Patent Description:
The related art display is provided with cover glass for protecting the display. The cover glass should be highly light-transmissive and non-fragile. On the other hand, with development of display technologies, a curved display has begun to be developed, and accordingly, a demand for cover glass in a curved shape is increasing.

Various glass molding methods are utilized to produce curved cover glass. Since the dimension of the cover glass applied to the curved display must have an error range of several hundred micrometers, very high precision is needed for production. To this end, a press molding method having high molding precision may be utilized.

Meanwhile, attempts have been made to apply the curved display to the front and rear surfaces of a vehicle. Accordingly, the demand for large curved glasses is increasing. Even though using the press molding method with high precision, when processing large glass, it is difficult to mold the glass within an error range of several hundred micrometers. Therefore, a demand for a more precise glass molding method is increasing.

<CIT> discloses an apparatus for manufacturing 3D glass. <CIT> discloses a glass molding die for press-molding glass products.

One aspect of the present disclosure is to provide a manufacturing method of increasing precision for molding glass into a curved shape and simultaneously reducing a glass molding time.

Detailed aspects of the present disclosure are as follows.

First, the present disclosure is directed to preventing flat glass from being damaged due to the weight of an upper mold when performing a molding (or forming) process after primarily aligning a lower mold, the flat glass, and the upper mold.

Secondly, the present disclosure is directed to preventing reduction of molding precision, which is caused by a mold damaged due to repetitive use.

Third, the present disclosure is directed to minimizing a supply rate and a supply amount of nitrogen gas for preventing oxidization of a mold during a molding process.

The invention defined in the appended independent claim achieves these advantages identified above. In the following description, there is provided a method for manufacturing curved glass, the method including, a first step of sequentially stacking a lower mold, flat glass, and an upper mold to form a mold assembly, a second step of moving the mold assembly to a first chamber and heating the mold assembly, a third step of moving the mold assembly from the first chamber to a second chamber and pressurizing the upper mold downward to mold the flat glass into a curved shape, a fourth step of moving the mold assembly from the second chamber to a third chamber and then slowly cooling the molded glass, and a fifth step of moving the mold assembly from the third chamber to a fourth chamber and then cooling the molded glass. An elastic member may be disposed between the lower mold and the upper mold so that the upper mold is spaced apart from the flat glass, and may be compressed when the upper mold is pressurized.

The first chamber may have an internal temperature in a range of room temperature to <NUM>, the second chamber may have an internal temperature in a range of <NUM> to <NUM>, the third chamber may have an internal temperature in a range of <NUM> to <NUM>, and the fourth chamber may have an internal temperature in a range of room temperature to <NUM>.

The elastic member may not reach a plastic limit at a temperature of <NUM> or lower, even if compressed by the upper mold.

The elastic member may be made of Ni, Cr, Ti and Al alloy.

In the third step, the upper mold may be pressurized to be fixed to the lower mold, and the fourth and fifth steps may be performed in a state where the upper mold is fixed to the lower mold.

An inside of each of the first to third chambers may be formed in a nitrogen atmosphere.

The second step may include moving the mold assembly to a first sub chamber and then forming an inside of the first sub chamber in a nitrogen atmosphere, moving the mold assembly from the first sub chamber to a second sub chamber in a nitrogen atmosphere, and moving the mold assembly to the first chamber. The first sub chamber may have a volume smaller than a volume of the second sub chamber.

In the moving of the mold assembly to the first sub chamber and then forming of the inside of the first sub chamber in the nitrogen atmosphere, nitrogen pressure inside the first sub chamber may be greater than nitrogen pressure in the second sub chamber.

The fifth step may include moving the mold assembly from the third chamber to a third sub chamber in a nitrogen atmosphere, moving the mold assembly from the third sub chamber to a fourth sub chamber in a nitrogen atmosphere, and moving the mold assembly from the fourth sub chamber to the fourth chamber in an air atmosphere. The fourth sub chamber may have a volume smaller than a volume of the third sub chamber.

The moving of the mold assembly from one of the first to fourth chambers to another chamber may include moving a transferring bar disposed below the one chamber into the one chamber to lift the mold assembly from below the mold assembly, horizontally moving the mold assembly to the another chamber while the transferring bar is lifting the mold assembly, and putting the mold assembly down on a bottom surface of the another chamber while the transferring bar is moved to a lower side of the another chamber.

Each of the first to fourth chambers may have a hole formed through a bottom surface thereof to allow movement of the transferring bar, and the transferring bar may be horizontally moved along the hole.

A partition wall may be disposed between the one chamber and the another chamber to be opened and closed, and may be opened when the transferring bar is horizontally moved.

The partition wall may be provided with a hole formed therethrough to allow the transferring bar to be horizontally moved between the one chamber and the another chamber.

A first hot plate is brought into contact with an upper side of the upper mold and a lower side of the lower mold when the mold assembly is located in the first to third chambers, and the first hot plate includes a heating portion in which temperature increases as a current flows, and a heat transfer layer covering the heating portion.

A thickness of the heat transfer layer relative to a width of the first hot plate may be in a range of <NUM> to <NUM>.

The heat transfer layer may be made of one of graphite, anti-oxidation coated graphite, and a ceramic material.

A second hot plate may be disposed on a side surface of each of the first to third chambers, and the second hot plate disposed in any one of the first to third chambers may have a temperature higher than a temperature of the first hot plate disposed in the one chamber.

According to the present disclosure, when a lower mold, flat glass, and an upper mold are sequentially aligned, the flat glass can be prevented from being damaged due to a weight of the upper mold. Accordingly, the molds and the glass can primarily be aligned before a glass molding process, thereby improving molding precision.

According to the present disclosure, since an impact applied to a mold during a molding process can be minimized, the mold can be prevented from being damaged during the molding process.

According to the present disclosure, a supply time and a supply amount of nitrogen gas for preventing oxidization of a mold during a molding process can be reduced, thereby shortening a glass molding time and reducing a molding cost.

Description will now be given in detail according to exemplary embodiments disclosed herein, with reference to the accompanying drawings. For the sake of brief description with reference to the drawings, the same or equivalent components may be provided with the same or similar reference numbers, and description thereof will not be repeated. In describing the present disclosure, if a detailed explanation for a related known function or construction is considered to unnecessarily divert the gist of the present disclosure, such explanation has been omitted but would be understood by those skilled in the art. The accompanying drawings are used to help easily understand the technical idea of the present disclosure and it should be understood that the idea of the present disclosure is not limited by the accompanying drawings. The idea of the present disclosure should be construed to extend to any alterations, equivalents and substitutes besides the accompanying drawings.

Prior to describing a method for producing curved glass according to the present disclosure, press molding according to the related art will be described.

In the related art press molding method, flat glass is placed on a lower mold and then heated. Thereafter, the flat glass is pressurized by a heated upper mold.

In the case of molding the glass by the method, it is difficult to process the glass within an error range of several hundred micrometers when an area of the glass to be formed is increased.

Molding precision may be improved by utilizing a scheme of pressurizing an upper mold after primarily aligning the lower mold, the flat glass, and the upper mold. However, when this method is applied to form large glass, there is a problem that the glass is likely to be broken due to the weight of the upper mold. Specifically, when the area of the glass to be processed is increased, the size of the molds is necessarily increased. This causes the increase in weight of the glass. Glass utilized for cover glass has a thickness of about <NUM> to <NUM>, and the glass with this thickness may be broken without bearing the increased weight of the upper mold. The present disclosure provides a manufacturing method capable of preventing glass from being broken when primarily aligning a lower mold, a flat glass and an upper mold.

On the other hand, when a large impact is applied to a mold during the press molding, the mold may be damaged. Accordingly, when the mold is reused, molding precision may be lowered. In addition, an impact applied to a mold during a molding process may be delivered even to glass and the glass may be broken. The present disclosure provides a manufacturing method capable of minimizing an impact applied to a mold during a molding process.

On the other hand, the press molding method is carried out at a high temperature of several hundred degrees (°C), and the mold may be oxidized at this temperature. If the mold is oxidized, a surface and the like may be damaged and precision of glass processing may be degraded. To prevent this, a space in which the molding process takes place is filled with nitrogen gas. External air may be introduced into the space when supplying new glass or whenever processed glass is discharged. Therefore, the nitrogen gas should be periodically supplied into the space. This causes a problem that a processing time and a process cost increase. The present disclosure minimizes a nitrogen supply time and minimizes an amount of nitrogen used by way of minimizing the size of the space filled with the nitrogen.

Hereinafter, the manufacturing method for achieving the above-mentioned aspects will be described.

<FIG> is a conceptual view illustrating a glass manufacturing method in accordance with the present disclosure, <FIG> is a perspective view of a mold in accordance with the present disclosure, and <FIG> is a cross-sectional view of a mold in accordance with the present disclosure.

First, in the present disclosure, a first step of forming a mold assembly by sequentially stacking a lower mold, a flat glass, and an upper mold is performed.

As illustrated in <FIG>, a mold may include an upper mold <NUM> and a lower mold <NUM>. The lower mold <NUM>, the flat glass and the upper mold <NUM> are primarily assembled together.

As described above, the movement of the molds in the primarily assembled mold assembly <NUM> is limited in a predetermined direction. For example, in the mold assembly, the upper mold <NUM> may only move up and down with respect to the lower mold <NUM>.

To this end, each of the lower and upper molds may be provided with a guide for guiding the movement of the upper mold when the upper mold is aligned with the lower mold. For example, referring to <FIG>, a plurality of holes <NUM> may be formed in an edge of the lower mold, and a plurality of concave-convex structures <NUM> may be formed on an edge of the upper mold. When the concave-convex structures are inserted into the holes, the upper mold can only move up and down with respect to the lower mold. However, the present disclosure is not limited thereto. Alternatively, the lower mold may include the concave-convex structures and the upper mold may include the holes. Also, such element for guiding the movement of the upper mold is not limited to the holes and the concave-convex structures.

As described above, when glass molding is performed after the lower mold and the upper mold are primarily aligned with each other, the molds can move only in a specific direction, which may result in improving molding precision.

On the other hand, when the lower and upper molds are aligned with each other, a flat glass is disposed between the lower and upper molds. At this time, the load (or weight) of the upper mold may be delivered to the glass. In this case, the glass may be likely to be broken. To prevent this, an elastic member may be interposed between the lower and upper molds.

The elastic member may be disposed on the edge of the lower mold. For example, when the holes are provided in the edge of the lower mold, the elastic member may be disposed inside the holes. When the upper mold is aligned with the lower mold, the elastic member pushes up the upper mold, thereby preventing the load of the upper mold from being transferred to the flat glass.

For example, referring to <FIG>, an elastic member <NUM> may be disposed in the holes formed in the lower mold. The elastic member <NUM> may push up the concave-convex structures <NUM> formed on the upper mold <NUM> to prevent the upper mold <NUM> from being brought into contact with the flat glass.

On the other hand, although not shown, the elastic member <NUM> may be disposed on an intermediate mold interposed between the lower mold and the upper mold. Specifically, the intermediate mold may be disposed between the lower mold and the upper mold. The intermediate mold may be provided with a structure for guiding the movement of the lower mold and the upper mold, and the elastic member disposed on the intermediate mold may push up the upper mold.

The elastic member should be formed of a material which does not reach a yield point even if it is compressed by the upper mold at a temperature of <NUM> or lower. In detail, the lower mold, the flat glass, and the upper mold are heated up to a temperature of <NUM> at a second step to be explained later, and then formed. Accordingly, the elastic member should be able to prevent the load of the upper mold from being transferred to the flat glass by pushing up the upper mold even at the temperature of <NUM>. That is, the elastic member should not lose an elastic force even at the temperature of <NUM>. To this end, the elastic member may be an alloy consisting of Ni, Cr, Ti and Al alloy. For example, the elastic member may be mnemonic <NUM>.

The elastic member has an elastic force which is strong enough to push the upper mold upward, but is compressed when pressure is applied to the upper mold in a third step to be described later. Accordingly, the upper mold is brought into contact with the flat glass.

As the mold assembly passes through four different chambers, the flat glass is formed into a curved surface. Hereinafter, steps performed in each of the four chambers will be described.

In the present disclosure, a second step (S110) of heating the mold assembly after moving the mold assembly to a first chamber is performed.

In the first chamber <NUM>, the flat glass <NUM> is heated up to a temperature of enabling glass molding. Here, the temperature of enabling the glass molding is in the range of <NUM> to <NUM>. The temperature of enabling the glass molding may differ depending on a type of glass.

In the second step, each of the lower and upper molds may be heated by different hot plates. Specifically, a hot plate (hereinafter, referred to as a lower hot plate) may be fixed to a bottom surface of the first chamber, and a hot plate (hereinafter, referred to as an upper hot plate) that is disposed to be movable up and down may be disposed above the first chamber. The lower mold <NUM> is heated by the lower hot plate as the mold assembly <NUM> is seated on the bottom surface of the first chamber.

Meanwhile, the upper hot plate comes into contact with the upper mold <NUM> by way of the up-and-down movement after the mold assembly is moved to the first chamber. As a result, the upper mold <NUM> is heated. In this case, the load of the upper hot plate may be prevented from being transferred to the upper mold <NUM>.

On the other hand, a hot plate (hereinafter, a side hot plate) different from the upper and lower hot plates may be disposed on a side surface of the first chamber <NUM>. The side hot plate may be disposed in the first to third chambers. This will be described later.

When the flat glass is heated to a predetermined temperature, a third step (S120) of molding the flat glass after moving the mold assembly to the second chamber <NUM> is carried out.

Specifically, a step of molding the flat glass into a curved shape is performed in the second chamber. When the mold assembly heated to a predetermined temperature is moved to the second chamber, the upper hot plate disposed above the mold assembly <NUM> is placed on the upper mold <NUM> to pressurize the upper mold <NUM>. That is, the upper hot plate disposed in the second chamber is used not only as an element for heating the upper mold <NUM> but also as an element for pressurizing the upper mold <NUM>. However, the present disclosure is not limited thereto, and the upper hot plate may alternatively be pressurized by a separate pressurizing element so as to pressurize the upper mold <NUM> in the second chamber <NUM>.

As the upper mold <NUM> is pressurized, a distance between the upper and lower molds <NUM> and <NUM> is narrowed, and accordingly the flat glass disposed between the upper and lower molds <NUM> and <NUM> is processed (machined).

While the glass is being molded, an internal temperature of the second chamber is maintained at a temperature in the range of <NUM> to <NUM>. To this end, the upper mold <NUM> is heated by the upper hot plate and the lower mold <NUM> is continuously heated by the lower hot plate disposed on the bottom surface of the second chamber.

On the other hand, as the upper mold <NUM> is pressurized, the elastic member <NUM> disposed between the upper and lower molds <NUM> and <NUM> is compressed. The elastic member <NUM> is kept compressed while the glass is molded, and does not reach a plastic limit.

When the third step is completed, the upper hot plate disposed inside the second chamber <NUM> is moved to an upper side of the second chamber <NUM>. Accordingly, since pressure applied to the upper mold <NUM> disappears, the upper mold <NUM> is pushed upward by the elastic member <NUM>. Accordingly, the molded glass and the upper mold <NUM> may be spaced apart from each other. The mold assembly <NUM> may be moved to the third chamber while the molded glass and the upper mold are spaced apart from each other.

Thereafter, when the mold assembly <NUM> is moved from the third chamber <NUM> to the fourth chamber <NUM>, the upper mold <NUM> may be spaced apart from the glass whenever it is discharged from the fourth chamber <NUM>. However, when the glass is completely molded, the upper mold <NUM> does not need to be spaced apart from the glass anymore. To prevent an impact from being applied to the glass due to the upper mold <NUM> being repeatedly brought into contact with and spaced apart from the glass, the upper mold <NUM> may be fixed to the lower mold <NUM> after the third step.

To this end, the lower mold <NUM> may be provided with a fixing element for fixing the upper mold <NUM>, and the upper mold <NUM> may be fixed to the lower mold <NUM> after being pressurized in the third step. Accordingly, in fourth and fifth steps to be described later, the upper mold <NUM> may not be spaced apart from the glass.

When the glass molding is completed, a fourth step (S130) of moving the mold assembly to the third chamber to slowly cool the mold assembly is carried out.

When the glass heated up to <NUM> to <NUM> is directly exposed to room temperature, cracking may occur. Thus, the step of slowing cooling the glass is performed. The mold assembly <NUM> is cooled down to a temperature of <NUM> or lower in the third chamber <NUM>, and then moved to the fourth chamber <NUM>. Accordingly, an internal temperature of the third chamber <NUM> may be in the range of <NUM> to <NUM>.

After the mold assembly <NUM> is completely moved to the third chamber <NUM> from the second chamber <NUM>, the upper plate disposed in the third chamber <NUM> is brought into contact with the upper mode so as to slowly lower the temperature of the upper mold and the lower hot plate disposed in the third chamber slowly lowers the temperature of the lower mold.

When the fixing element for fixing the upper mold <NUM> to the lower mold <NUM> is not provided, the upper mold <NUM> is moved from the second chamber <NUM> to the third chamber <NUM> in a state of being spaced apart from the molded glass. When the upper plate disposed in the third chamber <NUM> is placed on the upper mold <NUM>, the upper mold <NUM> is brought into contact with the glass due to the load of the upper hot plate. The molded glass is slowly cooled in contact with the upper and lower molds <NUM> and <NUM>.

Finally, a fifth step (S140) of cooling the molded glass after the mold assembly <NUM> is moved from the third chamber <NUM> to the fourth chamber <NUM> is performed.

The molded glass is cooled down to room temperature in the fourth chamber <NUM>. When the glass is cooled down to the room temperature, the mold assembly <NUM> may be discharged to the outside, and the upper and lower molds <NUM> and <NUM> and the elastic member <NUM> may be recovered and reused.

Meanwhile, the upper and lower molds <NUM> and <NUM> may be oxidized by oxygen in the air at a temperature of <NUM> or higher. When the mold is oxidized, changes may occur, for example, the surface of the mold becomes rough, and the like, and thereby molding precision may be lowered. In order to prevent the mold from being oxidized during glass molding, the first to third chambers may be created in a nitrogen atmosphere.

On the other hand, since the internal temperature of the fourth chamber <NUM> is <NUM> or lower, the inside of the fourth chamber <NUM> does not need to be formed in the nitrogen atmosphere. By not filling the inside of the fourth chamber <NUM> with nitrogen, a nitrogen supply cost can be reduced.

Meanwhile, in order to prevent oxygen from flowing into the first to third chambers, the first to third chambers should be hermetically sealed. When the mold assembly <NUM> is moved from the outside to the first chamber <NUM>, it is difficult to maintain a sealed state when the mold assembly <NUM> is moved from the third chamber <NUM> to the fourth chamber <NUM>. The present disclosure provides a manufacturing method for minimizing a nitrogen loss that occurs when moving the mold assembly.

Hereinafter, a manufacturing method for minimizing a nitrogen loss will be described.

In order to minimize an amount of nitrogen lost when moving the mold assembly <NUM> from the outside to the first chamber <NUM>, the present disclosure can move the mold assembly <NUM> from the outside to the first chamber <NUM> through a loading part. Meanwhile, in order to minimize an amount of nitrogen lost when the mold assembly <NUM> is moved from the third chamber <NUM> to the fourth chamber <NUM>, the present disclosure can move the mold assembly <NUM> from the third chamber <NUM> to the fourth chamber <NUM> through an unloading part.

Hereinafter, the loading part and the unloading part will be described in detail.

<FIG> is a conceptual view illustrating a cross-section of a loading part, and <FIG> is a conceptual view illustrating a cross-section of an unloading part.

Referring to <FIG>, the loading part includes a first sub chamber <NUM> and a second sub chamber <NUM>. The mold assembly <NUM> is moved from outside to the first sub chamber <NUM>, and then moved from the first sub chamber <NUM> to the second sub chamber <NUM>. Thereafter, the mold assembly <NUM> is moved from the second sub chamber <NUM> to the first chamber <NUM>.

Whenever the mold assembly <NUM> is moved to each chamber, a gate located between the chambers is opened. At this time, gases in the two chambers are mixed with each other. When the mold assembly <NUM> is moved directly from the outside to the first chamber <NUM>, a sealed state of the first to third chambers which are sealed together may be broken. Accordingly, oxygen may be introduced into each of the first to third chambers.

To prevent this, after moving the mold assembly <NUM> to the sub chamber, the sub chamber is formed in a nitrogen atmosphere and then the mold assembly <NUM> is moved to the first chamber <NUM>. That is, the sub chamber should be formed in the nitrogen atmosphere every time when the mold assembly <NUM> is moved to the first chamber <NUM>.

When the volume of the sub chamber is reduced, a time for which the sub chamber is formed in the nitrogen atmosphere and an amount of nitrogen to be used may be reduced. However, it is difficult to reduce the volume of the sub chamber itself due to the volume of a transferring element for transferring (conveying, moving) the mold assembly <NUM>. Specifically, a nitrogen atmosphere should also be formed in a position where the transferring element for moving the mold assembly <NUM> is arranged. Thus, the transferring element must be arranged inside the sub chamber. Since the volume of the sub chamber has no option but to be increased because the transferring element has to be employed.

The present disclosure uses two sub chambers, in order to shorten a time for which sub chambers are formed in a nitrogen atmosphere and to minimize an amount of nitrogen to be used at this time. Specifically, the first sub chamber <NUM> has a volume similar to that of the mold assembly <NUM>. The first sub chamber <NUM> is provided with the least number of transferring elements to minimize the volume. For example, the first sub chamber <NUM> may include only a vertical (or perpendicular) transferring element.

As the mold assembly is moved into the first sub chamber <NUM>, the inside of the first sub chamber <NUM> is filled with air. Afterwards, the mold assembly <NUM> is moved to the second sub chamber <NUM> formed in the nitrogen atmosphere. Thus, before the movement, a step of forming the first sub chamber <NUM> in the nitrogen atmosphere is performed. Since the first sub chamber <NUM> has a very small volume, the nitrogen atmosphere can be quickly formed and a very small amount of nitrogen is used.

Thereafter, the mold assembly is moved from the first sub chamber <NUM> to the second sub chamber <NUM>. The second sub chamber <NUM> has a larger volume than the first sub chamber <NUM> because the second sub chamber <NUM> has horizontal and vertical transferring elements for transferring the mold assembly <NUM> to the first chamber <NUM>. The inside of the second sub chamber <NUM> should always be in the nitrogen atmosphere. Since the mold assembly <NUM> is moved after the first sub chamber <NUM> is formed in the nitrogen atmosphere, even if the mold assembly <NUM> is moved to the second sub chamber <NUM>, the nitrogen gas inside the second sub chamber <NUM> is not lost. Thereafter, the mold assembly <NUM> is moved from the second sub chamber <NUM> in the nitrogen atmosphere to the first chamber <NUM> in the nitrogen atmosphere.

Meanwhile, internal pressure of the first sub chamber <NUM> may be formed to be higher than atmospheric pressure by <NUM> to <NUM> Pa, and internal pressure of the second sub chamber <NUM> may be formed to be higher than the atmospheric pressure by <NUM> to <NUM> Pa. That is, the internal pressure pf the first sub chamber <NUM> may be higher than the internal pressure of the second sub chamber <NUM>. This is to replenish nitrogen lost in the second sub chamber <NUM> whenever the mold assembly is moved from the first sub chamber <NUM> to the second sub chamber <NUM>.

On the other hand, referring to <FIG>, the unloading part is formed symmetrically with the loading part. The unloading part includes a third sub chamber <NUM> and a fourth sub chamber <NUM>. Here, description of the third sub chamber <NUM> is replaced with the description of the second sub chamber <NUM>, and description of the fourth sub chamber <NUM> is replaced with the description of the first sub chamber <NUM>.

The mold assembly <NUM> is moved from the third chamber <NUM> to the third sub chamber <NUM> in a nitrogen atmosphere. Thereafter, the mold assembly <NUM> is moved from the third sub chamber <NUM> to the fourth sub chamber <NUM> and then moved to the fourth chamber <NUM> in an air atmosphere.

Before moving the mold assembly <NUM> from the third sub chamber <NUM> to the fourth sub chamber <NUM>, a step of forming the fourth sub chamber <NUM> in a nitrogen atmosphere is performed. This is to prevent oxygen, which has been introduced when moving the mold assembly <NUM> from the fourth sub chamber <NUM> to the fourth chamber <NUM>, from being introduced into the third sub chamber <NUM>. Since the fourth sub chamber <NUM> is smaller than the third sub chamber <NUM> in volume, the present disclosure can reduce a time for forming the sub chamber in the nitrogen atmosphere to discharge the mold assembly <NUM> and an amount of nitrogen to be used.

As described above, according to the present disclosure, by using two sub chambers having different volumes, a processing time of press molding can be shortened and the amount of nitrogen used during the processing can be reduced.

On the other hand, the present disclosure minimizes an impact applied to the mold during press molding. To this end, the present disclosure utilizes a transferring element for minimizing the impact applied to the mold when moving the mold.

Hereinafter, a method of moving a mold assembly between chambers will be described.

<FIG> is a conceptual view illustrating a method of moving a mold assembly between chambers, <FIG> is a conceptual view illustrating a bottom surface of a chamber, <FIG> is a conceptual view illustrating a partition wall formed between chambers, and <FIG> is a conceptual view illustrating an operation of moving a mold assembly to another chamber through a partition wall.

Referring to <FIG>, a step of moving the mold assembly <NUM> from one of the first to fourth chambers to another chamber may include moving a transferring bar <NUM> disposed below the one chamber into the one chamber to lift the mold assembly <NUM> from the bottom of the mold assembly <NUM>, horizontally moving the transferring bar <NUM> to the another chamber in a state where the transferring bar <NUM> is lifting the mold assembly <NUM>, and putting the mold assembly <NUM> down on a bottom surface of the another chamber while moving the transferring bar <NUM> to the bottom of the another chamber.

Here, the transferring bar <NUM> which is disposed below a chamber is moved to an upper side of the chamber, so as to lift the mold assembly <NUM>. As illustrated in <FIG>, a hole <NUM> may be formed through a bottom surface <NUM> of a chamber to allow the transferring bar <NUM> to pass therethrough. The hole <NUM> is formed to be large enough for the transferring bar <NUM> to pass therethrough, so as to minimize the loss of heat in the chamber to outside.

The transferring bar <NUM> may be implemented by two bars to stably lift the mold assembly <NUM>. The hole <NUM> may be formed through the bottom surface <NUM> of the chamber as many as the number of bars implementing the transferring bar <NUM>.

The transferring bar <NUM> lifts the mold assembly <NUM> through the holes <NUM> and then horizontally moves along the holes <NUM>. In this way, the present disclosure does not apply a force to the mold assembly <NUM> itself when horizontally moving the mold assembly <NUM>, thereby minimizing an impact applied to the mold assembly <NUM> during movement between chambers.

Meanwhile, the transferring bar <NUM> passes through a partition wall <NUM> disposed between two chambers while lifting the mold assembly <NUM>. Here, the partition wall <NUM> may be disposed between the two chambers to maintain insulation between the two chambers, and to make internal temperature of the chambers uniform.

As illustrated in <FIG>, the partition wall <NUM> may include an upper partition wall <NUM> and a lower partition wall <NUM>. Here, the upper partition wall <NUM> serves to open and close the partition wall through vertical movement, and the lower partition wall <NUM> may be disposed in a fixed state. A hole <NUM> may be formed through the lower partition wall <NUM> to allow the transferring bar <NUM> to move horizontally. The transferring bar <NUM> may move between chambers through the hole <NUM> formed through the lower partition wall <NUM>.

In detail, as illustrated in <FIG>, when the transferring bar <NUM> lifts the mold assembly <NUM>, the partition wall is opened as the upper partition wall <NUM> moves to an upper side of a chamber. Here, the transferring bar <NUM> lifts the mold assembly <NUM> up to a height of the lower partition wall <NUM> so that the mold assembly <NUM> can move to another chamber over the lower partition wall <NUM>.

As described above, the present disclosure minimizes a force applied to the mold assembly when moving the mold assembly from one chamber to another chamber, thereby minimizing deformation of the mold assembly during movement and preventing an impact applied to the mold assembly from being transferred to the glass.

Meanwhile, the present disclosure allows heat to be uniformly transferred all over the mold assembly when the mold assembly is heated. Hereinafter, a manufacturing method for uniformly transferring heat all over a mold assembly in a chamber will be described.

<FIG> is a conceptual view illustrating a cross-section of a hot plate in accordance with the present disclosure.

Referring to <FIG>, the upper hot plate and the lower hot plate (hereinafter, the first hot plate <NUM>) may include an insulating material <NUM>,.

a heating portion <NUM> in which temperature increases as a current flows, and a heat transfer layer <NUM> covering the heating portion <NUM>.

Heat generated in the heating portion <NUM> may differ depending on an area. This is because the current flow in the heating unit <NUM> is not uniform in all areas. When the mold is in direct contact with the heating portion <NUM>, heat may be unevenly transferred to the mold for the aforementioned reason. The heat transfer layer <NUM> evenly spreads the heat generated in the heating portion <NUM> so that heat can be uniformly transferred to the entire mold.

Meanwhile, since great pressure may be applied to the first hot plate <NUM> during the glass molding process, when the mold comes in contact with the heating portion <NUM>, the heating portion <NUM> may be deformed. The heat transfer layer <NUM> serves to prevent the heating portion <NUM> from being deformed due to external pressure.

In addition, the heating portion <NUM> made of a metal material may be oxidized when exposed to high temperature. The heat transfer layer <NUM> serves to prevent the oxidation of the heating portion <NUM>.

For example, the heat transfer layer <NUM> may be made of any one of graphite, anti-oxidation coated graphite, and a ceramic material.

Meanwhile, the thickness of the heat transfer layer <NUM> relative to the width of the first hot plate <NUM> may be in the range of <NUM> to <NUM>. When the thickness of the heat transfer layer <NUM> relative to the width of the first hot plate <NUM> is smaller than <NUM>, the heat transfer layer <NUM> may be destroyed due to pressure applied during the glass molding. On the other hand, when the thickness exceeds <NUM>, a gap between the heating portion <NUM> and the mold may increase so as to lower thermal efficiency.

By utilizing the first hot plate, the deformation of the hot plate during glass molding can be prevented, and uniform heat transfer all over the mold can be achieved.

Meanwhile, as described above, a second hot plate different from the first hot plate may be disposed on side surfaces of the first to third chambers.

Since the second hot plate does not actually come in contact with the mold during the glass molding, the second hot plate is not exposed to high pressure and uniform heat transfer all over the surface of the mold is not required. Therefore, unlike the first hot plate, in the second hot plate, the heating portion does not have to be covered with the heat transfer layer.

The second hot plate is utilized to heat the side surface of the mold assembly to solve thermal imbalance that may occur when heating the mold assembly with the upper and lower hot plates. Since the second hot plate does not come in contact with the mold, the second hot plate may be heated to a higher temperature than the first hot plate. That is, the temperature of the second hot plates disposed in each of the first to third chambers is higher than the temperature of the first hot plates disposed in each of the first to third chambers.

Claim 1:
A method for manufacturing curved glass, the method comprising:
preparing a mold assembly (<NUM>) by stacking a lower mold (<NUM>), a glass part that has a flat shape, and an upper mold (<NUM>), the mold assembly (<NUM>) comprising an elastic member (<NUM>) that is disposed between the lower mold (<NUM>) and the upper mold (<NUM>) defining a space between the upper mold (<NUM>) and the glass part;
placing the mold assembly (<NUM>) in a first chamber (<NUM>), and heating the mold assembly (<NUM>) in the first chamber (<NUM>);
moving the mold assembly (<NUM>) from the first chamber (<NUM>) to a second chamber (<NUM>), and pressurizing the upper mold (<NUM>) and the elastic member (<NUM>) downward to the lower mold (<NUM>) in the second chamber (<NUM>) to mold the glass part into a curved shape;
moving the mold assembly (<NUM>) from the second chamber (<NUM>) to a third chamber (<NUM>), and cooling the glass part in the third chamber (<NUM>); and
moving the mold assembly (<NUM>) from the third chamber (<NUM>) to a fourth chamber (<NUM>), and cooling the glass part in the fourth chamber (<NUM>),
characterized in that each of the first chamber (<NUM>), the second chamber (<NUM>), and the third chamber (<NUM>) comprises a first hot plate (<NUM>) comprising:
a heating portion (<NUM>) configured to contact each of an upper side of the upper mold (<NUM>) and a lower side of the lower mold (<NUM>) and to change a temperature of the mold assembly (<NUM>) based on electric current; and
a heat transfer layer (<NUM>) that covers the heating portion (<NUM>), and
wherein the heat transfer layer (<NUM>) is configured to evenly spread the heat generated in the heating portion (<NUM>) so that heat can be uniformly transferred to the entire mold,
wherein heating the mold assembly (<NUM>) in the first chamber (<NUM>) comprises:
bringing the first hot plate (<NUM>) located in the first chamber (<NUM>) into contact with each of the upper side of the upper mold (<NUM>) and the lower side of the lower mold (<NUM>).