JP5277401B2 - Mold heating method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for heating a mold which is improved so as to uniformly heat the entire area of cavity surface without unevenness of temperature on the basis of an induction heating method which heats a mold by using a transverse type induction heating coil, and an apparatus therefor. <P>SOLUTION: In the method for heating a mold in which a transverse type induction heating coil 4 is interposed between mold register surfaces of a fixed mold 2 and a movable mold 3 of a mold 1 and a cavity surface of the mold 1 is heated by applying a high frequency current supplied from a high-frequency power source 6 to the coil, during energizing the induction heating coil, a reciprocating movement in a plane direction of the mold is added to the induction heating coil to induction-heat the mold. Specificallly, a coil drive device 7 is provided to the induction heating coil 4 and the induction heating coil 4 reciprocates in a plane direction of the mold 1 by using the coil drive device. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a die heating method and a heating apparatus for preheating a die to a required temperature by applying an induction heating method for an aluminum die-cast casting die.

  As is well known, in the die casting method, the mold is preheated prior to the injection of the molten metal in order to ensure the meltability of the molten metal injected into the mold. Conventionally, as a heating method of this mold, a method of heating the mold with a burner or energizing an electric heater embedded in the mold and heating it to a required temperature has been used. Since it is necessary to heat the whole, and the time required for preheating the mold becomes longer, a mold heating method using induction heating has been proposed as an alternative method (for example, Patent Document 1, Patent) Reference 2).

  The induction heating method for heating a mold is a transverse type heating coil (a flat inductor in which a coil conductor is wound in a spiral shape) between a fixed type and a movable type having a split structure and facing a mold-matching surface. ) Is inserted and a high frequency current is supplied to the heating coil from a high frequency power source to induce an eddy current in the mold, and the mold is heated by the eddy current. A high frequency current is passed through the coil. Thus, the cavity surface area of the mold can be rapidly heated to the preheating temperature in a short time by the skin effect of induction heating.

JP 2000-218356 A JP 2008-97948 A

  By the way, when the mold is preheated to a predetermined temperature prior to pouring the molten metal by die casting as described above, the entire cavity surface of the mold is also used to cast a good die cast. It is important to heat as uniformly as possible without uneven temperature.

  In this regard, it has been found that the transverse induction heating coil having a structure in which the coil conductor is wound spirally as described above has little heat generation in the central portion of the coil. Although the higher the heating efficiency, the smaller the distance between them, the distribution of the induced current induced in the mold is not uniform due to the shape of the coil conductor, the winding pitch, and the like. For this reason, when the transverse type coil interposed between the molds is supplied with power held in a fixed position as in Patent Documents 1 and 2, the surface area of the mold facing the central part of the coil is not localized. As a result, a part with a small induced current is generated, resulting in a problem that the entire cavity surface of the mold is not heated uniformly.

  In addition, when a transverse type induction heating coil is used in a fixed position between the molds, the dedicated induction heating coil is prepared for each mold to be used. It is necessary to prepare.

  In order to solve the above problems, the object of the present invention is based on an induction heating method in which a mold is heated using a transverse type induction heating coil, and the entire cavity surface of the mold is uniformly distributed without temperature unevenness. An object of the present invention is to provide a mold heating method improved so that it can be heated and a heating apparatus used for carrying out the heating method.

In order to solve the above-described problems, according to the present invention, a transverse induction heating coil is disposed on a die-matching surface of a mold having a split structure, and a high-frequency current is passed through the coil to mold the mold. In the heating method of the mold in which the cavity surface is heated,
In the first solution, while the induction heating coil is energized, the mold is induction-heated while moving the coil over the entire cavity surface of the mold (claim 1).

  Further, in the second solution means, in parallel with induction heating by energization of the induction heating coil, the mold is heated by spraying water vapor onto the cavity surface of the mold (claim 2), and its specific mode As a coil conductor of the induction heating coil as a pipe conductor, a large number of nozzle holes are dispersed and perforated on the peripheral surface, and water vapor supplied from the outside to the pipe conductor is blown to the cavity surface of the mold through the nozzle holes ( Claim 3).

  On the other hand, as a heating device for carrying out the first heating method described above, according to the present invention, a transverse type induction heating coil interposed on the mating surface of the mold is provided over the entire cavity surface of the mold. A drive means for moving is provided (claim 4).

  In addition, a heating apparatus for carrying out the second heating method described above is provided for a transverse type induction heating coil composed of a pipe conductor in which a large number of nozzle holes are dispersed and perforated on the peripheral surface, and water vapor is supplied to the coil. A water vapor generating device to be supplied is provided.

  Moreover, the steam uses superheated steam of 100 ° C. or higher (claim 6).

  By adopting the above-described mold heating method and heating device, the following effects can be obtained.

  First, with respect to the transverse induction heating coil interposed between the molds, induction heating is performed by induction heating the mold while moving the coil over the entire cavity surface of the mold while the induction heating coil is energized. It is possible to uniformly heat the entire cavity surface of the mold by suppressing the occurrence of temperature unevenness, which has been a problem with the conventional heating method in which the coil is energized with the heating coil fixedly in place. it can.

In addition, when water vapor is sprayed onto the cavity surface of the mold in parallel with induction heating by energization of the induction heating coil, condensed water adheres to the cavity surface when the mold temperature is 100 ° C. or less, and the latent heat at that time is The temperature can be raised to 100 ° C. Note that the condensed water adhering to the cavity surface can be removed by dropping by gravity when the hot air or the mold has a vertically split structure. Further, in parallel with induction heating by energization of the induction heating coil, water vapor is blown to the cavity surface of the mold through a nozzle hole drilled in the peripheral surface of the pipe conductor constituting the induction heating coil. The water vapor blown out from the nozzle hole through the nozzle hole instantly diffuses to every corner of the entire cavity surface of the mold and transfers heat to the mold. Thereby, generation | occurrence | production of the temperature nonuniformity by induction heating of an induction heating coil can be suppressed, and the cavity surface whole region of a metal mold | die can be heated uniformly in a short time. In addition, by supplying the steam generated by the steam generator through the pipe conductor of the induction heating coil, there is an advantage that the steam can be heated to a high temperature by using Joule heat generated in the coil itself by energization. In addition, since a coil conductor becomes a member which served as the induction heating coil and water vapor | steam blowing, it becomes a compact structure.
Further, it is effective to use superheated steam having a temperature of several hundred degrees Celsius as the steam. This superheated steam has much higher heat capacity and heat transfer coefficient than hot air, etc., and the superheated steam blown out from the nozzle holes instantly diffuses to every corner of the inner surface of the mold and does not generate drainage. Heat is transferred to the entire area.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the induction heating apparatus of the metal mold | die applied to 1st Example of this invention, (a) is a model perspective view showing the shape of the transverse induction heating coil interposed in the metal mold | die, (b) It is a schematic top view showing the movement range of the reciprocating motion added to the transverse type induction heating coil. It is a block diagram of the induction heating apparatus of the metal mold | die applied to 2nd Example of this invention, (a) is a schematic top view of a transverse type induction heating coil, (b) is an enlarged side view of the A section in (a) FIG.

  Embodiments of the present invention will be described below based on the embodiments shown in FIGS.

  First, the configuration and operation of the first embodiment according to claims 1 and 4 of the present invention will be described with reference to FIGS. 1 (a) and 1 (b).

  That is, in this embodiment, a transverse type induction heating coil interposed in a mold-matching surface of a mold having a split structure is moved back and forth over the entire cavity surface while the induction heating coil is energized. The mold is heated by induction. 1 is a mold with a split structure consisting of a fixed mold 2 and a movable mold 3, and 4 is a hollow copper pipe for low resistance and light weight. This is a transverse induction heating coil interposed between the dies 2 and 3. This transverse induction heating coil is composed of a hollow copper biconductor to reduce resistance and reduce weight. 5 is a coil unit (coil assembly) holding the coil 4, 6 is a high frequency power source, 7 is a coil connected to the coil unit 5 and reciprocally moves the transverse induction heating coil 4 over the entire width of the cavity surface of the mold 1. It is a drive device. Reference numeral 8 denotes a flexible connection line formed by bundling insulated thin wires, and connects the transverse induction heating coil 4 and the high-frequency power source 6.

  Here, the transverse induction heating coil 4 has a configuration in which a coil conductor is wound in a square shape in accordance with the shape (rectangular shape) of the mold 1, and the start end and the end of the coil are connected to the high frequency via the connection line 8. It is connected to a power source 6 so as to supply a high frequency current. The coil in the illustrated example is mounted on the coil unit 5 with the vertical height matched to the vertical size of the cavity surface of the mold 1 and the horizontal width set to approximately half the horizontal size of the mold 1. doing.

  A coil driving device 7 is connected to the coil unit 5, and the coil driving device 7 applies a periodic reciprocating motion to the coil unit 5, so that the transverse induction heating coil 4 is moved into the cavity of the mold 1. It is designed to move across the entire width along the surface. The moving range of the coil by this reciprocating motion is set in accordance with the entire area of the cavity surface of the mold.

  With the above configuration, when the mold 1 is preheated prior to the injection of the molten metal, the transverse induction heating coil 4 is opposed to the mold-matching surface between the fixed mold 2 and the movable mold 3 as shown in the figure. The high frequency current is applied to the coil from the high frequency power source 6 while the coil unit 5 is periodically reciprocated over the entire width of the cavity surface of the mold in the direction of arrow P by the operation of the coil driving device 7. To do. As a result, the region where induced current (eddy current) is induced on the cavity surface of the mold 1 is continuously displaced in the left-right direction as the coil reciprocates, and spreads over the entire cavity surface of the mold 1. As a result, it is possible to uniformly heat the entire cavity surface of the mold 1 while suppressing the occurrence of temperature unevenness, which has been a problem with the conventional heating method in which the induction heating coil is fixedly placed at a fixed position as in the past. can do.

  If the coil driving device 7 is configured to be driven in the vertical and horizontal two-dimensional directions, a transverse induction heating coil 4 smaller than the outer size of the mold 1 to be applied can be used. By heating this while moving over the entire cavity surface of the mold, it becomes possible to uniformly heat the entire cavity surface of the mold, thereby ensuring high versatility.

  When the cavity surface of the mold 1 is heated to a predetermined preheating temperature, the coil unit 5 is retracted from the mating surface of the mold 1, and then the fixed mold 2 and the movable mold 3 are fitted. Then, casting is performed by injecting molten metal.

  Next, the structure and operation of the second embodiment according to claims 2, 4 and 5 of the present invention will be described with reference to FIGS. 2 (a) and 2 (b). In this embodiment, the coil conductor of the transverse induction heating coil 4 is formed as a hollow pipe conductor made of a low resistance copper material or the like, and a large number of nozzle holes 4a are dispersed and perforated over the entire length of the conductor. The induction heating coil 4 is connected to the water vapor generator 8 so as to constitute a mold heating device.

  In the preheating process of the mold 1, the transverse induction heating coil 4 is inserted into the mating surface between the fixed mold 2 and the movable mold 3, and then the induction heating coil 4 is fed from the high frequency power supply 6 to the mold. Perform induction heating of mold 1. When the temperature of the cavity surface of the mold 1 reaches 100 ° C. or higher, superheated steam of 100 ° C. or higher (for example, superheated to a temperature of about 400 ° C.) sent from the steam generator 8 to the pipe conductor of the induction heating coil 4. Steam is sprayed on the cavity of the mold 1 through the nozzle hole 4a to perform heating. Thereby, heating of the metal mold | die 1 which used induction heating and superheated steam heating together is performed to predetermined temperature.

  In this case, the water vapor blown out from the nozzle hole 4 a of the transverse induction heating coil 4 is instantly diffused to every corner of the cavity surface of the mold 1 to transfer the retained heat of the superheated steam to the mold 1. Can do. As a result, condensate does not adhere to the cavity surface of the mold 1, and the occurrence of temperature unevenness, which becomes a problem in the conventional induction heating method, is suppressed as in the first embodiment. The entire area can be heated uniformly and efficiently.

  When the cavity surface of the mold 1 is heated to a predetermined preheating temperature, the transverse induction heating coil 4 is retracted from the mating surface of the mold 1, and then the fixed mold 2, the movable mold 3, And casting by injecting molten metal.

  Note that steam having a temperature of 100 ° C. may be used instead of the superheated steam. In this case, when water vapor fed to the pipe conductor of the induction heating coil 4 is sprayed on the cavity surface of the mold 1 in parallel with the induction heating by energization of the induction heating coil 4, the cavity surface is exposed to the cavity surface when the temperature of the mold 1 is 100 ° C. or less. Condensed water adheres, and the latent heat at that time is given to the cavity surface, and the temperature can be raised to 100 ° C. Condensed water adhering to the cavity surface can be removed by blowing hot air with a blower (not shown) or falling by gravity when the mold has a vertically split structure.

  When the cavity surface of the mold 1 is heated to 100 ° C., the spraying of water vapor is stopped, and the cavity surface of the mold 1 is heated to a predetermined preheating temperature by heating only by induction heating. The induction heating coil 4 is retracted from the mating surface of the mold 1, the fixed mold 2 and the movable mold 3 are fitted, and the molten metal is injected to perform casting.

  In addition, the coil driving device 7 described in the first embodiment can be applied to this embodiment. By using both the reciprocating movement of the induction heating coil and the blowing of superheated steam, the mold can be used. Can be more effectively performed.

DESCRIPTION OF SYMBOLS 1 Mold 2 Fixed type 3 Movable type 4 Transverse type induction heating coil 4a Nozzle hole 5 Coil unit 6 High frequency power supply 7 Coil drive device 8 Superheated steam generator

Claims (6)

In a mold heating method in which a transverse type induction heating coil is disposed on a mold-matching surface of a mold having a split structure, and a high-frequency current is supplied to the coil to heat the cavity surface of the mold. ,
A method for heating a mold, wherein the induction heating coil is inductively heated while being energized while moving the coil over the entire cavity surface of the mold. In the mold heating method in which a transverse type induction heating coil is disposed on the mating surface of the mold having a split structure, and a high frequency current is passed through the coil to heat the cavity surface of the mold,
In parallel with induction heating by energization of an induction heating coil, a mold heating method is characterized in that water vapor is blown onto the cavity surface of the mold to heat the mold.   3. The heating method according to claim 2, wherein a coil conductor of the induction heating coil is used as a pipe conductor, and a number of nozzle holes are dispersed and perforated on the peripheral surface, and water vapor supplied from the outside to the pipe conductor is passed through the nozzle hole to form a mold. A method for heating a mold, wherein the mold is sprayed on a cavity surface.   2. A mold for use in the heating method according to claim 1, further comprising driving means for moving a transverse type induction heating coil inserted in the mold mating surface over the entire cavity surface of the mold. Heating device.   A transverse type induction heating coil inserted in the mating surface of the mold is formed by winding a pipe conductor with a large number of nozzle holes dispersed on the peripheral surface, and includes a water vapor generator for supplying water vapor to the coil A mold heating apparatus for use in the heating method according to claim 2.   The method for heating a mold according to claim 2 or 3, wherein superheated steam at 100 ° C or higher is used as the water vapor.

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