JP6020822B2 - Injection mold and injection molding method - Google Patents

Description

  The present invention relates to an injection mold used for molding a resin molded product and an injection molding method using the same.

  Conventionally, in an injection molding method for resin molded products such as exterior molded products, an electric heater is disposed in the vicinity of the molding region of the molded product in the mold, and before the resin is injected, the vicinity of the molded product of the mold is subjected to glass transition of the resin. There was one that raised the temperature above the temperature (see Patent Document 1). By allowing the resin to flow into the mold with the mold heated, the resin solidification that occurs when the resin contacts the mold during flow can be delayed, improving the transfer of the resin to the mold. it can. Therefore, the glossiness of the molded product can be improved, and the weld line that is generated when the divided resin flows meet again can be suppressed depending on the product shape and the number of gate points. Then, after filling the resin, the cooling water is flowed into the mold, the heated mold is cooled by the heater, and the resin is cooled, so that the resin is solidified and molded with a high quality appearance. Goods can be obtained.

FIG. 8 is a cross-sectional view illustrating the configuration of a conventional mold and shows the mold structure described in Patent Document 1. In FIG.
In FIG. 8, the mold insert 55 constituting the mold forming region is divided into an insert front member 51 having a cavity surface 50 and an insert back member 52 having no cavity surface 50. A groove 56 extending from the back surface of the nesting front member 51 to the vicinity of the cavity surface 50 is formed in the nesting front member 51. The electric heater 53 is accommodated in the groove 56, and the groove 56 is closed by the nesting back member 52. Then, the electric heater 53 is placed at the deepest portion of the groove 56 formed in the telescopic member 51. As a result, the electric heater 53 can be uniformly arranged in the vicinity of the cavity surface 50, and when the mold is heated by the electric heater 53, the mold is rapidly heated without uneven temperature rise, and a weld line is generated. Was suppressed.

JP 2010-264703 A

  However, the conventional mold has the cooling circuit 54 in the insert back member 52 that does not have the cavity surface 50, but does not have the cooling circuit 54 in the insert surface member 51 that has the cavity surface 50. Therefore, there is no cooling circuit 54 for cooling the nested surface member 51 when the heat of the resin flowing into the molding region moves to the nested surface member 51. Therefore, the nesting front member 51 can only be cooled by heat radiation from the contact surface with the nesting back member 52, and the cooling efficiency is poor. Therefore, when continuous molding is performed with a short molding cycle, the heat of the resin cannot be sufficiently cooled, and the molded product cannot be removed from the mold with the resin completely solidified. It was. Therefore, there has been a problem that warp deformation occurs due to thermal shrinkage after the removal. Or there is a problem in that the quality of the exterior molded product is deteriorated because sinkage occurs in a portion of the molded product that is insufficiently cooled and where the resin is thick.

  In some cases, the nest back member 52 is held by contacting the nest back member 52 with the electric heater 53, and the nest back member 52 is heated from the contact surface of the electric heater 53. As a result, not only the cavity surface 50 that originally needs to be heated but also the nested back member 52 is heated unnecessarily, and the temperature of the cooling circuit 54 rises to cool the heated heat. In addition, there is a problem that warpage deformation and sinking are generated as described above by further deteriorating the cooling performance.

  An object of the present invention is to solve the above-mentioned conventional problems, and to provide a molded product in a good state without impairing the appearance quality of the exterior molded product even when continuous molding production with a short molding tact is performed. And

  In order to achieve the above object, an injection mold according to the present invention is an injection mold formed of a plurality of molds and injecting a resin into a molding region to form a molded product, A first nest that is in contact with the molding region, which is one component of the mold, a groove that is formed in the first nest and spaced apart from the molding region, and one of the molds that is inserted into the groove A second nest serving as a component; a heater provided at a boundary between the first nest and the second nest; a cooling circuit for cooling the mold; and a first nest for holding the heater A heat transfer range, and a second heat transfer range of the second nested holding the heater, the heat transfer efficiency from the heater to the second heat transfer range is from the heater to the first Less than the heat transfer efficiency to the heat transfer range The features.

  As described above, the upper mold is composed of the first insert and the plurality of second inserts, the heater is provided at the boundary between the first insert and the second insert, and is held by the first insert and the second insert. The heat conduction efficiency from the heater to the second nesting is made smaller than the heat conduction efficiency from the heater to the first nesting, thereby improving the heating and cooling performance of the mold and producing a continuous molding with a short forming tact. Even if it performs, it can provide the molded product of a favorable state, without impairing the external appearance quality of an exterior molded product.

Sectional drawing which shows the structure of the metal mold | die for injection molding of this invention The figure which shows the temperature change of the injection mold of this invention The principal part expanded sectional view explaining the structure of the metal mold | die for injection molding of this invention The figure explaining the state change by heating and cooling of the injection mold of this invention The figure explaining the heating process in the metal mold | die for injection molding of this invention The figure explaining the holding | maintenance state of the cartridge heater of the injection mold of this invention Cross-sectional view of the main part showing a configuration example of an injection mold according to the present invention Sectional drawing which illustrates the structure of the conventional metal mold | die

In some cases, an exterior part of a product such as a thin TV or a car navigation system is molded as a resin molded product using an injection mold.
Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing a configuration of an injection mold according to the present invention, and is a drawing showing a mold configuration for molding an exterior molded product.
In FIG. 1, an injection mold 40 is composed of an upper mold 41 and a lower mold 42, and a space formed when the upper mold 41 and the lower mold 42 are combined is a molding region of a resin molded product. 1 is configured. The cavity surface 2 in the molding region 1 becomes an outer layer surface of the resin molded product, and when a high gloss surface is required, a mirror surface is applied. The upper mold 41 is divided into a first insert 3 and a second insert 4. The first nesting 3 has a cavity surface 2 in the molding area 1 and a first nesting cooling circuit 5. Further, a cartridge heater 6 that is a heater that heats the mold by flowing an electric current is provided in a boundary region between the first insert 3 and the second insert 4 of the upper mold 41, and the cartridge heater 6 is attached to the mold. Fixed (not shown). The half area of the cross section of the cartridge heater 6 is in contact with the first nest 3 or held at a predetermined interval, and the other half is in contact with the second nest 4 or is held at a predetermined interval. . The region where the cartridge heater 6 and the first insert 3 face each other is the first heat transfer range 7, and the region where the cartridge heater 6 and the second insert 4 face each other becomes the second heat transfer range 8, and the second heat transfer range 8 The first heat transfer range 7 is located closer to the cavity surface 2. Here, when the cartridge heater 6 is cylindrical, the first heat transfer range 7 and the second heat transfer range 8 are semicylindrical. The first heat transfer range 7 of the first insert 3 and the second heat transfer range 8 of the second insert 4 constitute a portion for holding the cylindrical cartridge heater 6. The positional relationship between the cartridge heater 6 and the first nesting cooling circuit 5 is such that the cartridge heater 6 is positioned closer to the molding region 1 as shown in FIG. The first nesting cooling circuit 5 is arranged at a position farther from the molding region 1 than the cartridge heater 6 so as to sandwich the cartridge heater 6 between the second nesting 4 and the second heat transfer range 8 of the second nesting 4. One or a plurality of first nested cooling circuits 5 are arranged between the cartridge heaters 6 so as to surround the molding region 1. That is, the shortest distance between each cartridge heater 6 and the molding region 1 is shorter than the shortest distance between each first nested cooling circuit 5 and the molding region 1, and the cartridge heater 6 is provided within a certain distance from the molding region 1. Each first nested cooling circuit 5 is disposed so as to surround the cartridge heater 6 and the molding region 1.

  As described above, the injection mold according to the present invention is provided with the cartridge heater 6 at the boundary between the first insert 3 and the second insert 4 and is held by the first insert 3 and the second insert 4. The heat conduction efficiency from the heater 6 to the second insert 4 is smaller than the heat transfer efficiency from the cartridge heater 6 to the first insert 3. With such a configuration, the mold heating and cooling performance is improved, and even in the case of continuous molding production with a short molding tact, the molded product in a good state is provided without impairing the appearance quality of the exterior molded product. can do.

  FIG. 2 is a graph showing the temperature change of the injection mold of the present invention, and is a graph showing the mold temperature of the cavity surface 2 (see FIG. 1) for each molding process for molding an exterior molded product. . In FIG. 2, the horizontal axis represents time (sec), and the vertical axis represents the mold temperature (° C.) of the cavity surface 2 (see FIG. 1).

  When injection molding is performed, the mold for injection molding is heated by the cartridge heater from the mold opening / removing step 9 before molding or one cycle before, and the cavity surface is heated. The temperature of the cavity surface is about 10 ° C. to 20 ° C. higher than the glass transition temperature 12 of the resin from the mold closing process 10 to immediately before the injection / holding process 11, that is, before the resin is injected into the mold. Let the temperature rise. For example, when an ABS resin is used as the molding resin, the temperature of the cavity surface is set to about 120 ° C. to 130 ° C. with respect to the glass transition temperature 12 of about 110 ° C. When the temperature is set at this temperature, if only the cavity surface is heated, the portion where the flowing resin comes into contact is in a high temperature state, so that the solidification of the resin can be delayed. Therefore, in addition to the disappearance of the weld line, the propagation of molding pressure can be improved, so that the transfer of the resin to the mold can be improved and a molded product in a high gloss state can be obtained. Furthermore, if a product with good productivity and good appearance quality can be obtained, the post-makeup process after molding such as painting can be reduced, and resources such as paint can be reduced. The resin member can be recycled. Therefore, if the temperature is increased only on the cavity surface due to the first heat transfer range, there is no problem in molding, and even if the mold temperature in the second heat transfer range located on the opposite side of the cavity surface is increased, the quality of the molded product It doesn't make sense to improve. On the other hand, when the mold is cooled in the cooling step 13 from the injection / holding step 11 in FIG. 2, the cooling in the vicinity of the second heat transfer range is required, and the cooling efficiency is lowered. When the continuous molding production is short, as described above, warpage deformation and sink marks of the molded product occur, and the appearance quality deteriorates. Therefore, it is desirable that the heat conduction of the constituent material of the second nesting in the second heat transfer range is lower than the constituent material of the first heat transfer range.

FIG. 3 is an enlarged cross-sectional view of a main part for explaining the configuration of the injection mold of the present invention, and shows the details of the assembled state of the first insert 3 and the second insert 4.
As shown in FIG. 3, the groove | channel 43 for inserting the 2nd nest | insert 4 is provided in the surface on the opposite side to the cavity surface 2 of the 1st nest | insert 3, and the front-end | tip part of the 2nd nest | insert 4 is inserted there. At this time, the second nesting flange surface 14 is provided on the second nesting 4, the second nesting flange surface 14 is brought into contact with the surface of the first nesting 3, and the second heat transfer range at the tips of the cartridge heater 6 and the second nesting 4 is provided. The second heat transfer range clearance 15 may be formed between the two. At the same time, since the second nesting 4 does not push down the cartridge heater 6 by this configuration, the first heat transfer range clearance 16 formed between the cartridge heater 6 and the first heat transfer range 7 of the first nesting 3 is Shortening can be suppressed. In general, the smaller the clearance between the cartridge heater 6 and the mold is, the smaller the distance between the cartridge heater 6 and the first insert 3 and the second insert 4 is, and heat conduction to the mold is improved. The mold can be heated.

  Here, as described above, in order to perform high-efficiency heating and cooling in a short time, when the temperature of the cavity surface 2 is raised by heating the first nest 3, the second nest 4 is not heated excessively. Even if heat is transmitted to the second nesting 4, the second nesting 4 is controlled separately from the first nesting cooling circuit 5 without transmitting the heat to the first nesting 3 as much as possible. It is better to cool the nest 4 alone. Therefore, the contact surface between the first nesting 3 and the second nesting 4 may be only the second nesting flange surface 14, and the other surface may be provided with an air heat insulating layer 17. Heat conduction from the two nestings 4 to the first nesting 3 can be prevented. Further, since the second nesting 4 is heated by the cartridge heater 6, the temperature of the second nesting 4 is set to about 10 ° C. from the first nesting 3 by further providing a second nesting cooling circuit 18 and flowing cooling water. It can also be kept low.

  Further, in order to more efficiently heat and cool the first insert 3, it is effective not to conduct the heat of the first insert 3 to the fixed side mold plate 19. The second insert 4 is attached to the first insert 3. It is preferable to further provide a heat insulating plate 20 for fixing, and use a material having low thermal conductivity, such as SUS304, for example. In this case, the thermal conductivity is 16.2 W / mK. If, for example, cold die steel (SKD11) is used for the first insert 3, the thermal conductivity is 22.2 W / mK. Therefore, the heat conduction of the first insert 3 can be improved, and the first insert 3 can be heated and cooled more efficiently. Also, in the second nesting 4, for example, if a material with low thermal conductivity such as SUS304 is used, the thermal conductivity is 16.2 W / mK. Since it is possible to prevent the effect of cooling by the two-nested cooling circuit 18 from being transmitted to the first nesting 3, it is possible to further improve the thermal responsiveness of the first nesting 3.

  Thus, by the injection mold and the injection molding method, the heat conduction efficiency from the cartridge heater 6 to the second nest 4 is lower than the heat conduction efficiency from the cartridge heater 6 to the first nest 3. The cavity surface 2 can be efficiently heated and cooled, and even with continuous molding production with a short molding tact, the weld line, lack of gloss, sink marks on the thick resin part, and warpage after removal from the mold It is possible to obtain a molded product having no appearance and good appearance quality.

  FIG. 4 is a diagram for explaining the state change due to heating and cooling of the injection mold according to the present invention, and shows the transition of clearance between the first insert 3 and the second insert 4 and the cartridge heater 6 in the heating and cooling step. FIG. 4A is a mold state diagram during cooling, and the second heat transfer range clearance 15 is formed by the second insert 4 and the cartridge heater 6. FIG. 4B is a mold state diagram at the time of heating, and a second heat transfer range clearance 15 is formed by the second insert 4 and the cartridge heater 6 as in FIG. 4A. In addition, the same code | symbol is attached | subjected to the part which is the same as that of FIGS. 1-4, or an equivalent part, and one part description is abbreviate | omitted.

  In general, the smaller the second heat transfer range clearance 15 is, the smaller the distance between the cartridge heater 6 and the second insert 4 is, and the heat conduction efficiency is improved so that the heat of the cartridge heater 6 is transferred to the second insert 4. Improves heating efficiency because it is easier to communicate. Therefore, the temperature of the 2nd nest | insert 4 will rise more than needed at the time of a heating, and the efficiency at the time of cooling will deteriorate. Therefore, by increasing the second heat transfer range clearance 15, the contact area between the cartridge heater 6 and the second insert 4 is reduced, and it becomes difficult to transfer the heat of the cartridge heater 6 to the second insert 4. be able to. However, when the second heat transfer range clearance 15 exceeds a certain interval, for example, 0.5 mm, the interval between the cartridge heater 6 and the second nest 4 is too wide and the heat of the cartridge heater 6 is transmitted to the second nest 4. I can't do that. Therefore, only the cartridge heater 6 generates heat, the second insert 4 is not heated, and the cartridge heater 6 may be broken due to abnormal temperature rise and be damaged. Therefore, the second heat transfer range clearance 15 must not be set to exceed 0.5 mm, and similarly, the first heat transfer range clearance 16 must not be set to exceed 0.5 mm.

  Here, the thermal expansion coefficient of the second nesting 4 may be set larger than the thermal expansion coefficient of the first nesting 3. With this configuration, when the second heat transfer range clearance 15 in FIG. 4A is compared with the second heat transfer range clearance 15 in FIG. 4B, FIG. The second heat transfer range clearance 15 is preferable because it is smaller than that in the cooling step. This is because the thermal expansion coefficient of the second nesting 4 is set to be larger than that of the first nesting 3, so that when the mold is heated and the first nesting 3 and the second nesting 4 rise to the same temperature, the second nesting 4 The amount of thermal expansion of the second nesting protrusion amount 21 which is the depth of the first nesting 3 becomes larger than the thermal expansion of the first nesting amount 22 which is the depth of the groove 43. This is because the thermal expansion difference 23 is generated, and the second nesting 4 expands in the direction in contact with the cartridge heater 6, thereby reducing the second heat transfer range clearance 15. Further, the cartridge heater 6 is pressed in the direction of the first insert 3 by the expansion of the second insert 4, so that the first heat transfer range clearance 16 is simultaneously reduced. As described above, since the first heat transfer range clearance 16 is reduced, the interval between the cartridge heater 6 and the first insert 4 is reduced, and the heat of the cartridge heater 6 is easily transferred to the first insert 3. Heating efficiency can be improved.

  On the other hand, during cooling, the amount of thermal shrinkage of the second nesting protrusion amount 21 is larger than the amount of thermal shrinkage of the first nesting amount 22, so that the second nesting 4 shrinks away from the cartridge heater 6, The second heat transfer range clearance 15 is increased. In this way, the second heat transfer range clearance 15 during cooling is maximized during continuous molding. If the second heat transfer range clearance 15 at that time is set to 0.5 mm or more, the cartridge heater 6 as described above. May break and break due to abnormal temperature rise, the second heat transfer range clearance 15 needs to be set to 0.5 mm or less. Further, in order to improve the cooling efficiency of the mold, it is necessary not to give excessive heat to the mold, and the second heat transfer range clearance 15 at the time of cooling is not positively brought into contact with the cartridge heater 6. Is preferably set to 0.1 mm or more. Thus, by widening the distance between the cartridge heater 6 and the second insert 4, it is possible to minimize the heat of the cartridge heater 6 to the second insert 4 during cooling, thereby improving the cooling efficiency of the mold. Since the second heat transfer range clearance 15 at the time of cooling is not positively brought into contact with the cartridge heater 6, the force for urging the cartridge heater 6 toward the first insert 3 is inevitably reduced. One heat transfer range clearance 16 is also increased, and at the time of cooling, it is not necessary to transmit the heat of the cartridge heater 6 to the first insert 3 as much as possible, and further improvement of the cooling efficiency of the mold can be expected.

  For example, if cold die steel (SKD11) is used for the material of the first insert 3, the coefficient of thermal expansion is 11.7 × E-6 [1 / K], and the material of the second insert 4 is If aluminum is used, the thermal expansion coefficient is 23.1 × E-6 [1 / K]. And the 2nd heat transfer range clearance 15 at the time of cooling like the state of Fig.4 (a) is set to about 0.15-0.2 mm. In this case, the mold temperature is 50 ° C. When the mold temperature is increased to 130 ° C. from this state, the temperature difference is 80 ° C., and the first insert 3 and the second insert However, when the length of the second nesting protrusion 21 and the first nesting depth 22 is 100 mm, the difference in thermal expansion coefficient between the first nesting 3 and the second nesting 4 is as follows. It is calculated by 11.4 × E-6 [1 / K] × 80 ° C. × 100 mm, and the thermal expansion difference 23 is 0.09 mm. Since the cartridge heater 6 itself thermally expands due to heat generation, for example, if SUS304 is used as the main material, the coefficient of thermal expansion is 17.5 × E-6 [1 / K], and the diameter of the cartridge heater 6 If the temperature rises to about 500 ° C. during heating, the diameter increases by about 0.05 mm due to thermal expansion, and the second heat transfer range clearance 15 decreases by about 0.03 mm. Therefore, in combination with the above-described thermal expansion difference 23 of about 0.09 mm, the difference between the second heat transfer range clearance 15 during heating and cooling is about 0.12 mm. As a result, when the second heat transfer range clearance 15 at the time of cooling is 0.15 to 0.2 mm, the second heat transfer range clearance 15 is 0.03 to 0.08 mm at the minimum when the heating is completed. The heat efficiency by the cartridge heater 6 can be set so as to be the best in the process during continuous molding, and heat transfer by the cartridge heater 6 can be prevented during cooling.

  As described above, the relationship between the thermal expansion coefficients of the materials used for the first nesting 3 and the second nesting 4 is such that the first nesting thermal expansion coefficient is smaller than the second nesting thermal expansion coefficient. The clearance with the heater 6 can be increased during the cooling process to improve the cooling efficiency of the mold, and the clearance between the first insert 3 and the cartridge heater 6 can be decreased during the heating process to heat the mold. Since the efficiency can be improved, sufficient heating and cooling of the mold can be achieved in a short time, and even if continuous molding production with a short molding tact is performed, the weld line and lack of gloss, sink marks on the thick part of the resin, There is no warp deformation after taking out from the mold, and a molded product can be obtained with good appearance quality.

  FIG. 5 is a view for explaining the heating process in the injection mold according to the present invention, and shows the heat propagation due to the heating of the cartridge heater 6. In addition, the same code | symbol is attached | subjected to the part which is the same as that of FIGS. 1-5, or an equivalent part, and one part description is abbreviate | omitted. As a comparative example, FIG. 5A is a cross-sectional view when a through hole is formed in the first insert 3 and a cartridge heater 6 is inserted. In this comparative example, the arrival of heat propagation after t1 seconds from the start of heating is defined as first nested first heat propagation 24, and the arrival of heat propagation after t2 seconds is defined as first nested second heat propagation 25. Even if the mold is divided into the first nest 3 and the second nest 4, if the first nest 3 and the second nest 4 are made of the same material, the heat propagation is the same as described above. FIG.5 (b) is sectional drawing at the time of forming so that it may become the thermal conductivity of the 1st nest | insert 3 of this invention> the heat conductivity of the 2nd nest | insert 4, and the 1st nest after t1 second from a heating start The arrival of the first heat propagation 24 is the first nested first heat propagation 24, and the arrival of the second nested heat propagation is the second nested first heat propagation 26.

  When the heating time required to complete the heating process is t2 seconds, when the cavity surface 2 is heated by heating by heat propagation, it is the intersection of the first nested second heat propagation 25 of the two adjacent cartridge heaters 6. The temperature must be raised above the glass transition temperature of the resin at the lowest temperature rise point 27 on the cavity surface 2. At this time, as shown in FIG. Is propagated, it is heated up to the vicinity of the first nested cooling circuit 5 which is originally unnecessary, and the cooling is necessary. Therefore, it takes time to cool the cavity surface 2 to a temperature at which the resin can be taken out. Therefore, as shown in FIG. 5B, if the thermal conductivity of the first nesting 3> the thermal conductivity of the second nesting 4 is formed, the arrival of heat propagation is the first nesting first heat propagation 24 and the second nesting. It can be divided into two nested first heat propagations 26. Therefore, when the temperature of the cavity surface 2 is raised to the glass transition temperature or more of the resin by the first nested first heat propagation 24, the temperature of the second nested 4 is increased by the second nested first heat propagation 26. Less than one nesting 3. By maintaining the second insert 4 at a temperature lower than that of the first insert 3 during heating, the entire mold can be sufficiently cooled even when the cooling process time is reduced, and the heat inside the resin is cooled and taken out from the mold. Sufficient solidification can be promoted before. As a result, appearance quality defects such as sink marks and warp deformation can be prevented. In FIG. 5B, only the heat propagation from the cartridge heater 6 is shown as the first nested first heat propagation 24 and the second nested first heat propagation 26 for the sake of explanation. The heat propagates from 3 to the second nest 4. However, the heat propagation from the first insert 3 to the second insert 4 is omitted for easy understanding.

  Further, when the thermal conductivity of the second nesting 4 is set low as described above, if it is set too low, the temperature of the cartridge heater 6 is not transmitted to the mold, and the temperature of only the cartridge heater 6 rises. Failure of the cartridge heater 6 such as disconnection due to abnormal temperature rise will be caused. Therefore, it is desirable to set the thermal conductivity of the second nesting to 8 W / mK or more.

  As described above, the relationship between the thermal conductivities of the materials used for the first nesting 3 and the second nesting 4 is such that the first nesting thermal conductivity is greater than the second nesting thermal conductivity. The amount of heat required for cooling can be suppressed by reducing the amount of heating. Therefore, the cooling efficiency of the mold can be improved, sufficient heating and cooling of the mold can be performed in a short time, and even if continuous molding production with a short molding tact is performed, the sink of the thick part of the resin and the mold There is no warp deformation after taking out, and a molded product can be obtained with good appearance quality.

  FIG. 6 is a view for explaining the holding state of the cartridge heater of the injection mold according to the present invention, and shows the details when the cartridge heater 6 is held by the first insert 3 and the second insert 4. .

  In FIG. 6, when the cartridge heater diameter 28 is set to D mm, the clearance formed by the first nested heater holding radius 29 and the cartridge heater 6 is made as small as possible in order to further improve the heating efficiency of the cartridge heater 6. Things are desirable. However, for example, when SUS304 is used as the main material of the cartridge heater 6, its thermal expansion coefficient is 17.5 × E-6 [1 / K], the cartridge heater diameter is 6 mm, and the heating is about 500 ° C. If the temperature rises up to about 0.05 mm, the diameter increases by thermal expansion. Therefore, the thermal expansion due to the heat generated by the cartridge heater 6 itself is expected to be about 0.03 mm in radius, and the clearance of the processing accuracy error is preferably about 0.02 mm. Therefore, for example, when the cartridge heater diameter is 28 = 6 mm, the first nested heater holding radius 29 is set to about D / 2 + 0.05 mm = 3.05 mm. Further, as described above, even if the second insert 4 is heated, it does not affect the quality improvement of the molded product, and conversely, the cooling efficiency is deteriorated. Therefore, it is desirable to set a large clearance formed by the second nested heater holding radius 30 and the cartridge heater 6. Therefore, the second nested heater holding radius 30 is preferably set to about D / 2 + 0.1 mm = 3.1 mm. However, if it is too large, the second insert 4 does not contact the cartridge heater 6 at all, or even if it partially contacts, the force with which the second insert 4 presses the cartridge heater 6 becomes weak, and the cartridge heater 6 The clearance formed by the first nesting heater holding radius 28 and the cartridge heater 6 will not be pushed in the direction of the nesting 3 and the cartridge heater 6 will increase. Therefore, the second nesting heater holding radius center 31 which is the center of the second nesting heater holding radius 30 is moved about 0.07 mm from the center of the first nesting heater holding radius 29 to the first nesting 3 side, and the second nesting heater holding radius center 31 is moved. Preferably, a heater holding radius 30 is formed. In this way, the first nested heater holding radius 29 is made smaller than the second nested heater holding radius 30, or the second nested heater holding radius center 31 is further set to the first nested 3 from the center of the first nested heater holding radius 29. The clearance formed by the second nesting heater holding radius 30 and the cartridge heater 6 at the position of the cartridge heater pressing point 32 where the clearance becomes the smallest with the cartridge heater 6 of the second nesting 4 by moving to the side. Can be reduced to a value that substantially contacts about 0.03 mm, and the second nesting heater holding radius 30 and the cartridge heater 6 are pressed while partially pressing the cartridge heater pressing point 32 toward the first nesting 3 side. The clearance formed by the It is possible to reduce the heat to 4.

  As described above, the relationship between the first nested heater holding radius 29 and the second nested heater holding radius 30 is set such that the radius of the cartridge heater 6 <the first nested heater holding radius 29 <the second nested heater holding radius 30. Heating to the second nesting 4 can be reduced. Therefore, the cooling efficiency of a metal mold | die can be improved by reducing extra heating other than the cavity surface 2 and suppressing the calorie | heat amount required for cooling. Therefore, it is possible to heat and cool the mold sufficiently in a short time, and even if continuous molding production with short molding tact is performed, there is no sink of the thick part of the resin or warping deformation after taking out from the mold, and the molded product A molded product can be obtained with a good appearance quality.

  FIG. 7 is a cross-sectional view of an essential part showing a configuration example of an injection mold according to the present invention, and shows a structure in which a holding projection 33 is provided on the heater holding surface of the second insert 34 in the structure for holding the cartridge heater 6. It is a drawing. In addition, the same code | symbol is attached | subjected to the part which is the same as that of FIGS. 1-7, or an equivalent part, and one part description is abbreviate | omitted.

  As described above, for the purpose of improving the heating efficiency in the cartridge heater 6, it is desirable to make the clearance formed by the first nested heater holding radius 29 and the cartridge heater 6 as small as possible. Even if heated, there is no effect on the quality improvement of the molded product, and conversely, the cooling efficiency is deteriorated, so it is better not to heat as much as possible. Therefore, it is desirable to set a large clearance formed by the second nested heater holding radius 30 and the cartridge heater 6. Therefore, the second nested heater holding radius 30 is preferably set to about D / 2 + 0.1 mm. However, if it is too large, the cartridge heater 6 cannot be pressed against the first insert 3 and fixed, and the clearance formed by the first insert heater holding radius 29 and the cartridge heater 6 becomes large. . Therefore, in order to hold the cartridge heater 6 by the second insert 34, the holding projection 33 is provided, and the clearance formed by the holding projection 33 and the cartridge heater 6 is set to about 0.04 mm, so that the first While pressing toward the nesting 3 side, the clearance formed by the second nesting heater holding radius 30 and the cartridge heater 6 can be set large, and the heating of the second nesting 34 can be reduced.

  As described above, by providing the holding protrusion 33, the cartridge heater 6 is held by the holding protrusion 33 of the second insert 34, while the clearance between the second insert 34 and the cartridge heater 6 in the portion without the holding protrusion 33 is secured. By doing so, the extra heating other than the cavity surface 2 can be reduced and the amount of heat required for cooling can be suppressed. Therefore, the cooling efficiency of the mold can be improved, sufficient heating and cooling of the mold can be performed in a short time, and even if continuous molding production with a short molding tact is performed, the sink of the thick part of the resin and the mold There is no warp deformation after taking out, and a molded product can be obtained with good appearance quality.

  In the above description, the upper mold is composed of the first insert and the second insert, and the cartridge heater is provided at the boundary between the first insert and the second insert. Both of the lower molds may be constituted by a first insert and a second insert, and a cartridge heater may be provided at the boundary between the first insert and the second insert. Moreover, the injection mold may be composed of not only two of the lower mold and the upper mold but also three or more molds.

  In the above description, only one example has been shown. When the molding die according to the present invention and the molding method are applied, various exterior molded products can be continuously molded with high productivity in a short molding time. However, a molded product 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 for injection molding of the present invention, it is possible not only to obtain a molded product with good productivity and good appearance quality, but also to reduce the post-molding process after molding such as painting treatment. In addition to reducing resources such as paint, the resin member can be recycled.

  INDUSTRIAL APPLICABILITY The present invention can provide a molded product in a good state without impairing the appearance quality of an exterior molded product even when continuous molding production with a short molding tact is performed, and injection molding used for molding a resin molded product This is useful for metal molds and injection molding methods using the same.

DESCRIPTION OF SYMBOLS 1 Molding area 2 Cavity surface 3 First nesting 4 Second nesting 5 First nesting cooling circuit 6 Cartridge heater 7 First heat transfer range 8 Second heat transfer range 9 Mold opening / removing process 10 Mold closing process 11 Injection / holding pressure Process 12 Glass transition temperature 13 Cooling process 14 Second nesting flange surface 15 Second heat transfer range clearance 16 First heat transfer range clearance 17 Air heat insulation layer 18 Second nesting cooling circuit 19 Fixed side mold plate 20 Heat insulation plate 21 Second nesting Protrusion amount 22 First nesting amount 23 Thermal expansion difference 24 First nesting first heat propagation 25 First nesting second heat propagation 26 Second nesting first heat propagation 27 Minimum temperature rise point 28 Cartridge heater diameter 29 First nesting Heater holding radius 30 Second nested heater holding radius 31 Center of second nested heater holding radius 32 Cartry Die heater pressing point 33 Holding projection 34 Second insert 40 Injection mold 41 Upper mold 42 Lower mold 43 Groove 50 Cavity surface 51 Nesting front member 52 Nesting back member 53 Electric heater 54 Cooling circuit 55 Mold insertion Child 56 groove

Claims (8)

An injection mold formed of a plurality of molds and injecting resin into a molding region to form a molded product,
A first insert that is a component of the mold and is in contact with the molding region;
A groove formed in the first nest and spaced apart from the molding region;
A second insert that is inserted into the groove and forms one component of the mold;
A heater provided at a boundary between the first nesting and the second nesting;
A cooling circuit for cooling the mold;
A first heat transfer range of the first nesting for holding the heater;
A second heat transfer range of the second nested holding the heater, the heat conduction efficiency from the heater to the second heat transfer range is from the heater to the first heat transfer range An injection mold characterized by being smaller in heat conduction efficiency.   The injection mold according to claim 1, wherein the shortest distance from each of the heaters to the molding region is smaller than the shortest distance from each of the cooling circuits to the molding region.   3. The injection mold according to claim 1, wherein a thermal expansion coefficient of the first nesting material is smaller than a thermal expansion coefficient of the second nesting material.   The injection molding gold according to any one of claims 1 to 3, wherein a thermal conductivity of the first nesting material is larger than a thermal conductivity of the second nesting material. Type. The heater is cylindrical,
A cross-sectional shape of the first heat transfer range and the second heat transfer range is an arc shape,
A heater radius that is a radius of a cross-sectional circle of the heater, a first nested heater holding portion radius that is a radius of a cross-sectional shape of the first heat transfer range, and a second that is a radius of a cross-sectional shape of the second heat transfer range The relationship with the radius of the nested heater holder is
5. The injection mold according to claim 1, wherein the heating heater radius <the first nested heater holding portion radius <the second nested heater holding portion radius.   The injection mold according to any one of claims 1 to 5, wherein a protrusion is provided in the second heat transfer range of the second insert.   A flange surface is provided on the second insert, and when the second insert is inserted into the groove, the flange surface contacts the surface of the first insert, and a clearance is provided between the second insert and the heater. The injection mold according to any one of claims 1 to 6, wherein the mold is produced. Heating the injection mold according to any one of claims 1 to 7 using the heater;
Injecting a resin into the molding region of the injection mold;
Cooling the injection mold using the cooling circuit;
And a step of taking out the molded product.

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