JP5099469B2 - Rubber mold manufacturing method and rubber molding method using the rubber mold - Google Patents

Description

  The present invention relates to a method for manufacturing a rubber mold and a rubber molding method using the rubber mold, and in particular, a method for manufacturing a rubber mold based on a novel concept focusing on a casting temperature when manufacturing a rubber mold. And a rubber molding method using the rubber molding die.

  Conventionally, a rubber mold is used to apply a molding pressure generated on the basis of the thermal expansion of the rubber mold at the molding temperature of the molding (for example, FRP (fiber reinforced plastic) molding) to the molding. A rubber molding method in which a molded product is molded is known (for example, Patent Document 1 and Patent Document 2). This rubber molding method is generally said to be suitable for molding a molding having a relatively complicated surface shape, particularly a molding using a prepreg. However, the rubber molding method disclosed in Patent Document 1 cannot be used for molding a molded product having a closed space because the core is taken out from the molded product after molding the molding.

In such a conventional rubber molding method, a rubber molding die is placed in a rigid outer mold (casing) with a gap, and molding occurs based on the thermal expansion of the rubber molding die in the rubber molding die cavity. While applying pressure to the molding object, the molding object is molded by heating. The pressure generated during heating in this rubber molding is controlled mainly by the gap between the casing and the rubber mold, but the initial dimensions and internal stress of the rubber mold are uncontrolled or unstable. There is a problem that the control amount differs for each mold or the molding pressure applied to the molding varies, and a molded article having a predetermined shape cannot be stably obtained. In particular, when the molding has a shape having a hollow closed space, there is a problem that the cross-sectional deformation of the molding becomes large.
Japanese Patent Laid-Open No. 3-272732 JP-A-4-294126

  Accordingly, an object of the present invention is to stably control a molding pressure applied from a rubber mold to a workpiece to a predetermined target pressure, and to mold a predetermined shape, particularly a shape having a closed space. An object of the present invention is to provide a rubber molding die manufacturing method and a rubber molding method using the rubber molding die that can stably mold even a product.

  In order to solve the above-mentioned problems, a rubber molding die manufacturing method according to the present invention is a rubber molding die capable of applying a molding pressure generated based on its own thermal expansion at a molding temperature of the molding to the molding. In casting, the casting temperature is set with a temperature difference obtained in advance by calculation with respect to the molding temperature of the molding object.

This method for producing a rubber mold comprises, in particular, a method characterized by casting the rubber mold at a temperature obtained by subtracting the temperature difference ΔT calculated by the following equation from the molding temperature of the molding. .
ΔT = (P / E + δ / L) / α
here,
P: Molding pressure of the molding E: Longitudinal elastic modulus of rubber δ: Gap between the cavity of the rubber molding die and the molding L: Thickness in the molding pressure loading direction of the rubber molding die α: Linear expansion coefficient of the rubber It is.

  In the method for manufacturing a rubber mold according to the present invention, the rubber mold may be composed of a split mold having at least an upper mold and a lower mold, for example. With the split mold, it is possible to easily form a cavity with a predetermined shape in the assembled split mold even when the surface shape of the molding is a complicated shape such as a curved surface. .

  The rubber mold is usually used by being installed in a rigid outer mold (sometimes called a casing). That is, with the outer mold made of a rigid body having a fixed shape as a reference, the rubber mold is thermally expanded at the time of molding toward the cavity side, and the molding pressure generated based on the thermal expansion is applied to the object to be molded. The molded product is molded.

  This rubber mold is used, for example, for molding FRP as a molding object. Among them, it is used for molding FRP having a relatively complicated surface shape.

  In addition, this rubber mold is particularly suitable for use in molding a molding having a closed space inside. That is, it is possible to stably apply a predetermined molding pressure generated based on the thermal expansion of the rubber mold from the outside without causing a harmful deformation of the cross-sectional shape of the molding while the closed space is formed inside. become.

  The material of the rubber mold is not particularly limited, but considering the relationship with the molding temperature, it has high heat resistance, high elasticity, and excellent releasability after molding of the molding. preferable. In particular, it is preferably made of silicone rubber, but in addition, fluorine-based rubber or the like can be applied.

  The rubber molding method according to the present invention comprises a method characterized by molding a molding using a rubber molding die manufactured by the method as described above.

  In this rubber molding method, the rubber mold is placed in the outer mold in contact with the inner surface of a rigid outer mold (sometimes referred to as a casing), and in the cavity of the rubber mold. It is preferable to mold the molding object. In particular, since the rubber mold has a gap (δ) between the cavity of the rubber mold and the object to be molded when ΔT is determined in advance, the surface on the side opposite to the cavity of the rubber mold is the inner surface of the outer mold. With this, it is not necessary to control the gap between them as in the conventional method, and the rubber mold only needs to be thermally expanded exclusively in the cavity direction.

  Also in this rubber molding method, FRP can be molded as a molding object. In particular, this rubber molding method is a suitable method for molding a molding including a reinforcing fiber prepreg. In addition, a molded article having a closed space inside can be stably molded into a target shape.

  According to the rubber molding die manufacturing method and the rubber molding method using the rubber molding die according to the present invention, the temperature at which the molding temperature of the rubber molding die is calculated in advance with respect to the molding temperature of the molding object. The temperature set with the difference, especially the molding temperature of the molding, the molding pressure of the molding, the elastic modulus of rubber, the gap between the rubber mold cavity and the molding, the molding of the rubber molding Conversely, by setting the temperature minus the temperature difference ΔT calculated using the thickness in the pressure load direction and the linear expansion coefficient of the rubber, the temperature difference between the casting temperature and the molding temperature (heating temperature) is managed. Thus, the molding pressure actually applied during molding can be stably managed at the target pressure. As a result of being stably controlled to a predetermined molding pressure as a target, even a molded product having a complicated shape, for example, a complicated shape having a closed space, can be stably molded.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a rubber molding die and a rubber molding method using the rubber molding die according to an embodiment of the present invention. In FIG. 1, an object 1 is composed of a combination of a pre-cured FRP or resin upper shell 2 and lower shell 3 so as to form a closed space 4. These reinforced fiber prepregs 5 are made of a single layer or multiple layers laminated and wound in a headband shape. In this embodiment, a cover film 6 (for example, a heat-shrinkable polypropylene film) for maintaining the shape, for fastening, or for forming the outermost layer is wound on the outer layer side of the reinforcing fiber prepreg 5.

  The molding 1 is placed in a cavity 9 formed by an upper rubber molding die 7 and a lower rubber molding die 8 made of a split die, with a gap between the inner surface of the cavity 9. The upper rubber molding die 7 and the lower rubber molding die 8 are placed in contact with the inner surfaces of the casings 10 and 11 in an upper casing 10 and a lower casing 11 as outer molds made of a rigid body. The upper rubber mold 7 and the lower rubber mold 8 are made of, for example, silicone rubber. In this state, it is heated to a temperature (molding temperature) necessary for molding the molding 1 and molding is performed.

  Since the upper rubber mold 7 and the lower rubber mold 8 are in contact with the upper casing 10 and the lower casing 11 made of rigid bodies, when heated to the molding temperature, the inner surfaces of the upper casing 10 and the lower casing 11 are used as a reference. As a surface, it thermally expands substantially only in the direction of the cavity 9. The molding pressure generated based on the thermal expansion is applied to the molding 1 from the time when the thermally expanded rubber molding dies 7 and 8 come into contact with the molding 1, and the molding 1 has a target shape. It is formed into a product.

This molding pressure is set and managed as follows. That is, first, when the rubber molds 7 and 8 themselves are manufactured by casting, the casting temperature is set with respect to the molding temperature of the molding 1 with a temperature difference obtained in advance by calculation. In particular, the rubber mold is cast at a temperature obtained by subtracting the temperature difference ΔT calculated by the following equation from the molding temperature of the article 1.
ΔT = (P / E + δ / L) / α
here,
P: Molding pressure of the molding E: Longitudinal elastic modulus of rubber δ: Gap between the cavity of the rubber molding die and the molding L: Thickness in the molding pressure loading direction of the rubber molding die α: Linear expansion coefficient of the rubber It is.

  The relationship according to the above equation is shown in FIG. That is, in the conventional rubber molding, the set temperature difference and the casting temperature as described above are not taken into consideration and managed, but in the present invention, the molding temperature (heating temperature) of the molding 1 is not controlled. Thus, the rubber molds 7 and 8 are manufactured at the casting temperature subtracted by ΔT, that is, at the casting temperature intentionally controlled as described above.

  In the rubber molds 7 and 8 manufactured in this way, the temperature difference between the casting temperature and the molding temperature (heating temperature) is intentionally managed by managing the casting temperature as described above. Thus, the generated pressure (that is, the molding pressure that is actually applied) calculated from the dimensions of the rubber mold and the linear expansion coefficient of the rubber can be set as the management value, as in the above formula. As a result, it becomes possible to stably apply a target predetermined molding pressure. Therefore, variations in the molded product are suppressed, and a molded product having a stable quality and shape can be obtained.

  In addition, the shape and structure of FRP molding itself shape | molded in the said embodiment are not specifically limited, The kind of the reinforced fiber and matrix resin is also not specifically limited.

  The method for producing a rubber mold and the rubber molding method using the rubber mold according to the present invention can be applied to all types of rubber molding, and are particularly suitable for rubber molding of FRP having a complicated shape having a closed space. .

It is a schematic sectional drawing which shows the rubber molding die which concerns on one embodiment of this invention, and the rubber molding method using the rubber molding die. It is a characteristic view which shows the concept of the temperature difference setting of the shaping | molding temperature and casting temperature in this invention.

Explanation of symbols

1 Molded object 2 Upper shell 3 Lower shell 4 Closed space 5 Uncured reinforcing fiber prepreg 6 Cover film 7 Upper rubber mold 8 Lower rubber mold 9 Cavity 10 Upper casing 11 Lower casing

Claims (12)

  When casting a rubber mold that can apply a molding pressure generated based on its own thermal expansion at the molding temperature of the molding to the molding, the casting temperature is set to the molding temperature of the molding. On the other hand, a method for manufacturing a rubber mold, wherein the temperature difference is set in advance by calculation. The method for producing a rubber mold according to claim 1, wherein the rubber mold is cast at a temperature obtained by subtracting a temperature difference ΔT calculated by the following formula from a molding temperature of the molding.
ΔT = (P / E + δ / L) / α
here,
P: Molding pressure of the molding E: Longitudinal elastic modulus of rubber δ: Gap between the cavity of the rubber molding die and the molding L: Thickness in the molding pressure loading direction of the rubber molding die α: Linear expansion coefficient of the rubber It is.   The method for producing a rubber molding die according to claim 1 or 2, wherein the rubber molding die comprises a split die having at least an upper die and a lower die.   The method for producing a rubber mold according to any one of claims 1 to 3, wherein the rubber mold is used by being installed in an outer mold made of a rigid body.   The method for producing a rubber molding die according to any one of claims 1 to 4, wherein the rubber molding die is used for molding an FRP as the molding object.   The method for producing a rubber molding die according to any one of claims 1 to 5, wherein the rubber molding die is used for molding a molding having a closed space inside.   The method for producing a rubber mold according to claim 1, wherein the rubber mold is made of silicone rubber.   A rubber molding method comprising molding a molding using the rubber molding die manufactured by the method according to claim 1.   The rubber molding method according to claim 8, wherein the rubber molding die is placed in contact with an inner surface of an outer mold made of a rigid body and is molded in the cavity of the rubber molding die. .   The rubber molding method according to claim 8 or 9, wherein FRP is molded as the molding object.   The rubber molding method according to claim 10, wherein a molding including a reinforcing fiber prepreg is molded.   The rubber molding method according to claim 8, wherein a molding having a closed space inside is molded.

Images