JPS62117716A - Mold and temperature controlling thereof - Google Patents

Abstract

PURPOSE:To uniformize the temperature of a mold as a whole and consequently effectively cool molten resin in a short period of time by a method wherein a large amount of hot water, the temperature of which is nearly equal to the removal temperature of a molded part, as cooling medium is circulated through a mold consisting of a movable mold core and a fixed mold core, both of which are made of material with high heat conductivity. CONSTITUTION:In a movable mold core 13, the hot water supplied through a pipe 57 is circulated through holes 24, 18, 28, 18, 30, 18, 32, 18 and 26 in the order named. On the other hand, in a fixed mold core 14, the hot water fed to a hole 60 is circulated through holes 61, 62, 63, 64 and 65 in the order named and discharged outside from the fixed mold core 14. Because the movable mold core 13 and the fixed mold core 14 are made of material with high heat conductivity in the case, the mold temperature of the movable mold core 13 and of the fixed mold core 14 are uniformized as a whole. In addition, because the cooling medium channel formed in the movable mold core 13 is so constituted as to be made square with that formed in the fixed mold core 14, uniform cooling effect is given to a molded part formed by a cavity 16.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold and a method for controlling its temperature, and more particularly, the present invention relates to a mold used for plastic molding, in particular, the cavity portion of the mold is formed of a member with excellent thermal conductivity, and By flowing a large amount of cooling medium, such as hot water or hot oil, set at the temperature for taking out the molded product into the mold, the difference in cooling temperature of the molded product is reduced, cooling efficiency is increased, and the molding cycle is shortened. Moreover, it relates to a mold and its temperature control N (1 method) that achieves further improvement in the quality of molded products.

When a molded product made of synthetic resin is obtained by injection molding,
A heated and molten resin material is injected under high pressure into a cavity defined by a mold consisting of a fixed mold and a movable mold, and after the molten resin is cooled and solidified, the fixed mold and the movable mold are separated, A so-called mold opening is performed and a molded product of a predetermined shape is taken out.

Therefore, it is essential to speed up the cooling rate of the molten resin in the mold and open the mold early in order to shorten the molding cycle time.

Therefore, normally, a channel for a cooling medium is formed in advance inside the mold, and the molten resin is forcibly cooled from outside the cavity by, for example, passing cooling water as a coolant through this channel. ing.

However, in general, molds are made of steel, which has relatively poor thermal conductivity as a metal, and the diameter of the flow passage formed inside the mold is relatively small considering the overall dimensions of the mold. is extremely small. Furthermore, cooling water at a temperature below normal is passed through such a flow path.

In such a case, forced cooling of the molten resin must be performed through a member with low thermal conductivity that constitutes the mold. Moreover, since the flow path has a small diameter, it is impossible to flow a large amount of cooling water at once, and as a result, the molten resin in the cavity cannot be efficiently cooled.

Further, as described above, since the mold constituent members have low thermal conductivity, the cooling temperature difference becomes large in some parts, and therefore, the surface temperature of the part defining the cavity is not uniform. As a result, the entire molten resin cannot be cooled uniformly, which may generate internal stress in the molded product, leading to quality defects such as shrinkage or distortion.

The present invention has been made in order to overcome the above-mentioned disadvantages, and in particular, the cavity defining portion of the mold is formed of a material with high thermal conductivity, and water or oil, etc., set at the temperature for taking out the molded product, etc. By circulating the cooling medium widely through the flow path, cooling efficiency is improved, thereby shortening the molding cycle time and making it possible to manufacture molded products with stable quality. The purpose of the present invention is to provide a mold and a method for controlling its temperature.

To achieve the above object, the present invention provides a mold consisting of a movable mold and a fixed mold for molding a molded product by cooling and solidifying a supplied molten material, wherein the movable mold has a movable mold main body and the movable mold body. The fixed mold includes a movable mold insert integrated into the mold body, while the fixed mold includes a fixed mold main body and a fixed mold insert integrated with the fixed mold body, and the movable mold insert and the fixed mold insert The movable mold insert and the fixed mold insert are each made of a member having a higher thermal conductivity than the movable mold main body and the fixed mold main body, and It is characterized in that a cooling medium is made to flow through each of the mold insert and the fixed mold insert to define a coolant flow path for forcibly cooling the molten material.

Furthermore, the present invention also provides a movable insert made of a member that is integrated with a movable main body and has a higher thermal conductivity than the movable main body, and a movable insert that is integrated with a fixed main body and has a higher thermal conductivity than the fixed main body. A cavity for the molded article is defined by clamping together a fixed mold insert made of a material with a high ratio of molding, pouring molten material into the cavity, and then separating the movable mold body from the fixed mold body. The molds of the movable mold insert and the fixed mold insert are opened, and the molded product solidified within the cavity is taken out. During this time, the cooling medium flow channels formed in the movable mold insert and the fixed mold insert The method is characterized in that the molten material in the cavity is forcibly cooled and solidified by passing a cooling medium set to approximately the temperature at which the molded product is taken out.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of the mold temperature control method according to the present invention will be described in detail with reference to the accompanying drawings, in connection with a mold for implementing the method.

In FIG. 1, reference numeral 10 indicates a mold according to the present invention, and the mold 10 substantially consists of a movable mold 11 and a fixed mold 12. In this case, the movable mold 11 and the fixed mold 12 include a movable mold insert 13 and a fixed mold insert 14 which define a cavity 16 for molding a molded product by coming into contact with each other. The movable insert 13 and the fixed insert 14 are made of a material with high thermal conductivity, such as pure copper, copper alloy, aluminum, aluminum alloy, or zinc alloy.

A hole 18 is formed in the movable insert 13 and extends through the hole 18 in the horizontal direction in the figure.Plug members 20 and 22 are fitted into both ends of the hole 18 to close the hole 18. The opening is sealed.

In this case, the diameter of the hole 18 is selected to be larger than the refrigerant flow path in a conventional mold of approximately the same size.

Further, from the side surface of the movable insert 13 to the i of the hole 18,
A hole 24 is bored in communication with the end, and similarly, a hole 18
A hole 26 is bored in communication with the other end (see FIG. 2). Inner screws 24a and 26a for connecting a tube body, which will be described later, are cut into the openings of the side surfaces of the movable insert 13 in the holes 24 and 26. Additionally, holes 28, 30 and 32 are defined spaced apart from each other in communication with the hole 18 and directed toward the cavity 16. In addition, as can be easily understood from the figure, this hole 28.30.3
The deepest parts of No. 2 are formed so as to be sharpened. In this case, the diameter of the bore 28, 30, 32 is selected to be larger than that of the bore 18.

Next, a plug member 36 is fitted into the portion where the hole 28 opens at the bottom of the movable insert 13, and a partition plate 34 facing the hole 28 is implanted in the plug member 36. Therefore, it can be understood that by separating the tip of the partition plate 34 from the part that defines the deepest part of the hole 28, an inverted U-shaped flow path is defined within the hole 28. . Similarly, the opening of the hole 30 is closed by a plug member 40 to which a partition plate 38 is fixed, and the opening of the hole 32 is closed by a plug member 44 to which a partition plate 42 is fixed.

That is, an inverted U-shaped flow path is defined in each of the holes 28, 30, and 32, and by allowing the refrigerant to flow through this flow path, it is possible to further enhance the cooling effect on the movable insert 13 side. becomes.

The movable insert 13 configured as described above is attached to the movable main body 46. That is, a recess 48 is formed in the movable main body 46, and as shown in FIG. 2, holes 50 and 52 having a relatively large diameter are connected to the recess 48.
is drilled. Therefore, when attaching the movable insert 13 to the movable main body 46, a heat insulating material 54 is interposed between the movable main body 46 and the movable insert 13, and the movable insert 13 is inserted into the recess. 48. The heat insulating material 54 is preferably made of stainless steel, asbestos, synthetic resin, or the like, which has a heat insulating effect.Furthermore,
As shown in FIG. 1, bolts 56a and 56b are inserted into the movable mold insert 13, the heat insulating material 54, and the movable mold main body 46 through predetermined holes from the movable mold main body 46 to the movable mold insert 13. Insert the movable mold insert 13, the heat insulating material 54, the movable mold main body 4
Tighten 6. The holes 50 and 52 formed in the movable mold main body 46 are configured to communicate with the holes 24 and 26 formed in the movable mold insert 13, as shown in FIG. .

Therefore, in this way, the holes 50 and 24 and the holes 52 and 2
In order to communicate with each other, required holes are bored in the heat insulating material 54. A pipe body 5 constituting a refrigerant pipe line
7 is inserted into the hole 50, and the thin tip of the tube 57 is screwed onto the internal thread 24a of the hole 24 to connect the flow path. Similarly, a tube 59 is inserted into the hole 52 and its tip is connected to the internal thread 26a of the hole 26.

Next, the movable main body 46 is mounted on a base 58. Further, the base 58 is connected to an actuator (not shown) and is configured to be movable in the vertical direction in the figure.

On the other hand, the fixed mold insert 14, which is fixed at a predetermined position, has holes 60 to 65, which are selected to have a relatively larger diameter than the flow path in a conventional mold of the same size, and are separated from the cavity 16 by a predetermined distance. The holes are drilled parallel to each other. As can be easily seen from FIG. 1, the holes 60 to 65 extend perpendicularly to the holes 18, 28, 30 and 32 defined in the movable insert 13, respectively. Also, cavity 1
A molten metal supply channel 68 is bored in the fixed mold insert 14 so as to communicate with the molten metal supply channel 6 .

The fixed mold insert 14 configured as described above is fixed to the fixed mold main body 72 via the heat insulating material 70. The method of integrating the fixed mold insert 14, the heat insulating material 70, and the fixed mold main body 72 is the same as the method of integrating the movable mold insert 13, the heat insulating material 54, and the movable mold main body 46, that is, the fixed mold main body The fixed mold insert 14 is fitted into the recess 74 formed in the fixed mold insert 14 via the heat insulating material 70, and the bolts 76 to 79 are inserted from the fixed mold main body 72 to the fixed mold insert 14 as shown in the figure. and tighten it. Further, the heat insulating material 70 and the fixed main body 72 are provided with holes (not shown) that communicate with the holes 60 to 65, and a predetermined pipe body is inserted into the hole and connected to the holes 60 to 65. By doing so, as shown in FIG.
61-62-63-64-65 and a flow path through which the refrigerant flows is configured.

A bushing member 82 is inserted into the upper surface of the fixed mold main body 72, and this bushing member 82 is fitted into a hole 84 formed in the fixed mold insert 14. In this case, a sprue 86 formed within the bushing member 82 communicates with the molten metal supply channel 68. A plate member 88 is fixed to the upper surface of the fixed main body 72, and a locate ring 92 is fitted onto the plate member 88. A nozzle member 94 is inserted through the locate ring 92 , and a jet port of the nozzle member 94 is configured to communicate with the sprue 86 .

In addition, in the mold IO, it is more preferable if the movable mold 11 is provided with a protrusion mechanism for separating the molded product from the movable mold insert 13.

The mold according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, as shown by arrow E in FIG.
A large amount of hot water is continuously supplied to the hole 24 through the hole 24, and at the same time, as shown by the arrow F in FIG.
Similarly, a large amount of hot water is continuously supplied to 0. in this case,
The temperature of the hot water is set so that the temperatures of the movable mold insert 13 and the fixed mold insert 14 are within a temperature range at which the molten resin injected into the cavity 16 can be solidified.

In other words, the temperature of the hot water should be selected depending on the properties of the resin, but in terms of -C, if hot water is used at a temperature of about 30°C to 100°C, which is the temperature at which the molded product is taken out, the molten resin will be It can solidify suitably and ensure good quality. Furthermore, since the diameter of the flow path formed by drilling a plurality of holes inside the movable insert 13 and the fixed insert 14 is selected to be relatively large, a large amount of hot water can be continuously supplied. It is now possible to supply

In this case, in the movable insert 13, the hot water supplied through the pipe body 57 is
-18-32-18-26. At that time, hole 2
At 8.30.32, hot water flows through an inverted U-shaped channel, as shown in FIG. Note that the hot water flowing out from the hole 26 through the pipe 59 as shown by arrow G (see Fig. 2) is refluxed into a tank (not shown), and the temperature of this refluxed hot water is adjusted before being poured again. Hole 2 via pipe 57
It is preferable to configure a recirculation flow path so as to supply water to water 4, as this will reduce the amount of water used.

In addition, in the fixed insert 14, the hot water supplied to the holes 60 flows through the holes 61-62-63-64-65,
As shown by arrow H in FIG. 3, it flows out from the fixed mold insert 14. After the temperature of this hot water flowing outside is adjusted in the same manner as in the above case, it is recirculated to the flow path within the fixed insert 14. Furthermore, in this case, it is also possible to configure the hot water to flow through the channels inside the movable insert 13 and the fixed insert 14 to flow through one continuous circulation channel. can be easily understood.

Therefore, a large amount of hot water flows inside the movable insert 13 and the fixed insert 14, and since the movable insert 13 and the fixed insert 14 are made of a material with high thermal conductivity. The mold temperatures of the movable insert 13 and the fixed insert 14 are uniform throughout.

In addition, in this way, the cooling water as a refrigerant is used in the movable insert 1.
3 and the refrigerant flow path defined in the fixed mold insert 14, but as described above, the refrigerant flow path formed in the movable mold insert 13 and the refrigerant flow path formed in the fixed mold insert 14 Since the refrigerant channels are configured to be perpendicular to each other, it is possible to impart a uniform cooling effect to the molded product formed by the cavity 16.

Next, as shown by arrow I in FIG. 1, the heated and melted resin is press-fitted into the sprue 86 and the molten metal supply path 68 through the nozzle member 94. The temperature of the molten resin in such a case is variously selected depending on the type of resin, etc., but is generally 20°C.
The temperature ranges from around 0°C to 300°C or less. Therefore, the cavity 16 is filled with the molten resin press-fitted through the nozzle member 94, the sprue 86, and the molten metal supply path 68. At that time, the movable mold insert 13 and the fixed mold insert 14 were appropriately warmed with hot water set at the temperature for taking out the molded product.

In this state, the molten resin that reached the cavity 16 first is not cooled more rapidly than necessary. Therefore, the fluidity of the molten resin within the cavity 16 is good, and the operation of directly introducing the molten resin into the cavity 16 can be achieved reliably and easily.

In this way, the molten resin filled in the cavity 16 is cooled by the movable mold insert 13 and the fixed mold insert 14, which are kept at a suitable temperature by hot water. In this case, since the movable insert 13 and the fixed insert 14 have high thermal conductivity, the molten resin is uniformly cooled, and therefore,
No internal stress remains in the resin that solidifies in the cavity 16 to form a molded product, and no distortion or cracks occur.

After the molten resin is cooled and solidified, an actuator (not shown) connected to the base 58 is driven to displace the movable mold 11 in the direction of arrow B to open the mold and take out the solidified molded product.

After removing the molded product, the mold 10 is placed on standby again for the next molding process. That is, by driving the actuator, the movable mold 11 is displaced in the direction of arrow A to obtain a mold clamping state as shown in FIG. 1, and then the filling operation of the molten resin into the cavity 16 is performed again. In other words, new molded products can be obtained. Even when the injection molding operation is continuously repeated in this way, a large amount of hot water flows through the movable mold insert 13 and the fixed mold insert 14, and moreover, the movable mold insert 13 and the fixed mold insert Since the mold insert 14 itself has extremely good thermal conductivity, the heat transferred from the molten resin is exchanged with hot water as a cooling medium. Therefore,
It is possible to repeat suitable injection molding operations without the movable mold insert 13 and the fixed mold insert 14 reaching a predetermined temperature or higher.

Note that a heat insulating material 54 is interposed between the movable insert 13 and the movable main body 46, and the fixed insert 14 and the fixed main body 7 are further interposed.
2, a large amount of heat from the molten resin is not transferred to the movable mold body 46 and the fixed mold body 72, and as a result, the outer surface of the mold 10 does not reach abnormally high temperatures.

According to the present invention, as described above, the mold consisting of the movable mold insert and the fixed mold insert that define the cavity is formed of a material with high thermal conductivity, and the temperature at which the molded product is taken out is maintained within the mold. A large amount of hot water of approximately the same temperature is passed through as a cooling medium. Therefore, the temperature of the mold becomes uniform throughout, and the molten resin filled in the cavity defined within the mold is effectively cooled in a relatively short time by this large amount of cooling medium. Furthermore, since the cooling effect on the molten resin is uniformly performed, it is possible to further improve the quality of the molded product, and the rate of defects can be reduced.

Furthermore, as described above, since the mold has high thermal conductivity, the mold can be brought to an appropriate temperature in a short time by changing the temperature of the cooling medium passed through the mold. Therefore, even when the molding process is performed intermittently, it is possible to easily set the initial temperature of the mold, and molded products of stable quality can be manufactured from the beginning. Furthermore, since the cooling medium that is passed through the mold is hot water, the molten resin is not cooled more rapidly than necessary, and as a result, the flow resistance of the molten resin at the gate and inside the cavity is low. Even if the injection pressure is lowered to some extent, it is possible to spread the molten resin throughout the cavity, resulting in a high-quality molded product. As described above, the mold and its temperature control method according to the present invention can achieve various effects such as shortening the molding cycle time and improving the quality of molded products.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments. For example, fluids such as oil other than water may be used as the cooling medium. Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is a partial longitudinal cross-sectional view of a mold according to the present invention, FIG. 2 is a cross-sectional view taken along the line nn in FIG. 1, and FIG. It is an explanatory view shown in a top view.

Claims (4)

[Claims] (1) In a mold consisting of a movable mold and a fixed mold for molding a molded product by cooling and solidifying supplied molten material, the movable mold is a movable mold main body and a movable mold integrated with the movable mold main body. The fixed mold includes a fixed mold main body and a fixed mold insert integrated with the fixed mold main body, and a cavity in which a molded product is formed by the movable mold insert and the fixed mold insert. The movable insert and the fixed insert are respectively constructed of a member having a higher thermal conductivity than the movable main body and the fixed main body, and further, the movable insert and the fixed insert are A mold characterized in that a cooling medium is formed in each of the molds to forcibly cool a molten material by passing a cooling medium therethrough. (2) In the mold according to claim 1, a first heat insulating material is interposed between the movable mold insert and the movable mold body, and the first heat insulating material is interposed between the fixed mold insert and the fixed mold body. A mold in which a second heat insulating material is interposed. (3) A movable insert made of a member that is integrated with the movable body and has a higher thermal conductivity than the movable body, and a movable insert that is integrated with the fixed body and has a higher thermal conductivity than the fixed body. A cavity for the molded product is defined by clamping the fixed mold insert consisting of the members to each other, a molten material is poured into the cavity, and then the movable mold body is separated from the fixed mold body. The mold is opened between the insert and the fixed insert, and the molded product that has solidified inside the cavity is taken out.
During this time, the molten material in the cavity is forcibly cooled by passing a cooling medium set to approximately the temperature for taking out the molded product through cooling medium channels formed in each of the movable mold insert and the fixed mold insert. A mold temperature control method characterized by solidification. (4) In the method according to claim 3, the cooling medium is made of water or oil, and the water or oil is heated to a temperature of 30°C to 100°C, which is the temperature for taking out the molded product, and the cooling medium flow path is Temperature control method for molds supplied to