JPH08290429A - Molding of resin molded product - Google Patents

Abstract

PURPOSE: To eliminate molding inferiority such as the curing irregularity, sink or dent caused by temp. irregularity by eliminating the temp. irregularity between the part in the vicinity of a place where a molding material is arranged or a place where the molding material is injected and other part. CONSTITUTION: In such a state that the temp. of either one of a lower mold 1 and an upper mold 2 is set higher than that of the other one of them, a molding material is arranged to the mold of which the temp. is set high. Thereafter, the temp. of the mold of which the temp. is set high is lowered to perform the temp. control of the molds so that both molds become uniform at the same temp. and the molding material is pressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a resin molded product with a split mold.

[0002]

2. Description of the Related Art Conventionally, a method of forming a resin molded product by using upper and lower molds has been known. For example, a thermosetting molding material such as BMC (Bulk Molding Compound) or SMC (Sheet Molding Compound) is installed in the center of the lower mold while the upper mold is raised and the mold is opened. Then, after that, the upper mold is lowered and pressed to perform molding. However, when the thermosetting molding material is installed in the lower mold of the split mold kept at a predetermined temperature, the temperature of the thermosetting molding material installed in the center of the lower mold is low, The temperature of the central portion, which is the installation portion of the molding material of the lower mold, becomes lower than that of the portion other than the installation portion of the molding material of the upper mold and the lower mold due to the installation of the molding material.
FIG. 12 is a graph showing that when the BMC is installed in the lower mold in the compression molding method, the temperature of the installation part of the BMC becomes lower than the set temperature of the lower mold. It can be seen that the installed part is lower than the set temperature of about 15 ° C lower mold. As a result, upon molding, there is a temperature variation between the lower die molding material installed portion, the lower die periphery and the upper die, and uneven curing occurs in the obtained molded product due to the temperature variation, Molded product defects such as sink marks and dents occurred.

On the other hand, Japanese Unexamined Utility Model Publication No. 64-27213 is known as one in which the temperature distribution of each part of the upper mold and the lower mold is made different. In this conventional example, a thermosetting molding material such as SMC is placed in the center of the lower mold in a state where the upper mold is raised and the mold is opened, and then the upper mold is lowered. It is designed to be pressed. Further, in the above-mentioned conventional example, the temperature of the lower mold is controlled so that the temperature of the central part of the lower mold is high and the temperature of the surroundings is low, and the upper mold has the same temperature distribution as the lower mold. Are controlled. However, in the case where the upper mold is controlled so that the temperature distribution is the same as that of the lower mold, only the installation position of the molding material of the lower mold has a temperature variation due to the temperature decreasing by the molding material. However, even in this conventional example, the installation position of the molding material of the lower mold and the other parts of the lower mold and the upper mold when the molding material is installed and molded in the lower mold. There was uneven curing due to temperature variations, and defects such as sink marks and dents occurred in the molded product.

Further, in injection molding of thermoplastic synthetic resin, when the molding material composed of the thermoplastic resin plasticized by the injection cylinder is supplied to the cavity through the sprue, runner and gate, the molding material is heated at high temperature and high speed. Since it is supplied to the cavity with heat, the mold wall surface near the gate heats up due to shearing, and the temperature becomes higher than the initially set temperature, causing temperature unevenness. There is a problem that uneven curing of the working material occurs and molding defects such as sink marks occur.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the above-mentioned conventional examples, and its object is to place the molding material or inject the molding material. Another object of the present invention is to provide a method for molding a resin molded product, which eliminates variation in temperature between the vicinity of a place and other portions and has no molding defects such as uneven curing, sink marks, and dents due to the variation in temperature.

[0006]

In order to solve the problems of the conventional examples described above and to achieve the object of the present invention, the method for molding a resin molded article of the present invention is either a lower mold 1 or an upper mold 2. With one temperature set higher than the other,
Place molding material 3 in the mold with the higher setting, then
Lower the temperature of the mold set higher and pressurize by controlling the temperature of the mold so that the temperature of the mold set higher becomes uniform at the same temperature as the temperature of the mold set lower. It is characterized by doing.

Further, one of the lower mold 1 and the upper mold 2 is used as the mold in which the molding material 3 is installed, and the molding material 3 of the mold in which the molding material 3 is installed is installed. While the temperature of the molding material 3 is higher than that of the other mold and the temperature of the portion other than the portion where the molding material 3 is installed is set to the same temperature as the mold in which the molding material 3 is not installed, the molding material 3 is The molding material 3 is installed in the mold in which the molding material 3 is installed, and then the temperature of the mold in which the molding material 3 is installed is uniform at the set temperature of the mold in which the molding material 3 is not installed. It is also preferable to control the temperature of the mold and pressurize the mold so that

The molding material 3 is injected into the cavity 5 through the gate 4 with the temperature of the vicinity of the gate 4 portion of the die set to be lower than that of the other portions.
After that, it is also preferable to control the temperature of the mold so that the vicinity of the gate 4 part of the mold becomes uniform at the same temperature as the other parts.

[0009]

According to the present invention of the method as described above, the molding material 3 is set high while the temperature of either the lower mold 1 or the upper mold 2 is set higher than the temperature of the other. Place it on the other mold and then lower the temperature of the higher mold to make the temperature of the higher mold uniform at the same temperature as the temperature of the lower mold. By controlling the temperature of the mold and applying pressure, the molding material 3 such as BMC or SMC is placed in one of the molds, and the molding material 3 is installed even if the temperature of the mold is lowered. Since the mold on which the molding material 3 is installed is set to a higher temperature than the mold on which the molding material 3 is not installed, the temperature of the part on which the molding material 3 is installed is lowered by the temperature of the molding material 3. The mold temperature can be brought close to the set temperature of the mold, and therefore, the molding material 3 is set thereafter. It is possible to easily control the temperature of the mold to be the same as the set temperature of the mold for which the molding material 3 is not installed, and prevent molding defects such as uneven curing, sink marks, and dents due to temperature variations. It can be done.

Further, one of the lower mold 1 and the upper mold 2 is set as the mold on which the molding material 3 is installed, and the molding material 3 of the mold on which the molding material 3 is installed is installed. While the temperature of the part to be molded is higher than that of the other mold, and the temperature of the part other than the part where the molding material 3 is installed is set to the same temperature as the mold where the molding material 3 is not installed, the molding material 3 is The molding material 3 is installed in the mold in which the molding material 3 is installed, and then the temperature of the mold in which the molding material 3 is installed is uniform at the set temperature of the mold in which the molding material 3 is not installed. By controlling the temperature of the mold so as to achieve the pressurization, the temperature of the part where the molding material 3 of one mold is installed is lowered by the installation of the molding material 3, whereby the molding material 3 The temperature of the mold where the molding material is installed is the same as the set temperature of the mold where the molding material 3 is not installed. Can do easy to control so that the temperature, in which temperature molding defects such as curing unevenness and sink marks or dents due to the variation in can be prevented from occurring.

The molding material 3 is injected into the cavity 5 through the gate 4 with the temperature of the vicinity of the gate 4 portion of the mold set to be lower than that of other portions.
After that, in the case where the temperature of the mold is controlled so that the vicinity of the gate 4 part of the mold becomes uniform at the same temperature as the other parts, the molding material 3 made of thermoplastic synthetic resin is passed through the gate 4 and the cavity When the molding material 3 passes through the vicinity of the gate 4 when it is supplied into the mold 5, shearing heat is generated on the mold wall surface in the vicinity of the gate 4 and the temperature becomes higher than the initially set temperature, resulting in uneven temperature. By injecting the molding material 3 into the cavity 5 through the gate 4 in a state where the temperature in the vicinity of the gate 4 portion of the mold is set to be lower than that in other portions, the occurrence of the temperature unevenness is suppressed, The temperature of the mold can be easily controlled so that the vicinity of the gate 4 part of the mold is uniform at the same temperature as the other parts, and the curing balance of the molding material 3 supplied into the cavity 5 is controlled. By doing , In which it is possible to eliminate the molded article defective.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the first embodiment shown in the accompanying drawings. 1 to 4 show one embodiment of the present invention. A split mold for molding a resin molded product is composed of a lower mold 1 and an upper mold 2. In the illustrated embodiment, the lower mold 1 is concave and the upper mold 2 is convex. Lower mold 1, upper mold 2
First temperature control means 6 for controlling the surface temperature of the mold is provided over the entire area. Further, a portion other than the molding material installation portion 9 which is a portion where the molding material 3 of the lower mold 1 is installed (in the illustrated embodiment, the central portion of the lower mold 1 is a portion where the molding material 3 is installed). , The outer periphery of the lower mold 1 is a portion where the molding material 3 is not installed)
Temperature control means 7 is provided. Here, the first temperature control means 6 is a heater, a steam pipe or the like for keeping the mold temperature at a predetermined temperature, and the second temperature control means 7 is a cooling pipe for lowering the mold temperature. Is.

Molding of a resin molded product using the mold having the above structure is performed by the steps shown in FIGS. The molding material 3 used in this example is B
MC (bulk molding compound) and SM
It is a thermosetting resin molding material such as C (sheet, molding, compound). The numbers of the control temperatures of the first temperature control means 6 and the second temperature control means 7 shown in the following examples are the same as those of the lower mold 1 such as BMC which is the molding material 3.
In the case where it is known that the temperature of the molding material installation portion 9 of the lower mold 1 is lower than the set temperature of the lower mold 1 by 15 ° C. when the is installed, it is described as an example of the numerical value of the control temperature. Therefore, the present invention is not necessarily limited to just this controlled temperature number.

First, in the first step shown in FIG. 1, the upper mold 2 is heated to 120 ° C. by the first temperature control means 6 and the lower mold 1 is used.
Is raised by the first temperature control means 6 to 135 ° C. Next, in the first step shown in FIG. 1, after the upper mold 2 and the lower mold 1 reach predetermined temperatures, respectively, as shown in FIG.
The BM which is the molding material 3 in the molding material installation portion 9 of the lower mold 1.
C is installed (2nd process). At this time, in the case of BMC, the temperature of the molding material 3 is about 25 ° C. Therefore, the molding material installation part 9 which is the part where the molding material 3 of the lower mold 1 is installed.
Temperature drops to about 120 ° C. However, although the temperature drops except for the molding material installation portion 9 of the lower mold 1, 12
It does not reach 0 ° C but reaches 130 ° C. Therefore, lower mold 1
In order to eliminate the temperature unevenness, the second temperature control means 7 does not install the molding material 3 of the lower mold 1 at the same time as the molding material 3 is installed in the lower mold 1 in the second step shown in FIG. The temperature of the peripheral part of the lower mold 1 is set to 120 ° C.

Next, as shown in FIG. 3, the upper mold 2 is lowered to compression-mold the molding material 3. In the third step shown in FIG. 3, the first mold provided on the upper mold 2 and the lower mold 1 is processed. The temperature control means 6 is controlled so that the mold temperature is maintained at 120 ° C.
Further, the second temperature control means 7 has a peripheral portion of the lower mold 1 having a temperature of 12
It turns off when it reaches 0 ° C. Next, after performing compression molding for a predetermined time in which the molding material 3 is completely cured and becomes a resin molded product, the upper mold 2 is raised and the mold is opened as shown in FIG. 4 (fourth step). . After that, the resin molded product 10 is taken out from the opened mold (fifth step), and the state shown in FIG. 1 is obtained again.

Another embodiment of the present invention will be described with reference to FIGS. In this embodiment, a split mold for molding a resin molded product is composed of a lower mold 1 and an upper mold 2. In the illustrated embodiment, the lower mold 1 is a concave mold and the upper mold 2 is a convex mold. Has become. Each of the lower mold 1 and the upper mold 2 is provided with a first temperature control means 6 for controlling the surface temperature of the mold, and is a portion where the molding material 3 of the lower mold 1 is placed. The second temperature control means 7 is provided in the molding material installation portion 9 portion (in the illustrated embodiment, the central portion of the lower mold 1 is the portion for installing the molding material 3). Here, the first temperature control means 6 is a heater, a steam pipe or the like for keeping the mold temperature at a predetermined temperature, and the second temperature control means 7 is a heater, a steam pipe for raising the mold temperature. Etc.

Molding of a resin molded product using the mold having the above-mentioned structure is carried out by the steps shown in FIGS. The molding material 3 used in this example is B
MC (bulk molding compound) and SM
It is a thermosetting resin molding material such as C (sheet, molding, compound). The numbers of the control temperatures of the first temperature control means 6 and the second temperature control means 7 shown in the following examples are the same as those of the lower mold 1 such as BMC which is the molding material 3.
In the case where it is known that the temperature of the molding material installation portion 9 of the lower mold 1 is lower than the set temperature of the lower mold 1 by 15 ° C. when it is installed, it is explained as an example of the numerical value of the control temperature. Therefore, the present invention is not necessarily limited to just this controlled temperature number.

First, in the first step shown in FIG. 5, the temperature of the upper mold 2 and the lower mold 1 is raised by the first temperature control means 6 to 120 ° C., and the lower mold 1 is molded. Material 3
The temperature of the portion where is installed is set to 135 ° C. in advance by the second temperature control means 7. Next, in the first step shown in FIG. 5, after the upper mold 2 and the lower mold 1 have reached the respective predetermined temperatures, as shown in FIG.
The molding material 3 made of is set (second step).

Next, in the third step, as shown in FIG.
And the molding material 3 is compression molded. The first temperature control means 6 provided in the upper mold 2 and the lower mold 1 in the third step shown in FIG. 7 keeps the mold temperature at 120 ° C. Controlled as. The second temperature control means 7 is turned off when the temperature of the molding material installation portion 9 of the lower mold 1 reaches 120 ° C, or is controlled to 120 ° C. Next, molding material 3
After carrying out compression molding for a predetermined time to completely cure and become a resin molded product, the upper mold 2 is raised and the mold is opened as shown in FIG. 8 (fourth step). In this fourth step, each of the first temperature control means 6 provided on the upper mold 2 and the lower mold 1 has 120
The second temperature control means 6 is turned off or 120
Controlled to ℃. Thereafter, the resin molded product 10 is taken out from the opened mold (fifth step), and again in the state of FIG. 5 (that is, the first temperature control means 6 is controlled to 120 ° C.,
Temperature control means 7 is controlled to 135 ° C.).

In the above description of each embodiment, the molding material 3 is installed in the lower mold 1, but the molding material 3 may be replaced in the upper mold 2. Still another embodiment of the present invention will be described with reference to FIGS. In this embodiment, the split mold is an injection mold and the molding material 3 is a thermoplastic synthetic resin. That is, the split mold is composed of a movable mold 20 and a fixed mold 21, and a molding material 3 made of a thermoplastic synthetic resin such as plasticized ABS resin is sprued by an injection cylinder (not shown) 22. Runner 23, gate 4
And is supplied to the cavity 5 via. In the figure, 25 is a movable side mounting plate to which the movable die 20 is fixed,
Reference numeral 26 is a fixed side mounting plate to which the fixed mold 21 is mounted, and 24 is an ejector pin. The movable mold 20 and the fixed mold 21 are each provided with a first temperature control means 6,
A second temperature control means 7 is provided near the gate 4 of the fixed mold 21 to the movable mold 20. Here, in the embodiment, the second temperature control means 7 is provided only near the gate 4 only in the fixed die 21, but the second temperature control means 7 may be provided only near the gate 4 only in the movable die 20. Further, the second temperature control means 7 may be provided near each gate 4 of the movable die 20 and the fixed die 21. In this embodiment, the first temperature control means 6 is a cooling pipe and the second temperature control means 7 is also a cooling pipe.

Molding of a resin molded product using the mold having the above-mentioned structure is carried out by the steps shown in FIGS. First, in the first step shown in FIG.
The temperature of the mold composed of the movable mold 20 and the fixed mold 21 is maintained at 60 ° C. by the temperature control means 6 of FIG. In this case, the mold temperature is maintained at 60 ° C. by causing water to flow at a constant speed through the cooling pipe that constitutes the first temperature control means 6. At this time, the second temperature control means 7 arranged near the gate 4 moves the mold to 60.degree.
(The mold temperature is maintained at 60 ° C. by causing water to flow at a constant speed through the cooling pipe forming the second temperature control means 7).

Next, as shown in FIG. 10, before the molding material 3 made of a thermoplastic synthetic resin such as plasticized ABS resin is injected from the injection cylinder, the second temperature control means 7 is used. The temperature is controlled so that the temperature in the vicinity of the gate 4 is low (50 ° C.), and the other parts of the mold are controlled to 60 ° C. by the first temperature control means 6 (second step). in this case,
It is possible to make the temperature lower than that of the first temperature control means 7 by increasing the flow rate of water flowing through the cooling pipe forming the second temperature control means 7. In this state, the molding material 3 is injected from the injection cylinder as shown in FIG.
Molding material 3 is sprue 22, runner 23, gate 4
And then injected into the cavity 5 (third step). The second temperature control means 7 is controlled to the same temperature as the first temperature control means 6 so as to keep the mold temperature constant during the filling of the molding material 3 into the cavity 5 of FIG. When the molding is completed, the movable mold 20 is moved to open the mold, the resin molded product is taken out (fourth step), and then the first mold shown in FIG.
It returns to the process.

In the above embodiment, in the first step shown in FIG. 9, as described above, the second temperature control means 7 sets the mold having the same temperature as the temperature control by the first temperature control means 6 to 60 ° C.
Although the example in which the temperature is controlled so as to be maintained is shown, the gate 4 of the mold is controlled by the second temperature control means 7 from the time of the first step.
It may be controlled so that the vicinity thereof has a low temperature (50 ° C.).

By the way, in injection molding, when the molding material 3 made of a thermoplastic resin plasticized by the injection cylinder is supplied to the cavity 5 through the sprue 22, the runner 23 and the gate 4, the molding material 3 is Since it is supplied to the cavity 5 at high temperature and high speed, the mold wall surface in the vicinity of the gate 4 generates shear heat and becomes higher than the initially set temperature, resulting in temperature unevenness. Uneven curing of the supplied molding material 3 occurs, which causes a defective molding phenomenon such as sink marks. However, as in the present embodiment, the temperature in the vicinity of the gate 4 portion of the mold becomes lower than that in other portions. Since the molding material 3 is injected into the cavity 5 through the gate 4 in such a state that even if the wall surface of the mold is sheared and generates heat in the vicinity of the gate 4, the temperature unevenness of the entire mold is eliminated. After the filling with the molding material 3, by controlling the temperature of the mold so that the vicinity of the gate 4 of the mold becomes uniform at the same temperature as the other parts, a molding defect due to the uneven temperature of the mold is caused. Can be prevented.

[0025]

According to the first aspect of the present invention, the molding material is set high while the temperature of either the lower mold or the upper mold is set higher than the temperature of the other mold. The mold set higher, then lower the temperature of the mold set higher so that the temperature of the mold set higher becomes uniform at the same temperature as the temperature of the mold set lower. Since the temperature of the mold is controlled and pressure is applied, there is no variation in temperature between the place where the molding material is installed and other parts, and uneven curing, sink marks or dents due to the variation in temperature due to the installation of the molding material. It is possible to form a resin molded product without molding defects such as.

According to the second aspect of the present invention, either the lower mold or the upper mold is the mold in which the molding material is installed, and the mold in which the molding material is installed is In a state in which the temperature of the part where the molding material is installed is higher than that of the other mold and the temperature of the part other than the part where the molding material is installed is set to the same temperature as the mold in which the molding material is not installed,
The molding material is installed in the mold in which the molding material is installed, and then the temperature of the mold in which the molding material is installed is the same as the set temperature of the mold in which the molding material is not installed. Since the temperature of the mold is controlled and pressure is applied so that it is uniform, it is possible to form a resin molded product that does not have molding defects such as uneven curing, sink marks, and dents due to temperature variations due to the installation of molding material. is there.

According to the third aspect of the present invention, the molding material is set in the cavity through the gate in a state where the temperature in the vicinity of the gate portion of the mold is set to be lower than that in other portions. After injecting, the mold temperature is controlled so that the vicinity of the gate part of the mold becomes uniform at the same temperature as the other parts, so control the curing balance of the molding material supplied into the cavity. It is possible to eliminate defects in molded products.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a molding sequence of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a molding sequence of the same.

FIG. 3 is a cross-sectional view showing a molding sequence of the above.

FIG. 4 is a cross-sectional view showing a molding sequence of the same.

FIG. 5 is a sectional view showing a molding sequence of another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing the same molding sequence as above.

FIG. 7 is a cross-sectional view showing the same molding sequence as above.

FIG. 8 is a cross-sectional view showing the molding sequence of the above.

FIG. 9 is a cross-sectional view showing a molding sequence of still another embodiment of the present invention.

FIG. 10 is a cross-sectional view showing the molding sequence of the above.

FIG. 11 is a cross-sectional view showing the molding sequence of the above.

FIG. 12 is a graph showing that the temperature of the material installation portion decreases when the molding material is installed in the lower mold.

[Explanation of symbols]

 1 Lower mold 2 Upper mold 3 Molding material 4 Gate 5 Cavity

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masunori Kobayakawa 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Masami Matsumoto, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works Co., Ltd.

Claims (3)

[Claims] 1. A method in which one of the lower mold and the upper mold is set to a temperature higher than the other temperature, and the molding material is placed in the mold set higher, and then the mold is set higher. The temperature of the mold is lowered so that the temperature of the mold set higher is uniform at the same temperature as the temperature of the mold set lower, and pressure is applied by controlling the temperature of the mold. Molding method for resin molded products. 2. The lower mold or the upper mold is used as a mold in which the molding material is installed, and the temperature of a portion of the mold in which the molding material is installed is set. A method in which the molding material is installed while the temperature is higher than that of the other mold and the temperature other than the portion where the molding material is installed is set to the same temperature as the mold in which the molding material is not installed. After that, the temperature of the mold is controlled so that the temperature of the mold where the molding material is installed becomes uniform at the same temperature as the set temperature of the mold where the molding material is not installed. A method for molding a resin molded product, which comprises applying pressure. 3. A molding material is injected into a cavity through a gate in a state where a temperature near a gate portion of the die is set to be lower than that of other portions, and then the gate portion of the die is injected. A method for molding a resin molded product, characterized in that the temperature of a mold is controlled so that the vicinity is uniform at the same temperature as the other portions.