JP2013226810A - Resin molding manufacturing method using electromagnetic induction heating type mold apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably shorten the time to be required, in a continuous resin molding manufacturing cycle using an electromagnetic induction type mold.SOLUTION: Induction heating is started simultaneously with or as soon as possible after mold opening, not after removal of a resin molding. The target temperature of the induction heating is temporarily kept at a temperature (T1) so as not to cause an operation failure when a mold is closed, and temperature is raised to a resin filling temperature (T2) after the resin molding is removed and the mold is closed. The process is repeated at least once.

Description

  The present invention relates to a method for producing a resin molded body using an electromagnetic induction heating type mold apparatus used for resin molding.

  Examples of the resin molding method using a mold include an injection molding method, a compression molding method, and a blow molding method. These are methods in which after a raw material resin is put into a mold, heat is transferred and the resin is shaped and solidified.

  As a method for heating the mold, a method using high-frequency electromagnetic induction heating is known in addition to a method using an electric heater (Patent Document 1). This high-frequency electromagnetic induction heating method employs a method of heating a mold by high-frequency electromagnetic induction heating, and can be rapidly heated.

  Further, in Patent Document 2, a heating medium is provided by providing a medium passage in the mold for performing induction heating at least after opening the mold and before completion of resin filling, and for circulating a refrigerant liquid for cooling after heating. There has been proposed a method of reducing the time required for production per one while maintaining the quality of the resin molding by cooling later and supplying compressed air to the medium passage after cooling.

Japanese Patent Laid-Open No. 08-039571 JP 60-96427 A

  However, in the method described in Patent Document 2, when rapid heating is performed from mold opening to filling completion, if it takes time to take out the product, induction heating proceeds excessively during that time, and the mold expands too much, and the molding machine Since the continuous molding is stopped by the mold protecting function, the time required for the production becomes rather long.

  Therefore, an object of the present invention is to stably reduce the time required in a continuous resin molding manufacturing cycle using an electromagnetic induction heating mold.

First, as a first invention for injection molding, the following steps (a) to (e) are sequentially performed, and then the steps (a) to (e) are repeated to solve the above-described problems.
(A) After receiving the mold closing completion signal or the mold closing confirmation signal, induction heating to a temperature T2 suitable for molding the resin material to be used is started.
(B) After reaching the temperature T2, filling of the resin is started.
(C) After the completion of filling, the induction heating is stopped, and a cooling fluid is supplied to the medium passage to start cooling.
(D) After cooling, along with the start of mold opening, compressed air is supplied to the medium passage to start the removal of the cooling fluid, and induction heating to a temperature T1 within a range in which the mold can be closed is started.
(E) The resin molded body is taken out and mold closing is started.
(However, T2> T1.)

  That is, the feature of the first invention resides in that the cooling of the resin molded body is finished, the heating is started immediately after the mold opening is started, and the heating is performed in two stages. If induction heating was started after taking out the resin molded body, the mold was cooled in the meantime and it took too much time, but in the conventional method of starting induction heating with the mold filling temperature as the target, The problem was that the mold would not expand due to heating during the removal operation and would not close. In order to solve this, even if heating is started as soon as possible after mold opening or after mold opening, the target heating temperature is once set at a temperature (T1) at which no malfunction occurs when the mold is closed. The control was performed so that the temperature was raised to the resin filling temperature (T2) upon receipt of the mold closing completion signal or the mold closing confirmation signal. Accordingly, the temperature can be increased during opening and closing to shorten the time, and the temperature can be further increased when there is no problem in closing the mold. Further, when the mold opening is started, compressed air is supplied to the medium passage through which the cooling fluid passes to eliminate the cooling fluid, whereby the first temperature increase can be appropriately advanced.

In addition, as a second invention for blow molding or press molding, the following steps (a ′) to (e) are sequentially performed, and then the steps (a ′) to (e) are repeated to solve the above problems. It is.
(A ′) Induction heating to a temperature T2 ′ that is suitable for molding of the resin material to be used and can be closed is started, and a parison or a resin sheet is inserted between the molds.
(B ′) Close the mold and supply air from the air inlet to deform the parison or deform the resin sheet.
(C) After the deformation is completed, the induction heating is stopped, and a cooling fluid is supplied to the medium passage to start cooling.
(D) After cooling, along with the start of mold opening, compressed air is supplied to the medium passage to start the removal of the cooling fluid, and induction heating to a temperature T1 within a range in which the mold can be closed is started.
(E) The resin molded body is taken out and mold closing is started.
(However, T2 ′> T1.)

  That is, the feature of the second invention is that the cooling of the resin molded body is finished and the heating is started immediately after the mold opening is started. If induction heating is started after taking out the resin molded body, the mold is cooled until then, and it takes too much time. In order to solve this, heating is started as soon as possible after mold opening or after mold opening, and the temperature is increased in parallel with the take-out operation, to the temperature T2 ′ necessary for the next parison or resin sheet deformation. The time taken to raise the temperature can be greatly shortened. Further, when the mold opening is started, compressed air is supplied to the medium passage through which the cooling fluid passes to eliminate the cooling fluid, whereby the first temperature increase can be appropriately advanced. A parison is used for blow molding, and a resin sheet is used for press molding.

  In either of the first and second inventions, the gist of the invention is as follows. It has been common knowledge that heating is started in a state where the mold is open because it is likely to cause deformation and breakage of the mold in the production of a conventional resin molded body. However, as long as the thermal deformation that can be closed without deforming the mold is within a range that can be suppressed, heating can be advanced to the limit by the idea of reversal that heating can proceed even in an open state. Is a feature of the present invention. Although high accuracy is required for the control for this purpose, since it is an electromagnetic induction heating type, overshoot hardly occurs and heating within the above range is sufficiently possible.

  Furthermore, according to the present invention, the following steps can be added or subdivided, so that it can be suitably carried out according to the resin molding.

By performing the next step (f) after filling of the step (b) or after the start of deformation of the step (b ′) and before cooling of the step (c), adjustment of resin crystallization, The quality can be improved by promoting penetration into the cavity.
(F) Induction heating to a temperature T3 which is a heat retention temperature for adjusting the quality of the obtained molded body during filling or deformation of the resin, or at the pressure keeping step after filling or deformation, and keeping the heat for an arbitrary time To do.
(However, T3 ≧ T2 and T3 ≧ T2 ′.)

In addition, as the cooling of the step (c), at least the next step (c1) and the step (c2) are sequentially performed to adjust the cooling rate and the cooling time, and the progress of crystallization and the surface of the resin are adjusted. Encourage preparation and improve quality.
(C1) A first cooling mechanism for supplying a refrigerant liquid as the cooling fluid to the medium passage is executed to cool to the temperature T4.
(C2) The first cooling mechanism is used to cool to a temperature T5 at which the shape of the molded product is stable.
(However, T3>T4> T5 and T1> T5.)

Further, by performing the next step (c3) after the step (c1) and before the step (c2), further progress of crystallization and surface preparation can be performed.
(C3) The temperature is kept at the temperature T4 for an arbitrary time.

  In the steps (c1) and (c2), another cooling mechanism can be used. In addition to the first cooling mechanism, the heating induction coil is formed by winding a copper tube into a coil shape. You may use the 2nd cooling mechanism which supplies a refrigerant | coolant liquid in it. In that case, in the step (d), the compressed air is also supplied into the copper pipe and the elimination of the refrigerant liquid is started, so that appropriate cooling in a low temperature range can be easily promoted and used at that time. Subsequent induction heating can be rapidly advanced by quickly removing the refrigerant liquid.

  Other cooling mechanisms that can be used in the above steps (c1) and (c2) are the holding portion of the induction coil for heating, and the surface opposite to the cavity surface of the metal portion constituting the cavity surface. A third cooling mechanism that blows and cools compressed air on the anti-cavity surface or both can be used. In particular, a gap is necessary between the holding portion of the heating induction coil and the anti-cavity surface, but this can be realized by utilizing the gap for cooling.

  Whichever cooling mechanism is combined in addition to the essential requirements, the degree of freedom for adjusting and improving product quality is improved by increasing the selectivity of the cooling mechanism. Moreover, if the cooling mechanism is used at the same time, the cooling efficiency can be improved and the required time can be shortened.

  Further, as another step for improving the quality, after reaching the temperature T2 or T2 ′ in the step (a) or (a ′), the resin filling in the step (b) or the step (b ′) is performed. Before starting the deformation of the resin, by performing the step (g) of holding the heat generated by the heating induction coil over the entire cavity surface for an arbitrary time, the heating unevenness of the cavity surface is eliminated. The quality of the resin molding can be improved and stabilized.

  The present invention can be used for injection molding, blow molding, or press molding, and regardless of which of the heating induction coil and the medium passage is closer to the cavity surface, that is, the shape of the mold and the type of molding. Regardless of this, a resin molded body can be produced stably and rapidly.

Longitudinal sectional view showing a first example of an electromagnetic induction heating mold apparatus for resin injection molding capable of carrying out the present invention The graph which shows the example of transition of the mold temperature change at the time of implementing this invention by injection molding Longitudinal sectional view showing a second example of an electromagnetic induction heating mold apparatus for resin injection molding capable of implementing the present invention Longitudinal sectional view showing a first example of an electromagnetic induction heating mold apparatus for resin blow molding capable of implementing the present invention Longitudinal sectional view showing a second example of an electromagnetic induction heating mold apparatus for resin blow molding capable of implementing the present invention The graph which shows the example of transition of the die temperature change at the time of implementing this invention by blow molding or press molding A longitudinal sectional view showing a first example of an electromagnetic induction heating mold apparatus for resin press molding capable of carrying out the present invention Longitudinal sectional view showing a second example of an electromagnetic induction heating mold apparatus for resin press molding capable of carrying out the present invention

  An electromagnetic induction heating mold apparatus for resin molding embodying the present invention is an apparatus having a resin molding mold (hereinafter simply referred to as “mold”). Hereinafter, each of the injection mold (FIGS. 1 and 3), the blow mold (FIGS. 4 and 5), and the press mold (FIGS. 7 and 8) will be described.

  First, the resin molding die shown in FIG. 1 used as an injection molding die will be described. As shown in FIG. 1, the mold 11 is separated into two molds, a fixed mold 11a and a movable mold 11b, and the two molds 11a and 11b are used by abutting the surfaces facing each other.

  Cavity surfaces 12a and 12b are formed on the surfaces of the two molds 11a and 11b facing each other, and the cavity 12 is formed between the two molds 11a and 11b by the two molds 11a and 11b abutting each other. Is done. The one mold 11a is formed with a nozzle hole 13a from the outer surface toward the cavity surface 12a. In the case of injection molding, the nozzle hole 13 can supply molding resin to the cavity 12 through the runner gate 13b.

  Of these two molds 11a and 11b, the portions having the cavity surfaces 12a and 12b are respectively formed by magnetic metal portions 14a on which magnetic metals are arranged. An induction coil made of an insulating resin that holds the induction coil 15a on the outer surface of the magnetic metal portion 14a, that is, the surface of the magnetic metal portion 14a opposite to the surface on which the cavity surfaces 12a and 12b are formed. A holding unit 15 is arranged. A plurality of induction coils 15 a are arranged in the induction coil holding portion 15.

  When the induction coil 15a is energized, the magnetic metal portion 14a is heated, and the cavity surface 12a can be efficiently heated. In addition, the induction coil 15a may be provided not only on the fixed mold 11a as shown in FIG. 1 but also on the movable mold 11b, or on both the fixed mold 11a and the movable mold 11b. When the movable mold 11b is provided, the magnetic metal portion 14b is heated, and the cavity surface 12b side can be efficiently heated.

  Examples of the magnetic metal include metals having a relative permeability of 200 or less, and metals of 150 or less are preferable. The relative permeability may be higher than 200, but since there are few such metals and they are not economical, a metal of 150 or less is sufficient. Specific examples of the metal that satisfies such conditions include iron materials, general steel materials such as SUS430 and SUS410. The relative permeability may be larger than 1.

  Since the induction coil holding part 15 is formed of a heat insulating insulating material made of resin, it is possible to prevent heat from escaping from the magnetic metal part 14a through the induction coil holding part 15, and to increase the temperature of the magnetic metal part 14a. Can be done faster.

  Examples of the heat insulating insulating resin forming the induction coil holding portion 15 include phenol and epoxy resin.

  As shown in FIG. 1, the induction coil holding portion 15 is formed by sandwiching the induction coil 15a with resin, forming a gap 15c therebetween, and having an air introduction path 15b to the gap 15c. If it is, it can be suitably used as a third cooling mechanism described later, but the form is not limited to this, and it may be impregnated between the coils constituting the induction coil 15a. .

  The induction coil 15a is obtained by winding a metal wire or a metal tube in a coil shape, and generates a magnetic field by passing an electric current therethrough. As the metal constituting the induction coil 15a, a metal having a low electrical resistivity is preferable, and examples thereof include silver and copper.

  The number of induction coils 15a provided in the induction coil holding unit 15 can be appropriately provided according to the size of the two molds 11a and 11b, the cavity, the type of resin used, and the like.

  In this induction coil, ferrite may be arranged on a part or all of one surface or both surfaces selected from the outer surface and the outer peripheral surface. By arranging this ferrite, it is possible to absorb a magnetic field deviating from the flow of magnetic flux generated from the induction coil, to promote heating of the magnetic metal portion 14a, and to reduce noise leakage to peripheral devices. it can.

  Since the induction coil holding portion 15 is made of resin, when the diagonal center of the cavity is used as a reference, the induction coil arranged on the outermost side can be easily arranged in the outermost induction coil installation range, Generation of burrs in the molded product can be suppressed, and volatile gas from the molten resin can be easily discharged out of the cavity. More specifically, the outermost induction coil installation range A is preferably within a range from the outer peripheral edge of the cavity 12 to the inside of 30 mm, and preferably within a range of 5 mm.

  In the induction coil holding part 15, the outside of the tube induction coil 15 a is sandwiched by the resin forming the induction coil holding part 15 and has a gap 15 c around it, and the inside of the induction coil 15 a is also The resin is not filled and is in a hollow state.

The plurality of induction coils 15a are energized by an energizing device (not shown), but the energizing device may be one or two or more energizing devices. When one energization device is used, the same amount of current can be simultaneously supplied to each induction coil 15a, and heating can be made uniform. On the other hand, when two or more energization devices are used, the energization timing and the amount of current can be adjusted for each energization device, and heating can be changed intentionally for each portion. When it is desired to change the heating for each part of the mold, it is preferable to use at least two energizing devices.
When two or more energization devices are used, the maximum number of energization devices is the number of induction coils 15a.

  The outer periphery of the core part of the mold composed of the magnetic metal parts 14a and 14b and the induction coil holding part 15 is covered with the heat insulating materials 16a and 16b to prevent heat from escaping to the outside. And the outer periphery of the heat insulating materials 16a and 16b is covered with a mother die 17.

  Examples of the heat insulating materials 16a and 16b include phenol and fluororesin.

  A through hole 18 constituting a medium passage for water cooling is formed in a portion made of the magnetic metal, that is, the magnetic metal portion 14a. The number of the through holes 18 can be set to an arbitrary number in accordance with the degree of cooling of the magnetic metal portion 14a.

  The mold is cooled after the molding, but as a cooling means, a method using the first cooling mechanism using the through hole 18, a second cooling mechanism using the inside of the induction coil 15 a, and the induction coil are used. A method using a third cooling mechanism that cools by introducing compressed air around 15a or the like can be given.

  First, the first cooling mechanism is a mechanism that allows cooling water to pass through the above-described through-hole 18, and thereby the magnetic metal portion 14 a can be cooled. At this time, it is preferable to provide an air purge mechanism for passing air through the through-hole 18 and drying the through-hole 18. If this air purge mechanism is provided, the water in the through hole 18 can be discharged to the outside by the air purge mechanism after passing the cooling water. When the mold is reheated, the water in the through hole 18 is bumped. Or heating unevenness of the magnetic metal portion 14a can be prevented.

  Next, the second cooling mechanism is a mechanism in which a copper tube is wound as a coil as the induction coil 15a, and cooling water or air is passed through the copper tube. The induction coil 15a is cooled, This is a method of indirectly cooling the surrounding at the base point.

  The third cooling mechanism uses a coil of copper wire or copper tube wound as the induction coil 15a, and a gap 15c is partially provided between the induction coil holding portion 15 and the induction coil 15a. 15c is a mechanism that allows air to pass through the air introduction path 15b, in which the induction coil 15a is cooled and the surroundings are indirectly cooled based on this. The gap 15c passes through the induction coil holding portion 15 in the example of FIG. 1, but is in contact with the surface of the magnetic metal portion 14a that is in contact with the induction coil holding portion 15, that is, the anticavity surface, and the anticavity surface. May be air-cooled. The cooling of the magnetic metal portion 14a is faster when the anti-cavity surface is air-cooled.

  These second cooling mechanism and third cooling mechanism mainly cool the induction coil 15a that has been induction-heated, and the surrounding cooling also proceeds by the transfer of cold heat therefrom. As a preferable aspect of cooling the mold, it is conceivable to use the first cooling mechanism and use either one or both of the second cooling mechanism and the third cooling mechanism. Thereby, the magnetic metal part 14a and the induction coil 15a can be cooled together.

  Examples of the thermoplastic resin used in the present invention include polyamide (nylon 6, nylon 66, etc.), polyolefin (polyethylene, polypropylene, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), polycarbonate, polyamideimide, polyoxymethylene, polyphenylene oxide. Polysulfone, polyethersulfone, polyetheretherketone, polyetherimide, polystyrene, ABS, polyphenylene sulfide, liquid crystal polyester, a copolymer of acrylonitrile and styrene, and the like can be used.

  Next, a continuous manufacturing method by injection molding of a resin molded body using the electromagnetic induction heating mold apparatus for resin molding shown in FIG. 1 will be described. FIG. 2 shows the change in temperature through the series of resin molding steps.

  First, at the initial time, the fixed mold 11a and the movable mold 11b of the injection mold 11 are either opened or closed. Since the resin cannot be filled unless it is closed, first the mold closing is started, that is, the operation of closing the mold 11 is started by abutting the two molds 11a and 11b. At the same time, it is desirable that the induction coil 15a is energized to start heating the magnetic metal part 14a of the fixed mold 11a and the movable mold 11b, and the temperature is raised to the temperature T1 before the mold is closed. This temperature T1 is a high temperature state in a range in which expansion due to heating of the molds 11a and 11b can close the molds. That is, it is the upper limit that can be heated before the mold is completely closed.

  In the temperature transition diagram of FIG. 2, it is assumed that the temperature has been opened in advance and is cooled below the temperature T1, but if the mold is closed from the beginning, the temperature T1 is promptly considered without being considered. Heating to the next temperature T2 may be performed. However, in that case, it is desirable that the control unit receives the mold closing confirmation signal that can confirm that the mold is closed.

Next, process (a) is demonstrated.
If the mold is closed from the beginning, the mold closing is completed if the mold closing operation is performed as in the above step (X) after the control section receives the mold closing confirmation signal. After the control unit receives a mold closing completion signal for confirming the above, the temperature rise to a temperature exceeding the temperature T1 is started. The mold closing completion signal and the mold closing confirmation signal may be the same in the system. The temperature T2 that is the target of the ultimate heating temperature is a temperature at which the resin necessary for injection molding is sufficiently softened. Naturally, T2> T1. This temperature T2 is appropriately selected between the melting point, glass transition temperature, or crystallization temperature of the resin used and a temperature higher by 50 ° C. than the melting point, glass transition temperature, or crystallization temperature, but is not limited thereto. It is not something. A more preferred upper limit is a temperature 20 ° C. higher than the melting point, glass transition temperature, or crystallization temperature. As said resin, if it is a thermoplastic resin, it will not be limited to the kind.

  When step (a) is completed, that is, when the temperature measured as that of the cavity surface reaches the temperature T2, the process may proceed to the next step (b) immediately. However, even if the temperature is actually measured on the cavity surface, the temperature of the entire cavity surface may not reach that level. In this case, depending on the shape and type of the mold, the step (g) of maintaining the temperature T2 for a period of time until the cavity surface sufficiently reaches the temperature T2 and the temperature unevenness is negligible. It is good to put between (b). The heat retention time in this step (g) is obtained by an empirical rule or is calculated by simulation.

  Next, the step (b) will be described. When the temperature T2 is reached, or when the temperature T2 is maintained for an arbitrary time thereafter, filling of the resin material is started. Specifically, the cavity 12 is filled with resin through the nozzle hole 13a and the runner gate 13b. After filling the resin material in this step (b), a pressure holding (holding pressure) step is performed.

  After the start of filling in this step (b) and during the pressure-holding step, the temperature T2 may be maintained, but induction heating is performed to a temperature T3 that is a heat-retaining temperature for adjusting the quality of the obtained resin molded body. It may be convenient in terms of quality if the step (f) of holding for an arbitrary time necessary for the adjustment of the above is performed. That is, T3 ≧ T2. Here, the adjustment of the quality includes promotion of crystallization of the resin molded body to be produced, change in surface state, and the like. In the case of the mold shown in FIG. 1, the holding time is preferably 5 seconds to 60 seconds from the viewpoint of warping deformation due to shrinkage of the resin molding.

  After completion of injection in the step (b) or after completion of heat retention in the step (f), induction heating is stopped, a cooling fluid is poured into the medium passage serving as the first cooling mechanism, and cooling is started ( c) is started. In general, as described above, water is used as a coolant liquid that is a cooling fluid, and water cooling is performed by passing water through the through holes 18. In this step (c), not only the first cooling mechanism but also the second cooling mechanism and the third cooling mechanism may be used in combination.

  Specifically, the cooling may be performed in two stages of the following steps (c1) and (c2). That is, cooling to temperature T4 is first performed as a step (c1), and then cooling to temperature T5 is performed as a step (c2). Here, T3 ≧ T2> T4> T5 and T1> T5. Here, the cooling mechanism used in step (c1) and step (c2) may be the same, or the cooling mechanism used in step (c1) and step (c2) may be switched. For example, it is possible to switch in such a manner that only the third cooling mechanism is used in the step (c1) and all the cooling mechanisms are used in the step (c2). After cooling to temperature T4 in this step (c1), the temperature may be kept at temperature T4 for an arbitrary time as step (c3). Depending on the nature of the resin and the resin molded body to be produced, the resin molded body is held for an appropriate period of time in order to promote crystallization of the resin or to adjust the surface state of the resin molded body. It is good to change. Moreover, since the state of the resin molding obtained also changes with the cooling rate of a process (c1) and a process (c2), the 1st thru | or 3rd cooling mechanism is selected and the speed of the cooling fluid is selected with each cooling mechanism. Adjust as appropriate.

  The temperature T5 that is the cooling target at the end of the step (c) needs to be a temperature at which the obtained resin molded body is not deformed. Therefore, the temperature T5 is not a value depending on the mold, but a value depending on the type of resin used in the resin molded body. After cooling to this temperature T5, the following process (d) is started. First, the control unit issues a mold opening start signal to start mold opening. In parallel with this, compressed air is introduced in order to remove the cooling fluid (a refrigerant liquid and mainly water) remaining in the medium passage of the first cooling mechanism. In parallel with this, induction heating targeting the temperature T1 is started. This is because if the refrigerant liquid is not removed, the required time becomes longer due to the extra heat capacity required for heating during the next resin molding. However, the mold opening start signal, the introduction of compressed air, and the start of induction heating do not have to be started completely at the same time, but may be started in parallel without waiting for completion of each. It may be mixed within a range that does not significantly affect the time. However, a smaller time lag is desirable. Therefore, in the case of a system in which all the processes are automated, when the completion of cooling to the temperature T5 is confirmed by the sensor, the control unit uses it as a trigger to transmit a mold opening start signal to start the introduction of compressed air. When induction heating is started, the production can proceed efficiently.

  While removing the refrigerant liquid and induction heating as described above, when the mold is opened until the resin molded body can be taken out, the step (e) of starting the mold closing after taking out the resin molded body is performed. That is, since the resin molded body itself is released from the holding pressure with the start of mold opening, even if the temperature becomes higher than the temperature T5 in a range where the resin molded body does not deform, it does not immediately deform. Moreover, since the temperature increase target at this stage is the temperature T1 at which the molds 11a and 11b can be closed without any problem, the temperature difference is not so large. For this reason, even if heating is started, the influence on the quality of the resin molded body is almost negligible. On the other hand, if the induction heating is started after completing the removal, the mold is cooled to less than T5 until the removal is completed, and an extra time is required for raising the temperature to the temperature T2 necessary for the next resin filling. And power will be applied. For this reason, by starting the temperature increase to the temperature T1 at the start of mold opening, it is possible to prevent the cooling to an unnecessarily low temperature and to manufacture a single resin molded body for the first time. Time can be significantly reduced. Note that the start of mold closing in this step (e) does not have to wait for the temperature T1 to reach, and it is desirable to start mold closing promptly after the resin molded body is taken out. This is because if the mold is closed, the step (a) of raising the temperature to the next temperature T2 can be started quickly.

  And if a control part receives a mold closing completion signal, said process (a) will be started. That is, the temperature rise to the temperature T2 is started. Thereafter, by repeating steps (a) to (e), a resin molded body can be produced in a shorter time cycle than in the past.

  The above description of the process has been made by taking the injection mold shown in FIG. 1 as an example, but the present invention does not depend on the shape of the mold or the type of molding. For example, the present invention can be implemented without any problem even if the injection mold 11X as shown in FIG. 3 is used as the injection mold. This is different from FIG. 1 in that the positional relationship between the magnetic metal portion 14a and the induction coil holding portion 15 is reversed. The cavity surface 12c forming the cavity is formed of the surface of the induction coil holding portion 15, and the through hole 18 serving as the first cooling mechanism is slightly separated from the cavity surface 12c, so that the cooling tends to be slightly slower than the embodiment of FIG. However, it is not an absolute one. When the temperature T5 is reached, mold opening is started, compressed air is introduced, induction heating is started (step (e)), and the mold is closed at the temperature T1. The manufacturing cycle can be shortened in the same manner by taking the timing of waiting for the temperature T2 and starting the temperature rise to the temperature T2 (step (a)).

  In addition, the present invention can be practiced without problems even with an injection mold having other components such as a heating mechanism and a cooling mechanism.

  Furthermore, the present invention can be practiced without problems even if the molding method changes. For example, blow molding using a blow molding die as shown in FIGS. 4 and 5 is also possible. First, after explaining the exemplified blow mold, the difference from the case of using the injection mold will be described.

  The blow molding die 21 shown in FIG. 4 will be described. The two molds 21a and 21b are separated into two molds, and the two molds 21a and 21b face each other and face each other.

  Cavity surfaces 22a and 22b are formed on the surfaces of the two molds 21a and 21b facing each other, and the cavity 22 is formed between the two molds 21a and 21b by abutting the two molds 21a and 21b. Is done.

  Of these two molds 21a and 21b, the portions having the cavity surfaces 22a and 22b are respectively formed by magnetic metal portions 24a on which magnetic metals are arranged. An induction made of insulating resin that holds a plurality of induction coils 25a on the outer surface of the magnetic metal portion 24a, that is, the surface of the magnetic metal portion 24a opposite to the surface on which the cavity surfaces 22a and 22b are formed. A coil holding part 25 is arranged. As the heat insulating insulating resin forming the induction coil holding part 25, the same resin as the resin forming the induction coil holding part 15 can be used.

  As the magnetic metal constituting the magnetic metal portion 24a, the same metal as the magnetic metal constituting the magnetic metal portion 14a can be used.

  As shown in FIG. 4, the induction coil holding portion 25 has an induction coil 25a sandwiched between the resins as shown in FIG. 4, and a gap 25c is formed between them. The induction coil holding portion 25 has an air introduction path 25b to the gap 25c. If it is, it can be used suitably as said 3rd cooling mechanism, However, A form is not limited to this, The thing of the state impregnated between the coils which comprise the induction coil 25a may be used.

  The induction coil 25a can be the same as the induction coil 15a. That is, the inner side of the induction coil 25a may be one that can be used as the second cooling mechanism using a hollow copper tube that is not filled with resin. The number of induction coils 25a provided in the induction coil holding part 25 can be appropriately provided according to the size of the two molds 21a and 21b, the cavity, the type of resin used, and the like.

  The outer periphery of the core part of the mold composed of the magnetic metal part 24a and the induction coil holding part 25 is covered with heat insulating materials 26a and 26b to prevent heat from escaping to the outside. And the outer periphery of the heat insulating materials 26 a and 26 b is covered with a mother die 27. As the heat insulating materials 26a and 26b, the same materials as the heat insulating materials 16a and 16b are used.

  A water-cooling through hole 28 serving as a medium passage of the first cooling mechanism is formed in the magnetic metal portion, that is, the magnetic metal portion 24a. An arbitrary number of the through holes 28 can be provided in accordance with the degree of cooling of the magnetic metal portion 24a.

  After the molding, the mold is cooled, but as a cooling means, a method using the first cooling mechanism using the through hole 28, a second cooling mechanism using the induction coil 25a, and a first using the gap 25c. 3 A method using a cooling mechanism can be given. These three types of cooling mechanisms are the same cooling mechanisms as the three types of cooling mechanisms used in the above-described injection mold 11.

  Further, the blow molding die 21X shown in FIG. 5 is opposite to the blow molding die 21 shown in FIG. 4 in that the positions of the magnetic metal portion 24a and the induction coil holding portion 25 are reversed, and the cavity surfaces 22c and 22d. Is formed on the surface of the induction coil holding part 25. Since the through hole 28 is separated from the cavity surfaces 22c and 22d, the cooling rate is slightly lower than that of the blow molding die shown in FIG. 4, but the basic configuration is the same.

  The procedure for carrying out the method for producing a resin molded body according to the present invention using the blow molding mold shown in FIG. 4 or FIG. 5 is different from the case of using the injection molding mold of FIG. The explanation is centered. The transition of the temperature is shown in FIG.

  As an initial state, since it is necessary to put a parison (the previous stage of 23 in the figure), it is necessary to open the mold. If the mold is open from the beginning, induction heating to the temperature T1 is started as it is, and if the mold is closed, a mold opening start signal is sent from the control unit to start the mold opening and the temperature T1 Induction heating to start. In the induction heating to the temperature T1, the induction coil 25a is energized to heat the magnetic metal parts of the two molds 21a and 21b.

  Regardless of whether the start is as described above, the step (a ′) of performing induction heating to a temperature T2 suitable for molding the resin material used as the step (a) is performed. During this step (a '), the above-mentioned parison (the previous stage of 23 in the figure) is extruded from a die (not shown) and inserted between the molds. Note that the temperature T2 ′ is equal to or higher than the melting point, the glass transition temperature, or the crystallization temperature of the resin to be used, similar to the temperature T2, and is based on any of the melting point, the glass transition temperature, and the crystallization temperature. The temperature is appropriately selected at a temperature not higher than 50 ° C., preferably selected as appropriate at a temperature not higher than 20 ° C., and is suitable for molding a resin, but at a temperature within a range where the mold can be closed without any problem. It is necessary to be. For this reason, if the temperature T2 'is reached by the completion of the insertion of the parison, the temperature is maintained during that time (step (g)). Further, even when the insertion of the parison is completed before the temperature T2 ′ is reached, this step (g) is performed in order to keep the entire cavity surfaces 22a and 22b (or 22c and 22d) warm uniformly. You may keep warm.

  After the parison has been inserted, the mold is closed, and air is supplied from the air inlet to deform the parison. After reaching the temperature T2 ′, the cavity surfaces 22a, 22b (or 22c, 22d) are formed together. The blow molded body 23 is formed by tightly deforming the cavity 22.

  At this time, instead of maintaining the temperature T2 ′, a step (f) of inductively heating to a higher temperature T3 and keeping the temperature may be performed in order to prepare resin crystallization or finish the surface appropriately. . That is, T3 ≧ T2 ′, and preferably T3> T2 ′. This is the same as in the case of the above injection molding. Subsequent steps (c) and (d) are also the same as in the case of the injection molding. That is, using the first cooling mechanism and other cooling mechanisms, cooling is performed while holding the heat retention at the temperature T4 as necessary. Although the positional relationship of the cooling mechanism is different between the blow molding dies shown in FIGS. 4 and 5, the present invention can be carried out in the same manner in the order of heat retention and cooling only in the case where the cooling rate is different. When the cooling is completed, the mold starts to open and the temperature rise by induction heating is started. As a result, it is possible to manufacture with a shorter time than the conventional manufacturing method.

  In the next step (e ′), unlike the step (e), only the resin molded body is taken out. Thereafter, the process returns to step (a '), and induction heating to the temperature T2' is started.

  Still another molding method for carrying out the present invention is press molding. For example, press molding using a press molding die as shown in FIGS. 7 and 8 can also be performed. First, after explaining the illustrated press-molding mold, differences from the case where a blow-molding mold is mainly used will be described.

  The press-molding die 31 shown in FIG. 7 will be described. The mold 31 is separated into two molds, a male mold 31a and a female mold 31b, and the two molds 31a and 31b are used by abutting the surfaces facing each other.

  Cavity surfaces 32a and 32b are formed on the surfaces of the male mold 31a and the female mold 31b that face each other, and the male mold 31a and the female mold 31b face each other, whereby the cavity 32 is interposed between the two molds 31a and 31b. Is formed.

  Of these male mold 31a and female mold 31b, the portions having the cavity surfaces 32a and 32b are respectively formed by magnetic metal portions 34a on which magnetic metals are arranged. The induction coil made of an insulating resin that holds the induction coil 35a on the outer surface of the magnetic metal portion 34a, that is, the surface of the magnetic metal portion 34a opposite to the surface on which the cavity surfaces 32a and 32b are formed. A holding unit 35 is disposed.

  As the magnetic metal constituting the magnetic metal portion 34a, the same metal as the magnetic metal constituting the magnetic metal portion 14a can be used.

An induction coil holding portion 35 made of a heat insulating insulating material made of resin is formed in contact with the surface of the magnetic metal portion 34a opposite to the cavity surfaces 32a and 32b. A plurality of induction coils 35 a are arranged in the induction coil holding part 35.

  As the heat insulating insulating resin forming the induction coil holding part 35, the same resin as the resin forming the induction coil holding part 15 can be used.

  As shown in FIG. 7, the induction coil holding portion 35 is formed by sandwiching the induction coil 35a with a resin, forming a gap 35c therebetween, and having an air introduction path 35b to the gap 35c. If it is, it can be used suitably as said 3rd cooling mechanism, However, A form is not limited to this, The thing of the state impregnated between the coils which comprise the induction coil 35a may be used.

  The induction coil 35a can be the same as the induction coil 15a. Further, the number of induction coils 35a provided in the induction coil holding part 35 can be appropriately provided in accordance with the two molds 31a and 31b, the size of the cavity, the type of resin used, and the like.

  The outer periphery of the core part of the mold composed of the magnetic metal part 34a and the induction coil holding part 35 is covered with heat insulating materials 36a and 36b to prevent heat from escaping to the outside. And the outer periphery of the heat insulating materials 36 a and 36 b is covered with a mother die 37. As said heat insulating materials 36a and 36b, the material similar to said heat insulating materials 16a and 16b is used.

  A through-hole 38 for water cooling is formed in a portion made of the magnetic metal, that is, the magnetic metal portion 34a. An arbitrary number of the through holes 38 can be provided in accordance with the degree of cooling of the magnetic metal portion 34a.

  After the molding, the mold is cooled. As a cooling means, a method using the first cooling mechanism using the through hole 38, a second cooling mechanism using the induction coil 35a, and the induction coil 35a are used. A method using a third cooling mechanism that introduces air through the air introduction path 35b into the gap 35c provided in the periphery can be given. As these three types of cooling mechanisms, the same cooling mechanisms as the three types of cooling mechanisms used in the above-described injection mold 11 can be used.

  Further, the press-molding die 31X shown in FIG. 8 differs from the press-molding die 31 shown in FIG. 7 in that the positions of the magnetic metal portion 34a and the induction coil holding portion 35 are reversed, and the cavity surfaces 32c and 32d. Is formed on the surface of the induction coil holding portion 35. Since the through hole 38 is separated from the cavity surfaces 32c and 32d, the cooling rate is slightly lower than that of the press mold shown in FIG. 7, but the basic configuration is the same.

  The procedure for carrying out the method for producing a resin molded body according to the present invention using the press molding die shown in FIG. 7 or FIG. 8 is different from the case of using the blow molding die of FIG. The explanation will be focused on. The temperature transition diagram here uses the same FIG. 6 as that used in the above blow molding die.

  Since it is necessary to put a resin sheet (not shown) to be pressed as an initial state, it is necessary to open the mold. If the mold is open, induction heating to the temperature T1 is started as it is. If the mold is closed, a mold opening start signal is sent from the control unit to start the mold opening and to the temperature T1. Induction heating is started. In the induction heating to the temperature T1, the induction coil 35a is energized to heat the magnetic metal parts of the two molds 31a and 31b. These are the same as in the case of blow molding.

  Regardless of whether the start is as described above, the step (a ′) of performing induction heating to a temperature T2 ′ suitable for molding the resin material used as the step (a) is performed. During this step (a ′), a resin sheet (not shown) is inserted between the female mold 31 b and the male mold 31 a to be formed. The temperature T2 ′ is the same as the value at the time of the above blow molding, and is a temperature suitable for resin molding like the temperature T2, but at the same time it should be within a range where the mold can be closed without any problem. It is. For this reason, if the temperature T2 'is reached by the completion of the insertion of the resin sheet, the temperature is maintained during that time (step (g)). Further, even when the insertion of the resin sheet is completed prior to reaching the temperature T2 ′, this step (g) is performed in order to warm the entire cavity surfaces 32a and 32b (or 32c and 32d) without unevenness. You may keep warm.

  After the completion of the step (a ′), that is, before and after the turn, after reaching the temperature T2 ′ and inserting the resin sheet, as the step (b ′), the mold is closed, and the male die 31a and The resin sheet is deformed by being sandwiched between the female mold 31b, and is closely deformed into the cavity 32 formed by combining the cavity surfaces 32a and 32b (or 32c and 32d) to form a press-molded body.

  Subsequent steps are the same as in the case of blow molding. If necessary, heat is maintained at T3 (f), cooling to T4 (c1), if necessary, heat retaining (c3), cooling to T5 (c2). When the cooling is completed, the mold starts to open and the temperature rise by induction heating is started (d). As a result, it is possible to manufacture with a shorter time than the conventional manufacturing method. After taking out the resin molding (e ′), the process returns to step (a ′), and induction heating to the temperature T2 ′ is started.

11, 11X Injection mold 11a Fixed mold 11b Movable mold 12 Cavity 12a, 12b, 12c Cavity surface 13, 13a Nozzle hole 13b Runner gate 14a, 14b Magnetic metal part 15 Induction coil holding part 15a Induction coil 15b Air introduction path 15c Clearances 16a and 16b Heat insulating material 17 Master 18 Through hole

21 Blow molding dies 21a, 21b Mold 22 Cavities 22a, 22b, 22c Cavity surface 23 Blow molding 24a Magnetic metal part 25 Induction coil holding part 25a Induction coil 25b Air introduction path 25c Gap 26, 26a, 26b Heat insulation 27 Mother Mold 28 Through hole

31 Press molding die 31a Male die 31b Female die 32 Cavity 32a, 32b Cavity surface 34a Magnetic metal part 35 Induction coil holding part 35a Induction coil 35b Air introduction path 35c Clearance 36, 36a, 36b Insulation material 37 Base 38 Through hole

Claims (8)

The two molds constituting the resin molding mold form a cavity surface made of a highly magnetic metal part on the surfaces facing each other,
In a place where heat can be transferred to the cavity surface, the heating induction coil and a medium passage serving as a passage for cooling fluid are provided.
Using an electromagnetic induction heating mold apparatus for resin molding, which has a control unit that can open and close the two molds by a command by an electric signal, and can acquire that the opening and closing is completed by an electric signal,
A method for continuously producing a resin molded body, wherein at least the following steps (a) to (e) are sequentially performed, and thereafter (a) to (e) are repeated one or more times.
(A) After receiving the mold closing completion signal or the mold closing confirmation signal, induction heating to a temperature T2 suitable for molding the resin material to be used is started.
(B) After reaching the temperature T2, filling of the resin material is started.
(C) After the completion of filling, the induction heating is stopped, and a cooling fluid is supplied to the medium passage to start cooling.
(D) After cooling, along with the start of mold opening, compressed air is supplied to the medium passage to start the removal of the cooling fluid, and induction heating to a temperature T1 within a range in which the mold can be closed is started.
(E) The resin molded body is taken out and mold closing is started.
(However, T2> T1.) The two molds constituting the resin molding mold form a cavity surface made of a highly magnetic metal part on the surfaces facing each other,
In a place where heat can be transferred to the cavity surface, the heating induction coil and a medium passage serving as a passage for cooling fluid are provided.
Blow molding electromagnetic induction heating mold apparatus or press molding electromagnetic induction having a control unit capable of opening and closing the two molds by a command by an electrical signal and obtaining an electrical signal that the opening and closing has been completed Using a heating mold device,
A method for continuously producing a resin molded body, wherein at least the following steps (a ′) to (e) are sequentially performed, and then (a ′) to (e) are repeated one or more times.
(A ′) Induction heating to a temperature T2 ′ that is suitable for molding of the resin material to be used and can be closed is started, and a parison or a resin sheet is inserted between the molds.
(B ′) Close the mold and supply air from the air inlet to deform the parison or deform the resin sheet.
(C) After the deformation is completed, the induction heating is stopped, and a cooling fluid is supplied to the medium passage to start cooling.
(D) After cooling, along with the start of mold opening, compressed air is supplied to the medium passage to start the removal of the cooling fluid, and induction heating to a temperature T1 within a range in which the mold can be closed is started.
(E ′) The resin molded body is taken out.
(However, T2 ′> T1.) The resin molded product according to claim 1 or 2, wherein the next step (f) is performed after the filling of the step (b) or the start of deformation of the step (b ') and before the cooling of the step (c). Continuous manufacturing method.
(F) Induction heating to a temperature T3 which is a heat retention temperature for adjusting the quality of the obtained molded body during filling or deformation of the resin, or at the pressure keeping step after filling or deformation, and keeping the heat for an arbitrary time To do.
(However, T3 ≧ T2 and T3 ≧ T2 ′.) The continuous manufacturing method of the resin molding in any one of Claims 1 thru | or 3 with which cooling of the said process (c) implements at least following process (c1) and process (c2) in order.
(C1) A first cooling mechanism for supplying a refrigerant liquid as the cooling fluid to the medium passage is executed to cool to the temperature T4.
(C2) The first cooling mechanism is used to cool to a temperature T5 at which the shape of the molded product is stable.
(However, T3>T4> T5 and T1> T5.) The heating induction coil is a copper tube wound in a coil shape,
In addition to the first cooling mechanism as a cooling mechanism used in the step (c1), the step (c2), or both, a second cooling mechanism for supplying a refrigerant liquid into the copper pipe is included.
In the step (d), the compressed air is also supplied into the copper pipe to start removing the refrigerant liquid.
The continuous manufacturing method of the resin molding of Claim 4.   In addition to the first cooling mechanism as the cooling mechanism used in the step (c1), the step (c2), or both, the holding part of the induction coil for heating, the anti-cavity surface of the metal part constituting the cavity surface, or The continuous manufacturing method of the resin molding of Claim 4 or 5 including the 3rd cooling mechanism which sprays and compresses compressed air to both of them. The continuous manufacturing method of the resin molding in any one of Claim 4 thru | or 6 which performs the following process (c3) after the said process (c1) and before the said process (c2).
(C3) The temperature is kept at the temperature T4 for an arbitrary time. After reaching the temperature T2 or T2 ′ in the step (a) or (a ′), before starting the resin filling or deformation in the step (b) or (b ′), the next step (g) is performed. The continuous manufacturing method of the resin molding in any one of Claim 1 thru | or 7 performed.
(G) Keeping the temperature for an arbitrary time while maintaining the temperature T2 or T2 ′.

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