Thermoforming method and thermoforming device for glass product

The present disclosure provides a thermoforming method and a thermoforming device for a glass product. The method comprises the following steps of: providing a thermoforming mold, wherein the thermoforming mold comprises a lower mold and an upper mold arranged above the lower mold and matched therewith, and providing a mold opening component; a pressurizing process, wherein a glass sheet placed in the thermoforming mold and at a softening point temperature and above is hot-pressed to form a glass product; a cooling process, wherein the glass product placed in the thermoforming mold is cooled, and when the temperature of the glass product drops to a glass point transformation temperature and below, the upper mold is opened by the mold opening component so that the upper mold is separated from the lower mold; and taking the glass product out when the temperature of the glass product in the thermoforming mold drops to a room temperature. The thermoforming method improves the molding quality of the glass product and enhances the manufacturing yield of the glass product.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Chinese Patent Applications Ser. No. 201711143561.7 filed on Nov. 17, 2017, the entire content of which is incorporated herein by reference.

FIELD OF THE PRESENT DISCLOSURE

The present disclosure relates to the technical field of glass product molding, and more particularly, to a thermoforming method and a thermoforming device for a glass product.

DESCRIPTION OF RELATED ART

A glass product is bent and molded by a thermoforming device. When the glass product is thermoformed, a glass sheet is put into a thermoforming mold firstly, and the glass sheet moves to a molding chamber along with the thermoforming mold. The glass sheet is gradually heated through a plurality of heating stations, and a temperature of the glass sheet is gradually increased from a room temperature T0to a softening point temperature T3. In the warm-up preheating stage, the thermoforming mold does not apply pressure to the glass sheet.

When the glass sheet is completely preheated and reaches the softening point temperature T3, the glass sheet is transported to each pressurizing station. The pressurizing station applies a pressure to an upper mold by a cylinder or a motor, and the upper mold is held down by the pressure so that the upper mold moves downwards, and the upper mold and a lower mold of the thermoforming mold are clamped, and the glass sheet is bent and deformed. A plurality of pressurizing stations can be provided. The glass sequentially passes through the pressurizing stations and is gradually pressed and molded.

After being hot-bent and molded, the glass sheet also needs to be cooled. At this time, the hot-bent glass product is transported to the cooling stations. After passing through two (or more) cooling stations, the temperature of the glass product decreases and approaches to the room temperature T0, the thermoforming mold moves to the outside of the cooling station, and the mold is opened to take the molded glass product out from a hot bending machine, and the hot bending process of the glass product is ended.

However, since the materials used for the thermoforming mold are usually materials such as graphite, metals, and ceramics, the thermal expansion coefficients of the above-mentioned materials are different from that of the glass material, and there are differences in the shrinkage rates of different materials when the materials are cooled in the cooling station, the glass product has the risk of bursting or fracturing, especially when the glass product has a large bending angle or a complex shape, the risk of cracking increases significantly. In addition, due to factors such as gravity of the thermoforming mold itself, the size of the glass product will also change, thereby reducing the manufacturing yield of the glass product.

REFERENCE NUMERALS

The accompanying drawings herein are incorporated in and constitute a part of this description, illustrate the embodiments in conformity with the disclosure, and serve to explain the principles of the disclosure together with the description.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The disclosure will be further described in detail below through specific embodiments and with reference to the accompanying drawings.

As shown inFIGS. 1 to 2, the present disclosure provides a thermoforming method for a glass product. The thermoforming of the glass product needs to be equipped with a thermoforming mold2, and the thermoforming mold2comprises a lower mold204(for example, a male mold) and an upper mold202(for example, a female mold) matched therewith. The lower mold204and the upper mold202are matched to form a cavity for molding the glass product.

The thermoforming method comprises a heating process, a pressurizing process, and a cooling process. In the thermoforming process of the glass product, the thermoforming mold2carries a glass sheet to sequentially move in the heating process, the pressurizing process, and the cooling process. The glass sheet is placed on the lower mold204usually.

Specifically, in the heating process, the glass sheet placed on the lower mold204of the thermoforming mold2can be heated so that the temperature of the glass sheet gradually rises from an initial temperature (room temperature) to a softening point temperature, thereby providing the glass sheet to be processed reaching the softening point temperature and above.

Alternatively, the heating process may further comprise a preheating stage and a heating stage. In the preheating stage, the glass sheet reaches the preheating temperature from the room temperature. In the heating stage, the glass sheet reaches the softening point temperature from the preheating temperature. The heating method can ensure that the glass sheet is sufficiently heated and the temperature of various portions of the glass sheet is relatively balanced to reduce the temperature difference.

When the glass sheet reaches the softening point temperature, it is transferred to the pressurizing process. In the pressurizing process, the upper mold202located above the lower mold204is matched with the lower mold204to apply a pressure to the glass sheet, so as to mold the glass sheet. The molded glass sheet becomes a glass product that can be used as a product accessory, such as a mobile phone glass screen, etc.

After pressurizing and molding, the glass product enters the cooling process. In the cooling process, the glass product is cooled. When the temperature of the glass sheet is reduced to a glass point transformation temperature and below, the glass product is cured and can maintain a stable form. At this time, a mold opening component may be provided. The upper mold202is opened by the mold opening component, so that the upper mold202and the lower mold204are separated. After the two molds are separated, the glass product is exposed from the thermoforming mold2, and the glass product will not be limited by the upper mold202when shrinking and deforming. Therefore, the glass product no longer interferes with the upper mold202, thus reducing the risk of cracking of the glass product in the cooling process, thereby improving the quality of the glass product and enhancing the manufacturing yield of the glass product.

When the glass product is continuously cooled to the room temperature, the thermoforming mold2carrying the glass product is conveyed from the inside of a molding chamber to the outside of the molding room. At this time, the glass product may be taken out from the lower mold204of the thermoforming mold2.

When the upper mold202is opened, in order to prevent the upper mold202from being difficult to open due to the adhesion of the glass product with the upper mold202, the thermoforming mold2may further comprises a pressing block, and the pressing block applies a downward pressure to the glass product. The glass product is tightly pressed by the pressing block, so that the glass product will not be adhered with the upper mold202and will smoothly fall onto the lower mold204.

Alternatively, the cooling process may further comprise a first cooling stage and a second cooling stage, wherein the glass product is cooled from the softening point temperature to an intermediate temperature in the first cooling stage, and the glass product is cooled from the intermediate temperature to the room temperature in the second cooling stage.

In order to reduce the defects of the glass product during cooling, an optional solution is to slowly cool the glass product at the beginning of the cooling process, i.e., the first cooling stage, so as to reduce the deformation of the glass product during the cooling process and avoid large size deviation of the molded glass product. After the deformation of the glass product is stabilized, the second cooling stage can be entered. At this time, the glass product can be cooled at a cooling rate more than the cooling rate of the first cooling stage.

Wherein, the glass product may be cooled to the glass point transformation temperature in the first cooling stage, or the glass product may be cooled to the glass point transformation temperature in the second cooling stage.

The “slow cooling” herein refers to cooling at a rate less than a certain cooling rate, and those skilled in the art can make reasonable choices based on the composition of the glass product.

Further, as shown inFIG. 3, in the cooling process, after the upper mold202is opened, the lower mold204carrying the glass product may also be moved by a preset distance δ along a horizontal direction. At this time, the upper mold202and the lower mold204are dislocated. Since a long time is needed for the cooling process, the upper mold202may be reset from an aspect of safety, so that the upper mold202is dislocatedly supported on the lower mold204to prevent the upper mold202from falling.

Specifically, in the embodiment as shown inFIG. 3, the lower mold204is provided with a vertical post2042, and the upper mold202is provided with a through hole that is located opposite to the position of the vertical post2042. When the upper mold202and the lower mold204are clamped together, the vertical post2042is inserted into the through hole. When the upper mold202and the lower mold204are dislocated, the upper mold202is supported on the vertical post2042. At this time, the vertical post2042serves as a support post that supports the upper mold202, so as to implement the dislocated support of the lower mold204on the upper mold202.

It is easy to understand that since the upper mold202and the lower mold204are in a dislocated state, even if the upper mold202is reset, the upper mold202will not come into contact with the glass product.

In the thermoforming method provided by the present disclosure, in order to ensure the continuity of the thermoforming process and enhance the thermoforming efficiency, an assembly line operation is generally adopted for the thermoforming of the glass product, and the thermoforming mold2is flowed in each process in a stepping manner and the stepping distances between the processes are usually set to be equal.

In the foregoing solution, if the lower mold204has already been moved by a preset distance along the horizontal direction, position deviation may occur when the thermoforming mold2is flowed to next process at a preset stepping distance. Therefore, after the upper mold202is supported on the lower mold204, the lower mold204may be reset so that the lower mold204and the upper mold202that are dislocated are moved back to a position of the lower mold204before being moved, so that it is still possible to move according to the preset stepping distance when stepping to next process, and it is possible to ensure that the thermoforming mold2is moved to an accurate position, thereby avoiding position deviation during the flow of the thermoforming mold2.

Further, in the thermoforming process, an ejection member may further be provided. In the cooling process, after the upper mold202is opened, an acting force may be applied to the glass product by the ejection member so that the glass product and the lower mold204are relatively displaced. However, it should be noted that the glass product may be incompletely separated from the lower mold204.

The “incomplete separation” mentioned herein refers to a case in which the glass product is still in contact with the lower mold204, but adhesion does not occur between the two.

By an ejecting force exerted by the ejection member on the glass product, a gap may be left between the glass product and the lower mold204. The gap may prevent the glass product from being limited by the lower mold204when shrinking, and avoid the glass product from being interfered with the lower mold204, thus further reducing the risk of cracking of the glass product.

Based on the above-mentioned thermoforming method for a glass product, the present disclosure further provides a thermoforming device100for a glass product. The thermoforming device100uses the thermoforming method described in any of the above embodiments to mold a glass product.

As shown inFIG. 4, the thermoforming device100comprises a heating station4, a pressurizing station6, a cooling station8and the thermoforming mold2in any one of the above embodiments. The thermoforming mold2comprises a lower mold204and an upper mold202arranged above the lower mold204and matched therewith. The thermoforming mold2carries a glass sheet to sequentially pass through the heating station4, the pressurizing station6, and the cooling station8to achieve heating, pressurizing and forming, and cooling of the glass sheet.

Specifically, the heating station4is configured to heat the glass sheet at a softening point temperature and above. The pressurizing station6applies a pressure to the glass sheet at the softening point temperature and above by the thermoforming mold2to mold the glass sheet into a glass product. The cooling station8is configured to cool the temperature of the glass product to a glass point transformation temperature and below and finally to a room temperature.

Specifically, as shown inFIGS. 5 to 10, thermoforming device100further comprises a mold opening component10, the mold opening component10has a movement stroke, and the mold opening component10is arranged to be capable of opening the upper mold202in the movement stroke. When the upper mold202is opened, the temperature of the glass product should drop to the glass point transformation temperature and below.

After the upper mold202is opened by the mold opening component10, the glass product is exposed from the thermoforming mold2and is continuously cooled. During the cooling process, the glass product will not be limited by the upper mold202, then the cracking rate of the glass product is reduced, and the manufacturing yield of the glass product is enhanced.

The mold opening component10has various embodiments. Referring toFIG. 5and Figure, an embodiment of the mold opening component10comprises a driving portion (not shown in the figures) and a force applying portion102. The driving portion is in drive connection with the force applying portion102. The driving portion serves as an actuating member. The force applying portion102serves as_an intermediate connector for being contacted with the upper mold202. The driving portion applies an acting force to the upper mold202via the force applying portion102.

In some embodiments, the driving portion may be an air cylinder, a hydraulic cylinder, a motor, etc. In some other embodiments, the driving portion may also be an elastic mechanism, which is not limited in the present disclosure.

Please refer toFIG. 5continuously. The upper mold202is provided with a connecting trough2022, and the force applying portion102is a rod-shaped structure. The force applying portion102can be respectively located in two positions. One position is a placed position when the force applying portion102is placed into the connecting trough2022(seeFIG. 5), and the other position is that a working position where the force applying portion102applies an acting force to the upper mold202and separates the upper mold202from the lower mold204(seeFIG. 6). In a plane perpendicular to a force application action line of the force applying portion102, the placed position is at an angle to the working position. The force applying portion102can apply an acting force to the upper mold202at the working position, and under the acting force, the upper mold202is separated from the lower mold204.

It can be seen fromFIG. 6that one end of the force applying portion102is a T-shaped end. When the force applying portion102is in the placed position, the size of an opening of the connecting trough2022allows to place in a horizontal segment of the T-shaped end. At this time, the horizontal segment of the T-shaped end is placed in the connecting trough2022. Then, the force applying portion102is rotated to a preset angle, such as 30 degrees, 60 degrees, or 90 degrees, and a central line of rotation is an axis of a vertical segment of the T-shaped end. At this time, the force applying portion102is at the working position. At the working position, the size of the horizontal segment of the T-shaped end is larger than the size of the opening of the connecting trough2022, and the force applying portion102cannot escape from the opening. At this time, when the driving portion applies an acting force to the upper mold202via the force applying portion102, the upper mold202is opened.

In another embodiment, as shown inFIG. 7, the lower mold204is provided with a through hole2044, and the force applying portion102applies a pushing force to a lower surface of the upper mold204via the through hole2044to open the upper mold202.

In another embodiment, as shown inFIG. 8, the force applying portion102is arranged in a reserved gap between the upper mold202and the lower mold204and has a plate like structure. When the driving portion generates a driving force, the force applying portion102generates a movement stroke. The force applying portion102is in contact with the lower surface of the upper mold202, and drives the upper mold202to be separated from the lower mold204.

In the embodiments as shown inFIG. 7andFIG. 8, the number of the force applying portion102is two to ensure the balance of forces.

In the above embodiments, the structure of the mold opening component10is relatively simple and convenient to implement, and the mold opening component10and the thermoforming mold2do not need to be connected by a fastener, and the mold opening operation is simple and convenient.

As shown inFIG. 9, in some other embodiments, the mold opening component10may further comprises a driving portion and a magnetic mechanism104. The magnetic portion104is effectively connected with the upper mold202by magnetic attraction, and the magnetic portion104may be a permanent magnet or an electromagnet.

As shown inFIG. 10, the mold opening component10may further comprise a driving part and an adsorption portion106, wherein the adsorption portion106is effectively connected with the upper mold202by vacuum adsorption.

In the embodiments as shown inFIG. 9andFIG. 10, the magnetic portion104and the adsorption portion106may be in direct contact with the upper mold202, and keep connection with the upper mold202by a magnetic force and an adsorption force, which is simpler to implement, and has higher efficient operation than other embodiments.

Moreover, the thermoforming device100provided by the present disclosure further comprises an auxiliary driving portion (not shown in the figures), wherein the auxiliary driving portion is in drive connection with the lower mold204so that the lower mold204is moved by a preset distance along a horizontal direction and is dislocated with the upper mold202.

Further, the thermoforming device100further comprises a holding portion12, for example, the holding portion12in an embodiment is implemented as the vertical post2042inFIG. 3, and is arranged on the lower mold204, and the upper mold202is provided with a through hole corresponding to the vertical post2042. When the upper mold202and the lower mold204are clamped together, the vertical post2042is embedded in the through hole. When the upper mold202and the lower mold204are dislocated from each other, the vertical post2042is no longer facing the through hole, and the vertical post2042is supported on the lower surface of the upper mold202. At this time, the vertical post2042can hold the upper mold202and the lower mold204in an opened state.FIG. 3shows a schematic diagram of holding the upper mold202and the lower mold204that are dislocated in the opened state by the vertical post2042.

In some other embodiments, the holding portion12may be configured as a separate part, such as a cushion block, and the cushion block is attached between the upper mold202and the lower mold204so as to support the upper mold202.

As shown inFIG. 11, assuming that the stepping distance between the pressurizing station6and the cooling station8is L1, the glass sheet is stepped with the thermoforming mold2by the distance L1so as to enter the cooling station8from the pressurizing station6. In the cooling station8, when the temperature of the thermoforming mold2drops to the glass point transformation temperature, the mold opening component10applies an acting force to the upper mold202to open the thermoforming mold2.

After the thermoforming mold2is opened, the lower mold204is driven to step forward by a distance L2by the auxiliary driving portion, so that the upper mold202and the lower mold204are dislocated.

When the upper mold202and the lower mold204are dislocatedly placed, the lower mold204is driven and moved by the distance L2towards the opposite direction of the stepping direction at the moment, i.e., the lower mold204is reset to the position before moving, so that the thermoforming mold can be continuously moved to next station in accordance with the stepping distance L1between the stations.

In addition, the thermoforming device100provided by the present disclosure may further comprise an ejection member (not shown in the figures). The ejection member has an ejection stroke. After the upper mold202is opened in the cooling process, the ejection member may apply an acting force to the glass product, so that the glass product and the lower mold204are displaced.

The ejection member causes a gap between the glass product and the lower mold204, which reduces the interference of the glass product with the lower mold204during shrinking, thereby further improving the molding quality of the glass product and further reducing the risk of cracking. The ejection member may be in contact with the glass product via the through hole arranged in the lower mold204.

The glass product may be incompletely detached from the lower mold204. The “incompletely detached” refers to a case in which the glass product is still in contact with the lower mold204, but the two will not adhere with each other.

The ejection member may be driven by a spring, a motor, a cylinder, a hydraulic cylinder, a nut screw mechanism, etc., and will not be elaborated herein.

Those described above are merely preferred embodiments of the disclosure, but are not intended to limit the disclosure. Any change, equivalent substitution, and improvement made within the spirit and principle of the disclosure shall fall within the protection scope of the disclosure.