JP6536799B2 - Injection mold - Google Patents

Description

  The present invention relates to a resin injection mold provided with a heating device.

  Conventionally, in an injection molding method of an injection molded product, an electric heater is disposed in the vicinity of the cavity of the mold, and the temperature in the vicinity of the cavity of the mold is raised above the glass transition point of the resin before injecting the resin. By flowing the resin into the mold while raising the temperature of the mold, it is possible to delay the solidification of the resin that occurs when the resin comes in contact with the mold during the flow, and transfer of the resin to the mold It can improve. Therefore, the glossiness of the molded product can be improved, and the weld line generated when the divided resin flows again can be suppressed by the product shape and the number of gate points. Then, the cooling water is allowed to flow into the mold after the resin filling is completed, so that the heated mold is cooled by the electric heater, and the resin is solidified to solidify the resin, with a high quality appearance. A molded article can be obtained (see, for example, Patent Document 1).

FIG. 9 is a cross-sectional view illustrating the configuration of a conventional mold, and shows the conventional mold structure described in Patent Document 1 mentioned above.
In FIG. 9, the mold insert is divided into a insert front member 51 having a cavity surface 50 and a insert back member 52 not having a cavity surface 50, and the insert back member 52 has a cooling circuit 54. Have. The insert front surface member 51 is formed from the back surface of the insert front surface member 51 toward the cavity surface 50, and includes a groove passing near the cavity surface 50. The electric heater 53 is accommodated in the groove, and the insertion back member 52 side is closed. The electric heater 53 is placed at the deepest portion of the groove formed in the insert front surface member 51. As a result, the electric heater 53 can be uniformly disposed in the vicinity of the cavity surface 50. Therefore, when the mold is heated by the electric heater, the mold is rapidly heated without unevenness in temperature rise, and a weld line is generated. It is possible to obtain a high gloss and high transparent molded article free of uneven transfer on the surface of the molded article appearance.

JP, 2010-264703, A

  However, in the conventional configuration, there is a problem that the time taken for the cooling process becomes long. Furthermore, in the case of molded articles of various appearances such as molded articles having a rib shape and a boss shape and having a projecting shape or a thick portion and having a non-uniform thickness, insufficient cooling of the mold partially occurs. There is also a problem that molded article appearance defects such as sink marks and insufficient transfer tend to occur easily. Generally, in consideration of only the cooling efficiency, it is desirable to arrange the cooling circuit 54 on the insert facing member 51 having the cavity surface 50. However, since the cooling circuit 54 is disposed on the insert back member 52 having no cavity surface 50 in the above-described conventional structure, a loss occurs in the cooling heat transfer from the insert back member 52 to the insert front member 51. It will Also, in practice, the electric heater 53 is deenergized in the cooling step, and the cooling medium is passed through the cooling circuit 54 to cool the core member 51, thereby cooling and solidifying the molded product in contact with the cavity surface 50. However, since the electric heater 53 has residual heat even after the electric heater 53 is deenergized, the resin in the thick portion, the rib shape and the boss shape requires time for cooling. Therefore, the cooling circuit 54 for quickly removing the remaining heat of the electric heater 53 disposed near the thick portion or the rib shape and the boss shape, the cavity surface 50 and the electric heat near the rib portion or the rib shape and the boss shape It needs to be placed near the heater 53. However, in order to place the cooling circuit 54 near the cavity surface 50 near the thick portion or rib shape and the boss shape and the electric heater 53, the distance between the cavity surface 50 and the electric heater 53 must be separated. With such a configuration, on the contrary, the time taken for the heating step of the mold will be long. Therefore, in the prior art, it is difficult to maintain the heating efficiency and the cooling efficiency regardless of the appearance shape of the molded product only by devising the arrangement positions of the electric heater 53 and the cooling circuit 54. Therefore, in a molded article having the thick portion, or a molded article having a rib shape and a boss shape, when molding is performed in a short time without spending a sufficient heating time or cooling time, sink marks and transfer of the outer appearance of the molded article Defects such as shortage occur.

  Here, the difference in cooling efficiency when a conventional mold configuration is applied to a black glossy appearance molded product having a boss or rib shape such as an exterior part of a car heater control panel will be described in detail using FIG. . In FIG. 10, since a molded article of a black glossy exterior part is used instead of a transparent part, it is a view of only the core on the side constituting the cavity surface, and the drawing of the core on the side not constituting the cavity surface is omitted. There is. First, the negative effects of the rib shape and the boss shape on the appearance of the molded product will be described.

  With respect to the general thickness 62 of the molded article 61, the thickness 63 of the rib-shaped portion and the thickness 64 of the boss are thick. Here, as shown in FIG. 10, the wall thickness is defined as the diameter of the largest circle that can be drawn in the cavity of that portion. The amount of heat required for cooling the resin molded product increases as the thickness increases, so when the electric heater 53 and the cooling circuit 54 disposed on the insert front member 51 and the insert rear member 52 are equally disposed, the ribs The cooling efficiency of the shape portion and the boss shape portion is deteriorated, and defects such as sink marks on the surface of the molded product and insufficient transfer occur. As a countermeasure therefor, conventionally, a method has been used in which the amount of heat given to the resin molded product is reduced by reducing the output of the electric heater disposed near the rib shape and the boss shape or changing the pitch of the electric heater. However, when the amount of heating is reduced, other appearance defects such as weld occur due to insufficient heating. In order to eliminate weld defects, there are many mass-production molding sites where the cooling time at the time of molding is extended while maintaining the heat quantity of the resin molded product. As described above, when continuous molding is performed in a short molding cycle, sink marks on the outer surface of a molded product, insufficient transfer, warpage, unevenness, and the like are likely to occur.

  The present invention solves the above-mentioned conventional problems, and it is an object of the present invention to ensure good appearance quality while performing continuous molding production with a short molding tact for molded articles having any appearance shape.

  In order to achieve the above object, an injection mold of the present invention is an injection mold for injecting a resin into a cavity formed by a plurality of inserts to form a molded article, wherein at least one of the inserts is Provided between the one or more heating devices provided in one, the one or more cooling circuits provided in the core, the respective heating device and the cavity surface of the cavity, and the space being empty from the peripheral core It has a high pore density and a high pore range.

  By providing the high pore range 8 between the cavity surface 2 and the electric heater 7, the electric heater 7 can be disposed close to the cooling circuit 9, and the heating efficiency of the cavity surface 2 can be increased by the high pore range 8. Since the electric heater 7 can be cooled efficiently while ensuring the above, even with molded articles of various shapes, good appearance quality can be ensured while performing continuous molding production with a short molding tact. .

Cross section illustrating the mold structure of the present invention Schematic explaining the temperature measurement position The figure which shows the temperature change of the cavity surface in the molding die of this invention The figure which shows the mode of the heat propagation by the heating of the electric heater in the molding die of this invention The figure which shows the appearance of the heat propagation by the heating of the electric heater in the conventional molding die The figure explaining the mode of the thermal expansion and thermal contraction of the high hole area in the molding die of this invention The figure explaining the mode of the thermal expansion and thermal contraction of the high hole area in the molding die of this invention The figure explaining the mode of the thermal expansion and thermal contraction of the high hole area in the molding die of this invention Sectional view illustrating the configuration of a conventional mold The figure which explains the difference of the cooling efficiency in the former die

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view illustrating the mold structure of the present invention, and is a drawing showing a mold configuration for molding a black glossy exterior molded product having a boss shape. The cavity surface 2 of the molded article 1 shown in FIG. 1 is mirror-polished, and the exterior surface of the molded article 1 is required to have a high gloss appearance surface. The mold is manufactured using metal lithography, etc., and the molding metal density can be freely changed. The mold is divided into a first insert 4 having the cavity surface 2 and a second insert 5 having a cavity surface 3 which is not a high gloss exterior surface.

  The first insert 4 has a cavity surface 2 of the molded product 1, an electric heater 7 which heats the cavity surface by passing an electric current, and a cooling circuit 9, and the outer periphery is made of low thermal conductive material 6 for heat insulation purpose. It is supposed to be covered. Instead of the low thermal conductive material 6, the outer periphery may be covered with a high-porosity material whose modeling density in metal photo-fabrication can be reduced easily and inexpensively. Further, a high pore range 8 for uniform heat transfer from the electric heater 7 to the cavity surface 2, which is a feature of the present invention, is disposed between the electric heater 7 and the cavity surface 2. The high vacancy range 8 is a shape having a vacancy inside. As for the pores, the density of the high pore range 8 is higher than that of the periphery of the high pore range 8. It is also possible to pass a gas cooling medium such as air through the high vacancy range 8, and the effect of removing the residual heat of the electric heater 7 can also be exhibited.

  The second core 5 has a cavity surface 3 which is a back surface of the molded product 1 not having a high gloss appearance surface, and is accompanied by a boss shape 10 for forming a boss. Since it does not have a high gloss appearance, there is no need for a special processing, and there is no need for the electric heater 7 for raising the temperature of the cavity surface. It has only a cooling circuit 9 for cooling and solidifying the molded article 1. Further, in order to take out the cooled and solidified molded product from the insert, a sleeve pin 41 for protrusion and a center pin 42 are provided at the end of the boss shape 10. Here, although the electric heater 7 has been described as an example, other heating devices may be used to heat the cavity surface.

  FIG. 2 is a schematic view for explaining the temperature measurement position. FIG. 3 is a view showing the temperature change of the cavity surface in the molding die of the present invention, and each of the cavity surface 2 for each molding process for molding the high-gloss exterior molded product having the boss shape 10 shown in FIG. It is the graph which showed the change of the die temperature in the measurement position. The temperature at each measurement position is the temperature 15 of the position of the cavity surface closest to the electric heater 7 and the temperature 16 of the position of the cavity surface of the position farthest from both the adjacent electric heaters 7 where the distance between the electric heaters 7 becomes wide. is there. In the graph of FIG. 3, the horizontal axis represents time (sec), and the vertical axis represents the mold temperature (° C.) of the cavity surface 2. When injection molding is performed, the mold is heated by the electric heater 7 from the mold opening / extraction step 11 before molding or one cycle before, and the cavity surface 2 is heated. Then, from the mold closing step 12 to immediately before the injection and pressure holding step 13, that is, before the resin is injected into the mold, the cavity surface 2 is heated to a temperature about 10 ° C. to 20 ° C. higher than the glass transition point 14 Be done. For example, when a polycarbonate resin is used for a molded article, since the glass transition point 14 is about 150 ° C., the temperature of the cavity surface 2 is set to about 160 ° C. to 170 ° C. When the temperature is set to this temperature, the portion where the flowing resin contacts is in a high temperature state, so if the temperature is raised only at the cavity surface 2, the solidification of the resin can be delayed and the weld line disappears be able to. Further, since the propagation of the molding pressure can be improved, the transfer of the resin to the mold can be improved, and a molded article in a high gloss state can also be obtained. However, it is not only necessary to make the mold surface temperature higher than the glass transition point 14 as in the prior art, as in the case of a high gloss component having a dark color or a dark high-gloss part or a molded product whose surface is textured. For example, in the case where a portion where the temperature of the cavity surface 2 becomes 180 ° C. or more occurs, disappearance of the weld line is possible but the temperature of the cavity surface 2 is inflow resin of the portion of 160 ° C. and the portion of 180 ° C. Since the transfer rate is different, the problem of transfer unevenness of the appearance of the molded product newly occurs. In the case of a molded product whose surface is made of satin, resin penetration into the concave portion of the satin increases further in places where the temperature of the cavity surface 2 is high, and therefore the depth of the satin partially changes and the appearance quality is uneven It looks like that. In order to solve this problem, in the case of a mold of a black high gloss part having a conventional rib shape or boss shape, the electric heater 7 may be disposed uniformly and at equal intervals from the cavity surface 2. However, since the cooling circuit can not be evenly and evenly spaced from the cavity surface 2, injection standby is performed and molding is started until the temperature unevenness of the cavity surface 2 of the mold generated during cooling is reduced. , Molding tact has been long. On the other hand, according to the present invention, even in the case of a black high gloss component having a rib shape or a boss shape, the electric heater 7 and the cooling circuit can be arranged uniformly and equally spaced from the cavity surface. The setting of the high vacancy range 8 is a very effective means for shortening the molding tact time (especially shortening of the cooling step 17) and improving the appearance quality. That is, as shown in FIG. 1, by providing the high pore range 8 between the cavity surface 2 and the electric heater 7, the electric heater 7 can be disposed close to the cooling circuit 9, and the high pore is By the range 8, the heating efficiency of the cavity surface 2 is secured, and the cooling of the electric heater 7 can be efficiently performed while the cavity surface 2 is uniformly heated. Therefore, even with molded articles of various shapes, good appearance quality can be ensured while performing continuous molding production with a short molding tact. Moreover, it is preferable to optimize the arrangement position, the shape, and the size of the high hole area 8 in accordance with the shape of the molded product.

  FIG. 4 and FIG. 5 are diagrams showing the state of heat propagation by the heating of the electric heater 7. The same or corresponding portions as in FIGS. 1 to 3 are denoted by the same reference numerals, and a part of the description will be omitted. As a comparative example, FIG. 4 sets the high-porosity material range 8 between the cavity surface 2 of the first insert 4 of the present invention and the electric heater 7 described above, and FIG. 5 sets the high-porosity material range FIG. 2 is a cross-sectional view showing a prior art. In this comparative example, the arrival of heat propagation t1 seconds after the start of heating is taken as a first heat propagation 21, and the arrival of heat propagation after t2 seconds is taken as a second heat propagation 22.

  Assuming that the heating time taken to the completion of the heating step is t2 seconds, when raising the temperature of the cavity surface 2 by heating due to heat propagation, it is the intersection point of the second heat propagation 22 of two adjacent electrothermal heaters 7, It is necessary to raise the temperature up to the glass transition point of the resin at the lowest temperature rise point 23 (point represented by reference numeral 16 in FIG. 2) located above 2. At this time, by setting the high vacancy range 8 between the electric heater 7 and the cavity surface 2 as shown in FIG. 4, it is possible to make the time for heat propagation to reach the cavity surface 2 uniform. The high vacancy range 8 has a low material density and an air layer, so the thermal conductivity is lower than that of the other low vacancy range in which the electric heater 7 and the cooling circuit 9 are installed. The first core 4 is formed by metal light molding or the like. In order to make the description easy to understand, a portion of the first core 4 around the high pore range 8 and made of a metal density equivalent to that of a general mold steel is called a low pore range. Since the heat conductivity of the high vacancy range 8 is lower than that of the low vacancy range, heat propagation from which heat should be uniformly propagated concentrically of the electric heater 7 is transferred from the low vacancy range to the high vacancy range 8 The heat propagation only in the high vacancy range 8 is delayed when C. reaches, and the heat propagation 22 is not circular and the heat propagation 22 is distorted in the direction in which the high vacancy range 8 exists. Then, as in the heat propagation 22 of FIG. 4, the heat propagation is such as to reach the cavity surface uniformly. Although it is preferable to set the shape of the high vacancy range 8 in each case depending on the shape of the molded product, the shape can be determined by the distance from the center of the electric heater 7 to the cavity surface 2. When the distance is short, the high vacancy range 8 becomes long, and when the distance from the center of the electric heater 7 to the cavity surface 2 is long, the high vacancy range 8 becomes short, so a triangular or sector shape as shown in FIG. Then, it becomes the most uniform heat propagation. More specifically, the high vacancy range 8 is disposed such that the apex of a triangle or the center of a sector is disposed on the cavity side, that is, the width narrows toward the cavity surface to form a tapered shape. Here, among the distances from the center of the electric heater 7 to the cavity surface 2, the distance passing through the low vacancy range is T, the distance passing through the high vacancy range 8 is K, the thermal conductivity in the low vacancy range is Tn, the high vacancy When the thermal conductivity of the pore range 8 is Kn, it is preferable to set the high vacancy range 8 such that T × Tn + K × Kn is equal. In FIG. 4, the portion passing through the low vacancy range is divided into two portions across the high vacancy range 8 and each is indicated by T. The distance T passing through the low vacancy range in the above equation is the sum of the two distances. Therefore, it becomes possible to arrange the electric heater 7 at a free position. It becomes possible to arrange the electric heater 7 in the vicinity of the cooling circuit 9. If the temperature of the cavity surface 2 is raised above the glass transition point of the resin, the electric heater 7 is disposed in the vicinity of the cooling circuit 9, so the temperature of the cavity surface 2 closest to the electric heater 7 becomes too high. To keep the mold temperature low when entering the cooling process. That is, even if the time for the cooling process is reduced, the mold can be sufficiently cooled, the heat in the resin can be cooled, and sufficient solidification can be promoted before taking it out of the mold, so the appearance such as sink marks or warpage deformation Poor quality can be prevented.

  In the case where the high vacancy range 8 as in the conventional FIG. 5 is not set, heat is uniformly transmitted concentrically of the electric heater 7. When the lowest temperature rising point 23 is raised to a temperature higher than the glass transition point of the resin, the highest temperature rising point 24 is heated to a temperature which is originally unnecessary. Since the cooling is required, it takes time to cool the resin to a temperature that allows removal of the resin by cooling the cavity surface 2. As described above, even after the electric heater 7 is turned off in the cooling step, the electric heater 7 has residual heat, and the higher the temperature of the maximum temperature rising point 24, the more the electric heater 7 in the cooling step. It takes time to remove the residual heat. As a result, the molding cycle takes a long time, and the temperature difference between the highest temperature rise point 24 and the lowest temperature rise point 23 also increases in the cooling step, and the appearance unevenness due to the difference in resin shrinkage at the initial stage of cooling also occurs. It will be easier. Also with regard to this problem, occurrence of the appearance unevenness can be prevented by early removing residual heat of the electric heater 7 by air cooling to the high pore range 8 in the present invention of FIG. 4. That is, a gas injection device (not shown) is further provided, and a gas injection device (not shown) injects gas from the outside into the pores of the high pore range 8 and flows the gas into the high pore range 8. The residual gas can be removed early by the flowing gas.

  Note that if Cr and NiAl precipitation hardened steel (CENA1) are used for the first core 4 as an example of the core, its thermal conductivity is 28.1 W / mK, and the pore density of the high pore range 8 is In the case of 20%, the thermal conductivity is 16.2 W / mK.

  6 to 8 are diagrams for explaining the thermal expansion and thermal contraction of the high pore range in the molding die of the present invention, and the temperature rise of the high pore range 8 set between the electric heater 7 and the cavity surface 2 It is drawing which showed the detail of thermal expansion and thermal contraction in a process and a cooling process. FIG. 6 is a view of the mold initial state in which the electric heater 7 is inserted and fixed to the first insert 4 having the cavity surface 2 constituting the appearance surface in which the high pore range 8 is set. FIG. It is a figure of the temperature rising process which carried out the electric heating of the electric heater 7 from the above. Moreover, FIG. 8 is a figure showing the state at the time of removing the residual heat of the electrothermal heater 7 through air in the high void | hole area | region 8, when it progresses to the following cooling process from the metal mold | die of a temperature rising state.

  As shown in FIG. 6, in the mold in the initial state, a clearance 31 for inserting the electric heater 7 is provided in the hole of the first insert 4. For example, if SUS304 is used as the main material of the electric heater 7, its thermal expansion coefficient is 17.5 × E-6 (1 / K), the coil heater diameter 25 is 6 mm, and the temperature is about 500 ° C. when heated. If it goes up, the thermal expansion causes the coil heater diameter to increase by about 0.05 mm, so that the initial clearance of 0.01 to 0.02 mm causes no problem in use. Next, as shown in FIG. 7 in the state where the electric heater 7 is energized and heated, the electric heater 7 becomes 500 ° C., and as a result of thermal expansion, the clearance 31 with the first insert 4 becomes smaller. The electric heater 7 contacts the hole. From this time point, heat transfer starts rapidly, and the cavity surface 2 of the first core 4 is rapidly heated. In this state, the resin is injected and injected when the temperature of the entire cavity surface 2 rises above the glass transition point of the resin. Next, the process proceeds to a cooling process for cooling and solidifying the injected and injected resin. In the cooling step, the flow of a liquid medium such as cooling water to the cooling circuit, the interruption of energization to the electric heater 7, and the cooling through the gaseous medium such as air to the high pore range 8 are simultaneously performed.

  Here, in particular, air cooling to the high pore range 8 which is a feature of the present invention will be described in detail. In this case, a fan (not shown) capable of blowing the gas to the high hole area 8 is further provided. The high vacancy range 8 operates the heat conduction from the electric heater 7 to the cavity surface 2 to perform uniform heating, and also functions to remove the residual heat of the electric heater 7 in the cooling process. A state in which the air is allowed to pass through the high hole area 8 by the blower and the residual heat of the electric heater 7 is removed simultaneously with the interruption of the energization of the electric heater 7 is shown in FIG. Here, since the electric heater 7 is deenergized and air cooling is performed from the high pore range 8 contrary to the heating in FIG. 7, the electric heater 7 is cooled and causes thermal contraction. Since it is also cooled simultaneously, heat contraction occurs with the center of the high vacancy range 8 as the origin. Therefore, the clearance 32 between the electric heater 7 and the electric heater 7 insertion hole of the first insert 4 is different from the clearance 31 in the mold initial state in FIG. Clearance occurs. As a merit of this clearance 32 becoming large, it transfers to the die temperature rising process again after taking out the cooled and solidified molded product, but the cavity surface 2 closest to the electrothermal heater 7 at the time of the thermal expansion of the electrothermal heater 7 at that time Since the heat transfer to the substrate can be delayed most, the problem of excessive rise in temperature of the cavity surface 2 closest to the electric heater 7 can be resolved.

  From the above, by reducing the excess heating of the cavity surface 2 closest to the electric heater 7 and suppressing the amount of heat necessary for cooling, the cooling efficiency of the mold can be improved, and the residual heat of the electric heater 7 is early Since heating and cooling of the mold can be accomplished in a short time, continuous molding production with a short molding cycle time, shrinkage of the thick resin part, warpage after removal from the mold, etc. A molded article can be obtained with no appearance and with good appearance quality of the molded article. That is, not only a molded product having a uniform thickness which is constituted by a curved surface defined by a flat surface or a curved surface close to a flat surface as conventional, but also a molded product having a thick portion, a rib, and a boss shape By providing a range of high-porosity mold material at a position where it is necessary to promote heating in the vicinity of a meat part, etc., the mold can be heated and cooled in a short time, and continuous molding production with short molding tact is performed. However, the molded article can be obtained without any defect in the appearance of the molding such as weld lines and lack of gloss. In addition, by cooling the mold with high efficiency such as air cooling in the high pore range, the mold and resin can be cooled in a short time, and continuous molding production with a short molding tact can be performed. It is possible to alleviate the shrinkage of the thick resin part due to insufficient cooling and the warpage deformation after taking it out from the mold, and in particular to stably obtain an injection molded article having an appearance of good quality in an exterior molded part it can.

  The molded product molded using the injection molding die of the present invention also has the function of a black glossy exterior part such as an exterior panel for car heater control or an exterior panel for car navigation system, and has a boss or rib shape. And molded articles of mechanical parts.

  In the above description, the molding die according to the present invention and the molding method according to the present invention are applied to a variety of exterior molded products by continuous molding with a high productivity in a short molding time if only an example is shown. However, a molded article can be obtained with a good appearance quality without weld lines, lack of glossiness, sink marks and warpage. For example, according to the mold configuration shown in the first embodiment, if a molded product having good productivity and good appearance quality can be obtained with an exterior molded part, makeup after molding such as painting is performed. The process can be reduced, resources such as paint can be reduced, and resin members can be recycled.

  The present invention can ensure good appearance quality while performing continuous molding production with a short molding tact for molded articles of any appearance shape, and is useful for a resin injection molding die and the like.

Reference Signs List 1 molded product 2 cavity surface 3 cavity surface 4 first insert 5 second insert 6 low thermal conductive material 7 electric heater 8 high hole area 9 cooling circuit 10 boss shape 11 mold opening / extracting process 12 mold closing process 13 injection / maintenance Pressure process 14 Glass transition point 15 Temperature 16 Temperature 17 Cooling process 21 1st heat propagation 22 2nd heat propagation 23 lowest temperature rising point 24 highest temperature rising point 31 clearance 32 clearance 41 sleeve pin 42 center pin 50 cavity surface 51 insert surface The member 52, the insert back member 53, the electric heater 54, the cooling circuit 61, the molded product 62, the general thickness 63, the thickness of the rib shaped portion 64, the thickness of the boss shaped portion

Claims (5)

An injection molding die for molding a molded article by injecting a resin into a cavity formed by a plurality of cores.
One or more heating devices provided in the at least one core;
One or more cooling circuits provided in the core;
An injection mold having a high vacancy range provided between the respective heating devices and the cavity surface of the cavity and having a vacancy density higher than that of the peripheral core.   The injection molding die according to claim 1, wherein each of the high hole areas is disposed on a shortest path connecting each of the heating devices and the cavity surface.   The injection mold according to claim 1 or 2, wherein the cross-sectional shape of the high hole range is a triangular shape or a sector shape whose width becomes narrower as it approaches the cavity surface.   In each line segment connecting the heating device and the cavity surface through the high vacancy range, a length passing through the high vacancy range is K, and a length passing through the core other than the high vacancy range is T Assuming that the thermal conductivity of the high vacancy range is Kn and the thermal conductivity of the core is Tn, the high vacancy range has a shape such that T × Tn + K × Kn is equal in each of the line segments. The injection mold according to any one of claims 1 to 3, characterized in that It further comprises a gas injection device for passing a gas medium in the high vacancy range,
5. The method according to any one of claims 1 to 4, wherein, when the cavity is cooled by the cooling circuit, a gas medium is injected from the gas injection device into the high-hole area to cool the cavity. The injection mold as described in.

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