold 41 is moved back together with the movable side mounting plate 31, and the mold is opened.

  An ejector device (not shown) is disposed on the back surface (the right surface in FIG. 1) of the movable mounting plate 31. When the mold apparatus 4 is opened, the ejector apparatus is driven so that the molded product can be pushed out from the cavity and taken out. FIG. 1 shows a direct-acting type mold clamping device 3, which is a toggle method in which a toggle mechanism is provided between the mold clamping cylinder device 33 and the movable mounting plate 31. There may be.

  The mold apparatus 4 is configured such that a cavity C is formed inside by closing the space between the movable mold 41 and the fixed mold 42. In the movable mold 41 and the fixed mold 42, flow paths F for flowing a cooling liquid such as cooling water are formed.

  Furthermore, the injection molding apparatus 1 of the present embodiment has a cooling device 5 for cooling the mold device 4. The cooling device 5 includes a cooling pump 51, and the cooling pump 51 is connected to the movable mold 41 and the fixed mold 42 via a coolant supply pipe 52 and a discharge pipe 53, respectively. Each supply pipe 52 and discharge pipe 53 is provided with a shutoff valve 54 that shuts off the flow of the coolant. According to this cooling device 5, by driving the cooling pump 51 with all the shut-off valves 54 open, the coolant is circulated through the flow paths F of the movable mold 41 and the fixed mold 42, and the movable mold The mold 41 and the fixed mold 42 are cooled. An individual cooling pump 51 may be provided in order to cool the movable mold 41 and the fixed mold 42 individually.

  So far, the conventionally known configuration of the injection molding apparatus 1 has been described. Next, the configuration of the injection molding apparatus 1 that is characteristic of the present invention will be described.

  As shown in FIG. 1, the movable mold 41 and the fixed mold 42 of the present embodiment have a nested structure. In other words, the movable mold 41 includes a mold outer portion 43 and a conductive portion 47 provided inside the mold outer portion 43 via the insulating member 45. Similarly, the fixed mold 42 includes a die outer shape portion 44 and a conductive portion 48 provided inside the die outer shape portion 44 via an insulating member 46. The conductive portions 47 and 48 are provided on the cavity forming surfaces of the movable mold 41 and the fixed mold 42.

  The insulating member 46 is made of, for example, alumina, zirconia, silicon nitride, silicon carbide, polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), polyphenylene sulfide (PPS), quartz, titanium oxide, polyether ether ketone (PEEK). ), Polyimide, polyamideimide and the like. The insulating member 46 can be provided between the mold outer portions 42 and 43 and the conductive portions 47 and 48 by a method such as coating, thermal spraying, spraying, transferring, fitting, in-mold molding, and bonding. The insulating member 46 may be provided with an insulating layer made of resin or ceramics exemplified on the surface of the metal member. Further, the insulating member 46 can be selected based on desired pressure resistance performance (maximum applied voltage by the energization device 61), operating temperature (maximum temperature of the mold device 4), and the like.

  An insulating member 49 that electrically insulates between the conductive portions 47 and 48 is provided on the mold matching surface of the movable mold 41. In the case of the present embodiment, the insulating member 49 is provided in a layered manner so as to cover the portion formed by the conductive portion 47 in the mold matching surface of the movable mold 41. The insulating member 49 only needs to be provided on at least one of the mold mating surface of the movable mold 41 and the mold mating surface 42 a of the fixed mold 42.

  In addition, the injection molding apparatus 1 includes an energization device 6 for applying a voltage between the conductive portions 47 and 48 of the mold device 4. In the case of the present embodiment, the energization device 6 is a DC power source that can apply a constant voltage. The energization device 6 may be an AC power source.

  The heating injection device 2 is provided with a resistance sensor 62 for detecting the electric resistance value of the conductive material P melted by the band heater 23 in the injection cylinder 21. The sensor signal output from the resistance sensor 62 is configured to be input to an energization control unit 140 described later.

  An in-mold resistance value sensor 63 for detecting an electric resistance value between the conductive portions 47 and 48 is connected to the conductive portions 47 and 48 of the mold apparatus 4. In this embodiment, the in-mold resistance sensor 63 flows from the conductive portion 48 of the mold apparatus 4 to the conductive portion 47 through the insulating layer 29 in a state before the cavity C is filled with the conductive material P. A current sensor capable of detecting the leakage current is provided.

  The control unit 100 is a mold clamping control that controls the band heater 23 of the heating injection device 2, the heating cylinder device 25 and the heating motor control unit 110 that controls the metering motor 26, and the mold clamping cylinder device 33 of the mold clamping device 3. Unit 120, a cooling control unit 130 that controls the cooling pump 51 and each shutoff valve 54 of the cooling device 5, and an energization control unit 140 that controls the energization device 61 of the energization device 6. In the present embodiment, the energization control unit 140 performs on / off control of a predetermined voltage output from the energization device 6, but may be capable of controlling a voltage value output from the energization device 6.

  Here, the conductive material P used as a raw material for injection molding is obtained by mixing a conductive filler with a base material of an insulating thermoplastic resin according to desired characteristics. The thermoplastic resin is at least one selected from, for example, polypropylene, polyamide, polysulfene sulfide, polyimide, polyether ketone, polyether ether ketone, ABS, ASA, and polycarbonate. The conductive filler is at least one selected from metal-based conductive agents such as metal fibers, metal powders, and metal flakes, and carbon-based conductive agents such as carbon fibers, carbon composite fibers, carbon black, and graphite. It is. The conductive material P may be a metal material itself. The metal material is at least one selected from, for example, non-ferrous metals such as zinc, aluminum, and magnesium and alloys thereof.

  Next, the principle of energization heating of the conductive material P will be described with reference to FIG. In FIG. 2 and the like, the symbol PL indicates a parting line in which the mold mating surfaces of the movable mold 41 and the fixed mold 42 in the mold apparatus 4 are in contact with each other.

  As shown in FIG. 2, the conductive material P injected and filled into the cavity C from a nozzle (not shown) moves in the cavity C toward its end (upward in FIG. 2) It cools from the surface part which touched the cavity formation surface. However, when a voltage is applied between the conductive portions 47 and 48 so that the conductive portion 48 is at a higher potential than the conductive portion 47, the conductive material P is applied to the conductive material P from the conductive portion 48 side in the thickness direction of the cavity C. A current flows toward the conductive portion 47 (see the waveform arrow on the right side of FIG. 2). By this energization, the conductive material P generates Joule heat due to its own electrical resistance, that is, energized and heated. Therefore, the conductive material P is filled up to the end of the cavity C in a state in which a decrease in fluidity due to the increase in viscosity at the tip of the moving conductive material P is suppressed while maintaining the resin temperature. .

  At this time, since the conductive portions 47 and 48 are insulated from each other by the insulating member 49 on the mold matching surface, no current flows directly from the conductive portion 48 to the conductive portion 47.

  Next, the leakage current in the insulating member 49 between the conductive portions 47 and 48 will be described with reference to FIG.

  As described above, as the number of shots of the injection molding apparatus 1 increases, the insulating member 49 for insulating between the conductive portions 47 and 48 to which a voltage is applied in order to energize and heat the conductive material P, for example, Aging deteriorates due to wear, use temperature, use pressure, energization voltage, ultraviolet rays, etc., and its insulation performance gradually decreases. As shown in FIG. 3, the leakage current flowing between the conductive portions 47 and 48 via the insulating member 49 during energization heating gradually increases as the insulation performance decreases.

  Further, the insulation performance of the insulating member 49 may suddenly deteriorate due to sudden events such as dents, scratches, deformation, overheating, overpressure, and overvoltage, which is difficult to predict in advance. . Therefore, in order to monitor the insulation performance of the insulating member 49, it is desirable to measure the current peak value of the leakage current of the insulating member 49 for each shot.

  In the energization control unit 140 described later, normal values I1, warning values I2, and danger values I3 set in advance as thresholds for determining the insulation state of the insulating member 49 are stored in a built-in memory or the like. The current peak value of the leakage current of the insulating member 49 of the new mold apparatus 4 is set as the normal value I1. When the measured current peak value of the leakage current is larger than the normal value I1 and not more than the warning value I2 at a certain number of shots, it is determined that the production of the molded product by the injection molding apparatus 1 can be continued. When the current peak value is larger than the warning value I2 and not more than the dangerous value I3, it is determined that it is necessary to warn the operator of the injection molding apparatus 1. If the current peak value is greater than or equal to the critical value I3, it is determined that production should be stopped.

  Next, regarding the flow of the control operation of the injection molding apparatus 1 controlled by the control unit 100, the flowcharts of FIGS. 4 to 6 and the screw position, injection pressure, energization ON / OFF, and ON / OFF of the cooling pump therebetween. This will be described with reference to the time chart of FIG.

  First, at time t 0, the mold clamping cylinder device 33 is driven based on the mold clamping signal output from the mold clamping control unit 120 to move the movable mold 41 toward the fixed mold 42, and the mold device 4. Is closed and clamped (step S1). The mold clamping pressure at this time is set to a high pressure that does not open the mold apparatus 4 during injection. Further, based on the mold clamping signal, the cooling control unit 130 stops driving the cooling pump 51 (switches from ON to OFF).

  Next, as will be described in detail later, an inter-mold insulation check of the mold apparatus 4 is performed (step S2).

  Next, at time t1, the heating and injection control unit 110 outputs an injection signal, and the screw 24 is moved forward (moved to the right in the drawing) by the injection cylinder device 25 of the heating and injection device 2 at a preset injection speed. Injection filling of the molten conductive material P into the cavity C of the mold apparatus 4 is started (step S3).

  In addition, at time t1, the energization control unit 140 controls the energization device 61 based on the injection signal to apply a predetermined voltage between the conductive units 47 and 48, so that the conductive material P filled in the cavity C is applied to the conductive material P. Conducting heating is performed (step S4).

  Next, at time t2 when the screw 24 moves forward to the screw position A1 where the conductive material P is completely filled in the cavity C, the heating / injection control unit 110 outputs a holding pressure signal, and heating is performed based on the holding pressure signal. The injection device 2 is controlled, and the holding pressure P2 that is lower than the maximum pressure P1 at the time of injection filling is applied to the conductive material P filled in the mold device 4 until a preset holding time elapses. (Step S5).

  Next, at time t3 when the pressure holding time has elapsed and the screw position of the screw 24 has advanced to A2, the molded product is cooled for a preset cooling time. At the same time, in the heating and injection apparatus 2, for the next shot, the conductive material P is heated and melted to a flowable temperature by the band heater 23, and the screw 24 is rotated by the metering motor 26 and retracted to a predetermined position. At this time, the raw material supplied from the hopper 22 is heated and melted in the injection cylinder 21, and is stored in front of the screw 24 as the screw 24 moves backward (step S6).

  Next, at time t4 when the cooling time has elapsed, the mold clamping control unit 120 controls the mold clamping device 3, and the mold clamping piston 33a of the mold clamping cylinder device 33 is moved backward to open the mold device 4. Perform (step S7).

  Next, the molded product is ejected from the cavity C of the mold device 4 by the ejector device (step S8).

  Finally, it is determined whether or not molding has been completed. If it is determined that molding has been completed, the injection molding cycle is terminated (step S9).

  Here, the inter-mold insulation check process, which is a subroutine of step S2, will be described with reference to FIG.

  First, based on the current peak value of the leakage current flowing between the conductive parts 47 and 48 measured by the in-mold resistance value sensor 63, it is determined whether or not the current peak value is smaller than a preset danger value I3. (Step S11).

  If NO in step S11, that is, if it is determined that the current peak value is greater than or equal to the dangerous value I3, the production of the molded product by the injection molding apparatus 1 is stopped (step S12). In addition, after production is stopped, it may be replaced with a new mold device 4 to resume production.

  If YES in step S11, that is, if it is determined that the current peak value is smaller than the dangerous value I3, it is determined whether or not the current peak value is smaller than a preset warning value I2 (step S13).

  If NO in step S13, that is, if it is determined that the current peak value is greater than or equal to the warning value I2, for example, an alarm sound is generated by a buzzer (not shown) provided in the injection molding apparatus 1, or a warning light (not shown). Is turned on and blinked to warn the operator of the injection molding apparatus 1 (step S14), and the process returns to the main routine of FIG.

  If YES in step S13, that is, if it is determined that the current peak value is smaller than the warning value I2, the process returns to the main routine of FIG.

  As described above, the insulation between the movable mold 41 and the fixed mold 42 can be checked by the subroutine.

  Further, the energization process as a subroutine of step S4 will be described with reference to FIG.

  First, it is determined whether or not an injection signal output from the heating / injection control unit 110 to the heating / filling device 2 is ON (step S21).

  If it determines with YES (an injection signal is ON) in step S21, the electricity supply control part 140 will start electricity supply to the electricity supply apparatus 61 (step S22).

  At this time, the energization control unit 140 controls the voltage applied between the conductive units 47 and 48 by the energization device 61 so that the temperature of the conductive material P moving in the cavity C does not decrease and the fluidity does not decrease. To do. In the present embodiment, a preset constant voltage is applied between the conductive portions 47 and 48 by the energization device 61.

  Next, it is determined whether or not the holding pressure signal output from the heating injection control unit 110 to the heating filling device 2 is ON (step S23).

  If it is determined in step S23 that YES (the holding pressure signal is ON), the energization of the energization device 61 is terminated and the process returns to the main routine of FIG. 4 (step S24).

  As described above, the energization device 61 can be controlled by the subroutine based on the injection state of the conductive material P indicated by the control signal output from the heating injection control unit 110.

  As described above, according to the present embodiment, the energization control unit 140 energizes and heats the energization device 61 so that the injected conductive material P is energized and heated when it contacts the conductive portions 47 and 48 of the mold device 4. Controls the voltage applied between the conductive portions 47 and 48, and therefore, by this voltage control, the temperature of the conductive material P moving in the cavity C can be controlled so as not to decrease. Therefore, according to the present invention, a decrease in fluidity due to a temperature decrease of the conductive material P can be prevented, and the injection pressure can be sufficiently transmitted to the tip of the conductive material P.

  As a result, since the conductive material P melted at a relatively low injection pressure can be filled in the cavity C, it is possible to avoid occurrence of appearance defects such as short shots due to insufficient injection pressure. In the case of a large thin molded product, the injection molding apparatus 1 and the mold apparatus 4 can be downsized. In addition, since the conductive material P itself is energized and heated, the cooling time of the mold apparatus 4 is not lengthened. Therefore, the injection molding cycle can be shortened, and the running cost at the time of molding can be reduced. Furthermore, since it is not necessary to increase the thickness of the molded product in order to improve fluidity, the material cost does not increase.

  Furthermore, according to the present embodiment, the electrical resistance between the conductive portions 47 and 48 provided on at least a part of the cavity forming surface of the mold apparatus 4 in a state where the mold apparatus 4 is not filled with the conductive material P. Since the parameter value is measured and the insulation between the conductive portions 47 and 48 is determined based on the parameter value, the insulation deterioration state of the mold apparatus 4 can be easily determined.

  Therefore, according to the present embodiment, when the conductive material P is injection-molded, the occurrence of appearance defects or the like of the molded product is suppressed while suppressing the lengthening of the injection molding cycle, and the mold device 4 It is possible to easily determine the insulation deterioration state.

  Further, according to the present embodiment, when the leakage current between the conductive parts 47 and 48 is the warning value I2 or more, it is determined that the insulation state is an insulating deterioration state that should be notified of the warning, and the leakage current is a dangerous value. If it is equal to or greater than I3, it is determined that the insulation state is an insulating deterioration state in which the production of the injection molding apparatus 1 should be stopped. Based on this determination, a warning is sent to the operator or the production of the injection molding apparatus 1 is Can be stopped. As a result, it is possible to more reliably prevent a molded product with insufficient current heating from being produced by continuing the injection molding while the mold apparatus 4 is deteriorated in insulation.

  Further, according to the present embodiment, when the conductive material P is a resin material containing a conductive material, for example, in order to impart conductivity necessary for electrostatic coating, the conductive material P is electrically conductive to the insulating material as a base material. The present invention can also be applied to the case where carbon fiber or the like is mixed with a resin raw material in order to mix a functional filler or to improve the strength of a molded product.

  In addition, according to the present embodiment, the mold apparatus 4 includes the movable mold 41 and the fixed mold 42 that have mold-matching surfaces that come into contact with each other when the mold is closed. , 42 is provided on the cavity forming surface, and at least one die-matching surface has an insulating member 49 that electrically insulates between the conductive portions 47, 48, so that a voltage is applied between the conductive portions 47, 48. The conductive material P between the conductive portions 47 and 48 can be reliably energized without causing a current to flow directly between the conductive portions 47 and 48.

  Moreover, according to this embodiment, since the electricity supply control part 140 controls the electricity supply apparatus 61 based on the injection | emission state of the conductive material P which the control signal output from the heating injection control part 110 shows, the electroconductive material P Energization can be started in accordance with the timing at which is injected, and the conductive material P can be efficiently energized and heated.

  The present invention is not limited to the illustrated embodiments, and various improvements and design changes can be made without departing from the spirit of the present invention.

  For example, in the present embodiment, a resin material is injection-molded as a conductive material, but is not limited to this, and may be a molten material that is conductive at least during heating. For example, a metal material such as aluminum It may be a die casting machine for injection molding.

  In the present embodiment, the heat injection device 2 and the mold clamping device 3 use a hydraulic actuator as a drive source. However, the present invention is not limited to this, and an electric actuator may be used.

  Further, in the present embodiment, the mold apparatus 4 is cooled by circulating the coolant with the cooling pump 51. However, the present invention is not limited to this, and the mold apparatus 4 is naturally not provided with a cooling means. The mold apparatus 4 may be cooled by radiating heat or using a cooling means such as a Peltier element.

  As described above, according to the present invention, when the conductive material is injection-molded, it is possible to suppress the occurrence of defects in the appearance of the molded product while suppressing the lengthening of the injection molding cycle and the like. Since it is possible to easily determine the insulation deterioration state, there is a possibility of being suitably used in the field of manufacturing technologies such as an injection molding apparatus or an automobile or a liquid crystal display that uses the injection molding apparatus for manufacturing various parts.

DESCRIPTION OF SYMBOLS 1 Injection molding apparatus 2 Heating injection apparatus (heating injection means)
4 Mold device (molding tool)
47, 48 Conducting part 49 Insulating member 61 Energizing device (energizing means)
63 In-mold resistance sensor (measuring means)
110 Heating injection control unit (injection control means)
140 Energization control unit (energization control means)
C Cavity P Conductive material

Claims (7)

An injection molding apparatus comprising a heating and injection means for heating and melting a conductive material to a flowable temperature and injecting it into a mold,
The mold has a plurality of conductive parts insulated from each other on at least a part of the cavity forming surface,
Energizing means for applying a predetermined voltage between the conductive parts;
Energization control means for controlling the voltage applied by the energization means,
The energization control means applies a voltage between the conductive portions by the energizing means so that the injected conductive material is energized and heated when it comes into contact with the conductive portion of the mold, and further the mold Measuring means for measuring a parameter value related to the electrical resistance between the conductive parts in a state where the conductive material is not filled with,
Have a, an insulating determining means for determining the insulation state between the conductive portion on the basis of the parameter values,
When the parameter value is greater than or equal to a first threshold, the insulation determination means determines that the insulation state is an insulation deterioration state that should be notified of a warning, and the parameter value is greater than the first threshold. The injection molding device, wherein if it is equal to or greater than a second threshold value, the insulation state is determined to be an insulation deterioration state in which the production of the injection molding device should be stopped . The injection molding apparatus according to claim 1, wherein the conductive material is a resin material containing a conductive substance. The mold is composed of a pair of molds having mold-matching surfaces that face each other when the mold is closed,
The conductive portion is provided on the cavity forming surface of each mold,
At least one of the mold mating surface, an injection molding apparatus according to claim 1 or claim 2, characterized in that an insulating member for electrically insulating the said conductive part. An injection control means for controlling heating and injection of the conductive material by the heating injection means;
Said energization control means, any one of claims 1 to 3, characterized by controlling said energizing means based on the exit status of conductive material control signal indicates output from the injection control means The injection molding apparatus described in 1. An injection molding method for injection molding a conductive material in a mold,
A parameter value relating to an electrical resistance between conductive parts provided on at least a part of the cavity forming surface of the mold is measured in a state where the mold is not filled with a conductive material, and the conductive property is measured based on the parameter value. An insulation measurement determination step for determining an insulation state between the parts;
A heating and injection step in which the conductive material is heated and melted to a flowable temperature and injected into the mold;
As the injected the conductive material is heated by conduction when in contact with the conductive portion, have a, energizing applying a voltage between the conductive portion,
In the insulation measurement determination step, when the parameter value is equal to or greater than a first threshold value, it is determined that the insulation state is an insulation deterioration state to be notified of a warning, and the parameter value is greater than the first threshold value. The injection molding method , wherein if it is greater than or equal to a second large threshold value, the insulation state is determined to be an insulation deterioration state in which production of the injection molding apparatus should be stopped . The injection molding method according to claim 5 , wherein the conductive material is a resin material containing a conductive substance. The injection molding method according to claim 5 or 6 , wherein the timing of executing the energization step is controlled based on an injection state of a conductive material indicated by a control signal for controlling the injection step.

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