JP7552505B2 - Release agent spraying device and release agent spraying method - Google Patents

Description

This disclosure relates to a release agent spraying device and a release agent spraying method.

It is known that a release agent is sprayed onto the surface that defines the cavity, which is the molding part of the mold, to facilitate the release of the molded product. When a product is molded using a mold, the mold is at a high temperature, so even if a release agent is sprayed onto the surface that defines the cavity, the Leidenfrost phenomenon may occur, making it difficult for the release agent to adhere. Patent Document 1 describes a technique in which the release agent is sprayed in multiple batches. This allows the mold to be cooled by the release agent sprayed initially, improving the adhesion rate of the release agent.

JP 2005-7420 A

However, when cooling a mold with a liquid mold release agent, the surface of the mold and the area from the surface to a certain depth are cooled rapidly, causing a large difference in the amount of thermal expansion with the surrounding areas, which can lead to cracks in the mold. For this reason, other techniques for cooling the mold so that the mold release agent can adhere have been desired.

The present disclosure has been made to solve the above-mentioned problems, and can be realized in the following forms.
According to one embodiment of the present disclosure, there is provided a release agent spraying device that sprays a release agent onto a mold. The release agent spraying device includes a release agent spraying section that sprays a release agent, a gas injection section that injects a gas, and a control section that controls the release agent spraying section and the gas injection section to perform a release agent attachment process, and the release agent attachment process includes a gas injection process and a release agent spraying process that is performed after the gas injection process. The gas injection process is a process in which the gas injection section injects a gas toward the mold, and the release agent spraying process is a process in which the release agent spraying section sprays the release agent toward the mold, and is performed when the temperature of the mold is lower than a certain temperature. The control section controls the gas injection section to perform the gas injection process so that the flow rate of the injected gas is increased as the difference between the temperature of the mold before the gas is injected and the certain temperature increases.

(1) According to one aspect of the present disclosure, there is provided a release agent spraying device that sprays a release agent onto a mold. This release agent spraying device includes a release agent spraying unit that sprays a release agent, a gas injection unit that injects a gas, and a control unit that controls the release agent spraying unit and the gas injection unit to perform a release agent adhesion process. The release agent adhesion process includes a gas injection process and a release agent spraying process that is performed after the gas injection process. The gas injection process is a process in which the gas injection unit injects a gas toward the mold. The release agent spraying process is a process in which the release agent spraying unit sprays the release agent toward the mold, and is performed when the temperature of the mold is lower than a certain temperature.
In this embodiment, the die is cooled by gas, so that only the surface of the die is cooled, and the thickness of the cooled part is thin, so that the difference in the amount of thermal expansion with the surrounding parts is small. Therefore, the die can be cooled so that the release agent can adhere while suppressing the occurrence of cracks in the die. In addition, the amount of the release agent to be sprayed can be reduced compared to the case where the die is cooled by the release agent.
(2) In the above-described form of the mold release agent spraying device, a temperature sensor may be provided for measuring a temperature of the mold, and the control unit may start the mold release agent deposition process in response to detecting that the temperature measured by the temperature sensor during the gas injection process is lower than the certain temperature.
With this configuration, the control unit can more reliably determine that the mold temperature has dropped to a certain temperature, compared to a case in which a temperature sensor is not provided.
(3) In the release agent spraying device of the above aspect, the control unit may execute the gas injection process by controlling the gas injection unit so that the flow rate of the injected gas is increased as the difference between the temperature of the mold before the gas is injected and the certain temperature increases.
The faster the flow rate of the injected gas, the lower the mold temperature can be, so with this embodiment, even if the mold temperature is high, the mold temperature can be lowered to a certain temperature.
(4) In the above-described release agent spraying device, the release agent spraying process may be started at the same time that the temperature of the mold is lowered to the certain temperature in the gas injection process.
In this manner, the release agent can be applied before the temperature of the mold rises again, so that a film of the release agent can be reliably formed on the mold.
(5) In the release agent spraying device of the above aspect, the gas injection section and the release agent spraying section may each inject the gas and spray the release agent through the same nozzle.
In this manner, the center line of the flow of the injected gas coincides with the center line of the flow of the sprayed release agent, so that the release agent can be accurately sprayed onto the die in accordance with the temperature of the die cooled by the injection of the gas.

This disclosure can be realized in various forms, for example, as a release agent spray system.

FIG. 2 is a diagram showing a schematic configuration of a release agent spraying device. 10 is a flowchart showing an example of a release agent application process. FIG. 13 is an explanatory diagram of a release agent attachment treatment in a comparative example. FIG. FIG. 13 is an explanatory diagram showing the temperature of a mold cooled by a gas injection process. 11 is a graph showing the relationship between the flow rate of gas injected from the gas injection part and the decrease in temperature of the mold.

A. First embodiment:
1 is a diagram showing a schematic configuration of a release agent spraying device in one embodiment of the present disclosure. The release agent spraying device 100 is a device that sprays a release agent onto a surface (hereinafter simply referred to as "surface") 201 that defines a cavity, which is a molding part of a mold 200. The release agent spraying device 100 includes a gas injection unit 10, a release agent spraying unit 20, a control unit 30, and a temperature sensor 40.

The gas ejection unit 10 ejects gas. The gas ejection unit 10 ejects gas contained in the tank 11 through the nozzle 110. The gas is, for example, air.

The release agent spraying unit 20 sprays the release agent. The release agent spraying unit 20 sprays the release agent stored in the release agent tank 21 through a nozzle 110. In this embodiment, the gas injection unit 10 and the release agent spraying unit 20 each inject gas and spray the release agent through the same nozzle 110. The release agent is composed of an aggregate that forms a protective film on the surface of the mold and a liquid carrier that disperses the aggregate. The aggregate is, for example, silicon oil. The liquid carrier is, for example, water.

The control unit 30 controls the gas injection by the gas injection unit 10 and the spraying of the release agent by the release agent spray unit 20 to perform the release agent attachment process. In this embodiment, the control unit 30 is composed of a microcomputer composed of a central processing unit (CPU), RAM, and ROM, and realizes the functions of the gas injection unit 10 and the release agent spray unit 20 by the microcomputer executing a program installed in advance. However, some or all of the functions of these units may be realized by a hardware circuit. In this embodiment, the control unit 30 controls the injection of gas by the gas injection unit 10 and the spraying of the release agent by the release agent spray unit 20 according to the temperature measured by the temperature sensor 40. When the temperature of the mold 200 is higher than a predetermined threshold temperature, the control unit 30 does not allow the release agent spray unit 20 to spray the release agent toward the mold 200.

The temperature sensor 40 is a sensor that measures the temperature of the mold 200 without contact. The temperature of the mold 200 refers to the surface temperature of the face 201.

Figure 2 is a flow chart showing an example of a release agent deposition process. The release agent deposition process is a process in which a release agent is deposited on a surface 201 by a release agent spray device 100.

In step S100, a gas injection process is performed. In step S100, the gas injection unit 10 injects gas onto the surface 201 of the mold 200. More specifically, before the release agent is sprayed from the release agent spray unit 20, the control unit 30 causes the gas injection unit 10 to inject gas toward the mold 200 until the temperature of the mold 200 drops to a certain temperature. This process is also called a "gas injection process". In this embodiment, the gas injection unit 10 moves the nozzle 110 by a robot to inject gas onto the surface 201. In this embodiment, the control unit 30 detects whether the temperature of the mold 200 has dropped to a predetermined threshold temperature using the temperature measured by the temperature sensor 40. The threshold temperature is a temperature at which the occurrence of the Leidenfrost phenomenon is suppressed and the release agent sprayed onto the surface 201 can form a coating on the surface 201, and can be determined in advance by experiment. In this embodiment, the control unit 30 controls the gas injection unit 10 to stop injecting gas into the mold 200 as soon as the temperature of the mold 200 drops to the threshold temperature, and proceeds to the process of step S110. "As soon as the temperature of the mold 200 drops to the threshold temperature" refers to within one second, for example.

In step S110, the release agent spraying process is performed when the temperature of the mold 200 is lower than a certain temperature. That is, step S110 is not performed when the temperature of the mold 200 is higher than a certain temperature. In step S110, the release agent spraying unit 20 sprays the release agent onto the surface 201 of the mold 200 whose temperature has dropped below a certain temperature. More specifically, when the temperature of the mold 200 has dropped to a threshold temperature, the control unit 30 causes the release agent spraying unit 20 to spray the release agent toward the mold 200. This process is also referred to as the "release agent spraying process." In this embodiment, the release agent spraying unit 20 moves the nozzle 110 by a robot to spray the release agent onto the surface 201.

3 is an explanatory diagram of the release agent attachment process in the comparative example, and FIG. 4 is an explanatory diagram of the gas injection process in this embodiment. FIG. 3 shows a case where the temperature of the mold 200 is lowered to a threshold temperature by spraying the release agent. As shown in FIG. 3, when the mold 200 is cooled by a liquid release agent, the surface layer A1 within the range from the surface of the mold 200 to the thickness t1 is rapidly cooled and the temperature is lowered. As shown in FIG. 4, when the mold 200 is cooled by gas, the temperature of the surface portion A2 within the range from the surface of the mold 200 to the thickness t2 is lowered. The thickness t2 of the surface portion A2 is thinner than the thickness t1 of the surface portion A1. Therefore, the thermal expansion difference between the mold 200 in this embodiment and the surrounding parts is smaller than that in the comparative example. Therefore, it is possible to suppress the mold 200 from cracking due to the temperature difference.

According to the release agent spraying device 100 of this embodiment described above, the die 200 is cooled by gas, so that the surface portion A2 within the range of thickness t2 from the surface of the die 200 is cooled. Since thickness t2 is sufficiently thin, the difference in the amount of thermal expansion with the surrounding parts is small. Therefore, the die 200 can be cooled so that the release agent can adhere while suppressing the occurrence of cracks in the die 200. In addition, the amount of release agent sprayed can be reduced compared to when the die 200 is cooled by the release agent.

The release agent spraying device 100 is also equipped with a temperature sensor 40. In response to detecting that the temperature of the mold 200 is lower than a certain temperature during the gas injection process of step S100 (see FIG. 2), the control unit 30 can start the release agent spraying process of step S110. Therefore, the control unit 30 can more reliably spray the release agent onto the mold 200 when the temperature of the mold 200 has dropped to the threshold temperature, compared to, for example, a case in which the release agent spraying device 100 does not have a temperature sensor 40 and sprays the release agent after injecting gas for a predetermined time.

The control unit 30 also controls the release agent spray unit 20 to spray the release agent onto the mold 200 as soon as the temperature of the mold 200 drops to the threshold temperature. This allows the release agent to be applied before the temperature of the mold 200 rises again, ensuring that a coating of the release agent is formed on the mold 200.

The gas injection section 10 and the release agent spray section 20 each inject gas and spray the release agent through the same nozzle 110. Because the center line of the injected gas flow and the center line of the sprayed release agent flow coincide with each other, the release agent can be accurately sprayed onto the mold 200 in accordance with the temperature of the mold 200 cooled by the gas injection. In addition, the release agent spraying device 100 does not need to have a different nozzle for each material to be discharged. This makes it possible to prevent the release agent spraying device 100 from becoming large.

B. Second embodiment:
The release agent spraying device 100 in the second embodiment is different from the release agent spraying device 100 in the first embodiment in that the control unit 30 controls the gas injection unit 10 so as to increase the flow rate of the injected gas as the difference between the temperature of the mold 200 before the gas is injected and the threshold temperature increases. The other configurations are the same as those of the first embodiment.

Figure 5 is an explanatory diagram showing the temperature of the mold 200 cooled by the gas injection process. The upper part of Figure 5 is a plan view showing the surface 201 as viewed from the nozzle 110. The lower part of Figure 5 is a graph showing the temperature at each position separated in the left and right directions from the center P0 of the surface 201. The horizontal axis shows the distance of each position to the right of the center P0 as 0, and the distance of each position to the left of the center P0 as a negative value. When gas is ejected toward the center P0, the gas stagnates at the center P0, so that the temperatures at positions P1 and P2, which are position P1 shifted by a distance x from the center P0, are the lowest, as shown in Figure 5.

Figure 6 is a graph showing the relationship between the flow velocity of the gas injected by the gas injection section 10 and the decrease in temperature of the mold 200. Figure 6 shows the temperature at position P1 in Figure 5. Graph Gr1 shows the case where the flow velocity of the gas injected by the gas injection section 10 is 50 m/s, graph Gr2 shows the case where the flow velocity of the gas injected by the gas injection section 10 is 100 m/s, and graph Gr3 shows the case where the flow velocity of the gas injected by the gas injection section 10 is 200 m/s. As shown in Figure 6, the faster the flow velocity of the gas injected by the gas injection section 10 is, the lower the temperature of the mold 200 can be.

In this embodiment, the control unit 30 controls the gas injection unit 10 to increase the flow rate of the injected gas as the difference between the temperature of the mold 200 before the gas is injected and the threshold temperature increases. The faster the flow rate of the injected gas, the lower the temperature of the mold 200 can be. Therefore, even if the temperature of the mold 200 is high, the temperature of the mold 200 can be reduced to the threshold temperature.

C. Other embodiments:
(C1) In the above-described embodiment, the release agent spraying device 100 has only one nozzle 110, and the gas injection unit 10 and the release agent spraying unit 20 each inject the gas and spray the release agent through the same nozzle 110. Instead of this, the release agent spraying device 100 may have a plurality of nozzles 110. Furthermore, the release agent spraying device 100 may have a different nozzle for each material to be discharged. The gas injection unit 10 and the release agent spraying unit 20 each inject the gas and spray the release agent through a different corresponding nozzle.

(C2) In the above-described embodiment, the release agent spraying device 100 is equipped with a temperature sensor 40. However, the present invention is not limited to this, and the release agent spraying device 100 does not have to be equipped with a temperature sensor 40. In this case, the control unit 30 controls the gas ejection unit 10 to eject gas for a time period that is determined in advance experimentally or empirically.

(C3) In the above-described embodiment, the release agent spraying unit 20 uses a water-soluble release agent in which the liquid carrier that disperses the aggregate is water. However, the release agent spraying unit 20 may use an oil-based release agent in which the carrier is oil. The boiling point of an oil-based release agent is higher than that of a water-soluble release agent. For example, it is 220 degrees. Therefore, the threshold temperature when an oil-based release agent is used is set higher than the threshold temperature when a water-soluble release agent is used.

(C4) In the above-described embodiment, the control unit 30 controls the release agent spraying unit 20 to spray the release agent onto the mold 200 at the same time that the temperature of the mold 200 drops to the threshold temperature. However, the control unit 30 may also control the release agent spraying unit 20 to spray the release agent onto the mold 200 after a predetermined time has elapsed since the temperature of the mold 200 drops below the threshold temperature.

The present disclosure is not limited to the above-described embodiments, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in each form described in the Summary of the Invention column can be replaced or combined as appropriate to solve the above-described problems or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate.

10...gas injection section, 11...tank, 20...release agent spray section, 21...release agent tank, 30...control section, 40...temperature sensor, 100...release agent spray device, 110...nozzle, 200...mold, 201...surface, A1...surface layer, A2...surface section

Claims (5)

A release agent spraying device for spraying a release agent onto a mold,
A release agent spraying unit that sprays a release agent;
A gas ejection unit that ejects gas;
a control unit that controls the release agent spray unit and the gas injection unit to perform a release agent adhesion process,
the release agent attachment process includes a gas injection process and a release agent spray process carried out after the gas injection process,
the gas injection process is a process in which the gas injection unit injects gas toward the mold,
the release agent spraying process is a process in which the release agent spraying unit sprays the release agent toward the mold, and is executed when the temperature of the mold is lower than a certain temperature ;
the control unit controls the gas injection unit to perform the gas injection process so as to increase the flow rate of the gas to be injected as the difference between the temperature of the mold before the gas is injected and the certain temperature increases . 2. The release agent spraying device according to claim 1,
A temperature sensor is provided to measure the temperature of the mold,
The control unit starts the release agent attachment process in response to detecting that the temperature measured by the temperature sensor in the gas injection process is lower than the certain temperature. The release agent spraying device according to claim 1 or 2 ,
The control unit starts the release agent spraying process at the same time that the temperature of the mold is lowered to the certain temperature in the gas injection process. The release agent spraying device according to any one of claims 1 to 3 ,
the gas injection section and the release agent spray section inject the gas and spray the release agent through the same nozzle, respectively. A method for spraying a release agent onto a mold, comprising the steps of:
a gas injection step of injecting a gas toward the mold before spraying the release agent onto the mold;
a release agent spraying step of spraying the release agent toward the mold when the temperature of the mold is lower than a certain temperature after the gas injection step ,
the flow rate of the gas to be injected is increased as the difference between the temperature of the mold before the gas is injected and the certain temperature increases .

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