A hot embossing device and a hot embossing method

Abstract

The present invention belongs to the technical field of amorphous material equipment, and particularly relates to a hot embossing device and a hot embossing method. The hot embossing device includes: a heating furnace having a heating chamber and used for heating amorphous materials, a die holder located in the heating chamber, a lower die provided with micro-nano structures, a gravity component, and an upper die cooperating with the lower die. The die holder, the lower die, the upper die, and the gravity component are stacked layer by layer from bottom to top. The lower die is provided with an upward-facing embossing surface, the embossing surface is horizontally arranged and provided with micro-nano structures, the amorphous material is located between the lower die and the upper die and abuts against the micro-nano structures, and the gravity component is stacked on the upper die to press the lower die downward. The present invention simplifies the structure of the hot embossing device, and relative sliding is allowed between the contact surfaces of any two adjacent components, so that deformation caused by connection can be reduced, thereby improving the hot embossing accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of amorphous material forming equipment, and particularly relates to a hot embossing device and a hot embossing method. Background Art

[0002] At present, amorphous materials such as glass, plastics, and amorphous alloys have been widely used in the fields of national defense, industry, and civil use. The demand for functional micro-nano structure devices such as micro-optical elements, microfluidic chips, micro-electro-mechanical system devices, and superhydrophobic surfaces made of these amorphous materials is increasing in the fields of information and communication technology, high-end manufacturing and measurement systems, and biomedicine. Laser direct writing technology, ion beam lithography technology, ultraviolet lithography technology, micro-milling technology, ultra-precision grinding technology, and hot embossing technology can all be used to process functional micro-nano structures on the surface of amorphous materials. Among them, the hot embossing technology has the advantages of high surface replication fidelity, high manufacturing efficiency, high material utilization rate, high flexibility in process modification, etc., and can combine with ultra-precision mold processing technology to achieve the rapid and low-cost manufacture of amorphous material functional micro-nano structure devices with ultra-high surface quality.

[0003] Since the hot embossing technology was proposed in 1995, after extensive research by scholars and engineers, it has developed into a mature replication process. The hot embossing process usually includes four steps: heating the blank to the embossing temperature, embossing the microstructure on the blank, cooling the product to the demolding temperature, and separating the product from the mold. The traditional hot embossing method drives the movement of the upper mold and the lower mold by starting a motor, a cylinder, or a hydraulic cylinder during the embossing stage, so as to apply a load on the blank. To prevent the mold from oxidizing at high temperature, the hot embossing process is usually carried out in a vacuum or inert gas atmosphere.

[0004] Therefore, when designing a hot embossing device, it is necessary to consider the cooling and vacuum sealing problems of the kinematic pairs, which will lead to the complication of the structure of the hot embossing device and the reduction of the molding accuracy. Summary of the Invention

[0005] The purpose of the embodiments of the present application is to provide a hot embossing device, aiming to solve the problems of how to simplify the structure of the hot embossing device and improve the molding accuracy.

[0006] To achieve the above object, the technical solution adopted in this application is as follows: A hot embossing device is provided for embossing amorphous materials. The hot embossing device includes: a heating furnace having a heating chamber and used for heating the amorphous materials, a mold base located in the heating chamber, a lower mold provided with micro-nano structures, a gravity component, and an upper mold cooperating with the lower mold. The mold base, the lower mold, the upper mold, and the gravity component are stacked layer by layer from bottom to top. The lower mold is provided with an upward-facing embossing surface, the embossing surface is horizontally arranged and provided with the micro-nano structures, the amorphous material is located between the lower mold and the upper mold and abuts against the micro-nano structures, and the gravity component is stacked on the upper mold to press the upper mold against the lower mold.

[0007] In one embodiment, the gravity component includes a molten silicon plate stacked on the upper mold and a pressing member stacked on the molten silicon plate.

[0008] In one embodiment, the upper mold is provided with a first support surface, the first support surface faces upward and is horizontally arranged, and the molten silicon plate is stacked on the first support surface; the parallelism between the first support surface and the plate surface of the molten silicon plate facing the first support surface is less than 10 arc seconds.

[0009] In one embodiment, the mold base has a downward-facing and horizontally arranged second support surface and an upward-facing and horizontally arranged third support surface. The second support surface abuts against the inner wall of the heating chamber, and the lower mold abuts against the third support surface.

[0010] In one embodiment, the mold base is made of silicon carbide, and both the second support surface and the third support surface are polished.

[0011] In one embodiment, the hot embossing device further includes a heat insulation block. The heat insulation block is arranged in the heating chamber, the mold base is stacked on the heat insulation block, and the third support surface abuts against the heat insulation block.

[0012] In one embodiment, the hot embossing device further includes a vacuum pumping structure for pumping out the gas in the heating chamber.

[0013] In one embodiment, the vacuum pumping structure includes a vacuum pump for pumping out the gas and a vacuum gauge for measuring the vacuum degree in the heating chamber. The vacuum gauge is connected to the heating furnace.

[0014] In one embodiment, the hot embossing device further includes adjusting support feet and a vibration isolation pad laid on the ground. The heating furnace is arranged on the vibration isolation pad through a plurality of adjusting support feet, and the adjusting support feet are used to adjust the position of the heating furnace to make the embossing surface horizontally arranged.

[0015] The present application also provides a hot embossing method for embossing amorphous materials, and the hot embossing method includes the following steps:

[0016] Prepare a heating furnace, a die holder, a lower mold, a gravity component, and an upper mold;

[0017] The heating furnace has a heating chamber and is used to heat the amorphous material, and the die holder is placed in the heating chamber;

[0018] The lower mold is provided with an upward-facing embossing surface, the embossing surface is arranged horizontally and micro-nano structures are formed on the embossing surface;

[0019] Stack the die holder, the lower mold, and the upper mold layer by layer from bottom to top, and the amorphous material is located between the lower mold and the upper mold and abuts against the micro-nano structures;

[0020] Stack the gravity component on the upper mold to press the lower mold by the upper mold.

[0021] The beneficial effects of the present application are as follows: In this embodiment, components such as the die holder, the lower mold, the gravity component, and the upper mold are all pre-determined in position and then stacked layer by layer by gravity. Therefore, the connection between the components is extremely simple, without excessive kinematic pairs and connection pairs, simplifying the structure of the hot embossing device. And relative sliding is allowed between the contact surfaces of any two adjacent components, so the deformation caused by connection can be reduced, thereby improving the hot embossing accuracy. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or exemplary technical descriptions. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 is the structural schematic diagram of the hot embossing device provided by the embodiment of the present application;

[0024] Figure 2 is the change process diagram of temperature and load during the hot embossing process of the hot embossing method provided by the embodiment of the present application;

[0025] Figure 3 is the process flow diagram of the hot embossing method provided by the embodiment of the present application.

[0026] Among them, the reference numerals in the drawings:

[0027] 1. Heating furnace; 2. Weights; 3. Molten silica plate; 21. Gravity component; 4. Upper mold; 5. Amorphous material; 6. Lower mold; 7. Mold base; 8. Heat insulation block; 9. Control box; 10. Adjusting support feet; 11. Vibration isolation pad; 12. Ground; 15. Heating chamber; 13. Thermocouple; 14. Vacuum gauge; Detailed implementation manners

[0028] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present application.

[0029] It should be noted that when a component is referred to as "fixed to" or "arranged on" another component, it can be directly on the other component or indirectly on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component. The orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present application. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances. Terms "first" and "second" are only used for the purpose of convenient description and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of technical features. The meaning of "a plurality" is two or more, unless otherwise clearly and specifically defined.

[0030] Please refer to Figure 1, embodiments of the present application provide a hot embossing device for embossing amorphous materials 5. Optionally, the amorphous materials include glass, plastic, and amorphous alloy 5. Optionally, in this embodiment, the amorphous material is amorphous alloy 5. Amorphous alloy 5 is obtained by ultra-rapid solidification. When the alloy solidifies, atoms do not have time to arrange and crystallize in an orderly manner. The resulting solid alloy has a long-range disordered structure. The molecules (or atoms, ions) that make up it do not exhibit a regular periodicity in space, and there are no grains and grain boundaries of crystalline alloys. The hot embossing device includes: a heating furnace 1 having a heating chamber 15 and used for heating amorphous alloy 5, a die holder 7 located in the heating chamber 15, a lower die 6 provided with micro-nano structures, a gravity component 21, and an upper die 4 that cooperates with the lower die 6. The die holder 7, the lower die 6, the upper die 4, and the gravity component 21 are stacked on top of each other from bottom to top. Optionally, the die holder 7, the lower die 6, the upper die 4, and the gravity component 21 are stacked together only under the action of gravity, without other kinematic pairs and connection pairs. Therefore, the connection structure is extremely simple; and adjacent two components are allowed to slide a predetermined distance along the connection surface, so that deformation of components caused by connection can be reduced, thereby improving the hot embossing accuracy. Optionally, the lower die 6 is provided with an upward-facing embossing surface, and the embossing surface is horizontally arranged and provided with micro-nano structures. Optionally, the micro-nano structures can be array micro-structures with a size in the micron range or array micro-structures with a size in the nano range, or a combination of both. The amorphous alloy 5 is located between the lower die 6 and the upper die 4 and abuts against the micro-nano structures. The gravity component 21 is stacked on the upper die 4 to press the upper die 4 against the lower die 6. The amorphous alloy 5 is heated to its supercooled liquid phase region by the heating furnace 1, and then an imprinting force is applied to the amorphous alloy 5 by relying on the total weight of the upper die 4 and the gravity component 21. Optionally, the heating furnace 1 has infrared lamps disposed in the heating chamber 15, and the infrared lamps heat the amorphous alloy by infrared radiation.

[0031] Please refer to Figure 1 , optionally, components such as the die holder 7, the lower die 6, the upper die 4, and the gravity component 21 in this embodiment are all pre-determined in position and then stacked layer by layer by gravity. Therefore, the connection between the components is extremely simple, without excessive kinematic pairs and connection pairs. And relative sliding is allowed between the contact surfaces of any two adjacent components, so that deformation caused by connection can be reduced, thereby improving the hot embossing accuracy.

[0032] Optionally, the relative movement between the upper die 4 and the lower die 6 is achieved through the viscoelastic deformation of glass under high temperature and gravity loads. Neither the lower die 6 nor the upper die 4 is connected to other transmission shafts, avoiding problems such as cooling of kinematic pairs and vacuum sealing at the joints of the transmission shafts and the heating chamber 15, thereby simplifying the structure of the hot embossing device.

[0033] Please refer to Figure 1, optionally, in this embodiment, the upper mold 4 and the gravity component 21 are pre-loaded on the amorphous alloy 5 before the amorphous alloy 5 is heated, and then the amorphous alloy 5 is heated by the heating furnace 1. Thus, at the beginning stage when the temperature of the amorphous alloy 5 rises, an imprinting force is applied to the amorphous alloy 5, which is beneficial to fully replicate the micro-nano structure to the amorphous alloy 5 and improve the precision of hot embossing.

[0034] Please refer to Figure 1 , in one embodiment, the gravity component 21 includes a molten silicon plate 3 stacked on the upper mold 4 and a pressing member stacked on the molten silicon plate 3. Optionally, the pressing member is a weight 2. It can be understood that there are multiple weights 2 and the masses of the weights 2 are different from each other, so that different weights 2 can be selected according to different hot embossing requirements.

[0035] Please refer to Figure 1 , in one embodiment, the upper mold 4 is provided with a first support surface which faces upward and is horizontally arranged, and the molten silicon plate 3 is stacked on the first support surface; the parallelism between the first support surface and the plate surface of the molten silicon plate 3 facing the first support surface is less than 10 arc seconds, so as to ensure the surface quality of the amorphous alloy 5 after hot embossing.

[0036] Please refer to Figure 1 , in one embodiment, the mold base 7 has a second support surface which faces downward and is horizontally arranged and a third support surface which faces upward and is horizontally arranged. The second support surface abuts against the inner wall of the heating chamber 15, and the lower mold 6 abuts against the third support surface. Optionally, the third support surface is flatly arranged, so as to improve the fit between the lower mold 6 and the mold base 7 and prevent the lower mold 6 from being damaged during the molding process.

[0037] Please refer to Figure 1 , in one embodiment, the mold base 7 is made of silicon carbide, and both the second support surface and the third support surface are polished. Through the polishing treatment, the flatness and surface finish of the second support surface and the third support surface are improved, which is beneficial to the stability of the lower mold 6 and prevents the lower mold 6 from being damaged.

[0038] In one embodiment, the hot embossing device further includes a heat insulation block 8. The heat insulation block 8 is arranged in the heating chamber 15, the mold base 7 is stacked on the heat insulation block 8, and the third support surface abuts against the heat insulation block 8. The heat insulation block 8 can block the outward radiation of heat.

[0039] Please refer to Figure 1 , in one embodiment, the hot embossing device further includes a vacuum pumping structure for pumping out the gas in the heating chamber 15. Optionally, the vacuum pumping structure is used to pump out the air in the heating chamber 15 and then fill the heating chamber 15 with an inert gas, so as to protect the amorphous alloy 5 during the hot embossing process.

[0040] Please refer toFigure 1 In one embodiment, the evacuation structure includes a vacuum pump for evacuating gas and a vacuum gauge 14 for measuring the vacuum degree in the heating chamber 15. The vacuum gauge 14 is connected to the heating furnace 1.

[0041] In one embodiment, the hot embossing device further includes a thermocouple 13 for measuring the temperature in the heating chamber 15. Optionally, a K-type thermocouple 13 is used to detect the temperature in the heating chamber 15, and the temperature in the heating chamber 15 is controlled by the programmable precise switch proportional integral differential method (PID).

[0042] In one embodiment, the hot embossing device further includes adjusting support feet 10 and vibration isolation pads 11 laid on the ground 12. The heating furnace 1 is arranged on the vibration isolation pads 11 through a plurality of adjusting support feet 10. The adjusting support feet 10 are used to adjust the position of the heating furnace 1 to make the molding surface horizontally arranged. Optionally, the vibration isolation pads 11 are made of cast iron and are used to reduce and isolate the vibration transmission from the ground 12 to the heating furnace 1.

[0043] In one embodiment, the hot embossing device further includes a control box 9 connected to the bottom of the heating furnace 1 and used to control the heating furnace 1.

[0044] Please refer to Figure 1 , optionally, the mechanical load applied on the amorphous alloy 5 is contributed by the gravity of the upper mold 4, the molten silicon plate 3 and the weights 2. Since the gravity of each component is always perpendicular to the ground 12, before placing the amorphous alloy 5, it is necessary to keep the molding surface of the lower mold base 7 horizontal by checking the calibrated digital level and adjusting the nuts of the leveling adjusting support feet 10.

[0045] Please refer to Figure 1 and Figure 3 , the present invention also provides a hot embossing method, which is implemented by the above-mentioned hot embossing device.

[0046] Please refer to Figure 2 , in one embodiment, the hot embossing method includes the following steps:

[0047] Prepare the heating furnace 1, the mold base 7, the lower mold 6, the gravity component 21 and the upper mold 4;

[0048] The heating furnace 1 has a heating chamber 15 and is used to heat the amorphous alloy 5, and place the mold base 7 in the heating chamber 15;

[0049] The lower mold 6 is provided with an upward-facing molding surface, horizontally arrange the molding surface and form micro-nano structures on the molding surface;

[0050] Stack the mold base 7, the lower mold 6 and the upper mold 4 in layers from bottom to top in sequence. The amorphous alloy 5 is located between the lower mold 6 and the upper mold 4 and abuts against the micro-nano structures;

[0051] Please refer to Figure 2 Figure 2 , stack the gravity component 21 on the upper mold 4 so that the upper mold 4 presses down on the lower mold 6.

[0052] Optionally, the hot embossing method further includes the following steps: prepare a vacuum pumping structure and evacuate the gas in the heating chamber 15 to make the heating chamber 15 reach a predetermined vacuum degree. Optionally, an inert gas can also be filled into the heating chamber 15 to prevent the components from being oxidized at high temperatures. The vacuum pumping structure includes a vacuum pump and a vacuum gauge 14.

[0053] Please refer to Figure 2 Figure 2 , optionally, the embossing force of the hot embossing method proposed by the present invention is applied to the blank from the initial stage, that is, applied to the amorphous alloy 5, rather than only applying compressive stress to the amorphous alloy 5 in the embossing stage.

[0054] Please refer to Figure 2 Figure 2 , according to the temperature change process in the heating chamber 15, the hot embossing process is divided into: initialization, heating and molding 32, heat preservation 33, annealing 34, rapid cooling 35, and demolding six stages. Figure 2 A typical temperature and load change process during hot embossing is provided.

[0055] S1: The lower die base 7, the lower mold 6, the amorphous alloy 5, the upper mold 4, the molten silicon plate 3 and the standard weight 2 are gently placed in the predetermined positions, and an embossing force F is applied to the amorphous alloy. The maximum embossing force F is applied in the initial stage w . In order to protect all components in the heating chamber 15 from being oxidized, the heating chamber 15 is sealed and the internal air is discharged by the vacuum pump.

[0056] S2: When the vacuum gauge 14 shows that the vacuum pressure in the heating chamber 15 reaches 10 Pa; the temperature in the heating chamber 15 is increased at a predetermined heating rate r, and the heating furnace 1 is heated from room temperature T0 to the target embossing temperature T2 at a rate of r1;

[0057] S3: Molding time t, in the heat preservation step, the amorphous alloy 5 enters a heat preservation stage with a duration of Δt 23 of the heat preservation stage.

[0058] S4: In the annealing stage, all components in the heating furnace 1 are cooled at a low rate of r3.

[0059] S5: When the temperature in the heating chamber 15 drops to the rapid cooling point T4, the cooling rate rises to r4.

[0060] S6: When the heating chamber 15 is finally cooled to a low enough temperature T B , and after stabilizing for 30 seconds at this temperature, the weight, the molten silicon plate 3, the upper mold 4 and the hot embossed amorphous alloy 5 are manually taken out to achieve demolding.

[0061] As can be seen from Figure 2 it, during the stages from t1 to t4, the pressure F remains constant, while the temperature T first gradually increases and then gradually decreases.

[0062] The above are only optional embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A hot embossing device for embossing amorphous materials, characterized in that The hot embossing device includes: a heating furnace having a heating chamber and for heating the amorphous material, a die holder located in the heating chamber, a lower mold provided with a micro-nano structure, a gravity assembly, and an upper mold cooperating with the lower mold. The die holder, the lower mold, the upper mold, and the gravity assembly are stacked in sequence from bottom to top only under the action of gravity, and relative sliding is allowed between adjacent two components along the connecting surface. The lower mold is provided with an upward-facing embossing surface, the embossing surface is horizontally arranged and provided with the micro-nano structure, the amorphous material is located between the lower mold and the upper mold and abuts against the micro-nano structure, and the gravity assembly is stacked on the upper mold to press the lower mold downwards. The gravity assembly includes a molten silicon plate stacked on the upper mold and a pressing member stacked on the molten silicon plate. The upper mold is provided with a first support surface, the first support surface faces upwards and is horizontally arranged, and the molten silicon plate is stacked on the first support surface. The parallelism between the first support surface and the plate surface of the molten silicon plate facing the first support surface is less than 10 arc seconds. The die holder has a downward-facing and horizontally arranged second support surface and an upward-facing and horizontally arranged third support surface. The second support surface abuts against the inner wall of the heating chamber, and the lower mold abuts against the third support surface. The die holder is made of silicon carbide, and both the second support surface and the third support surface are polished to improve the flatness and surface finish of the second support surface and the third support surface.

2. The hot embossing device according to claim 1, wherein: The hot embossing device further includes a heat insulation block. The heat insulation block is arranged in the heating chamber, the die holder is stacked on the heat insulation block, and the third support surface abuts against the heat insulation block.

3. The hot embossing device according to any one of claims 1-2, characterized in that: The hot embossing device further includes a vacuum pumping structure for pumping out the gas in the heating chamber.

4. The hot embossing device according to claim 3, wherein: The vacuum pumping structure includes a vacuum pump for pumping out the gas and a vacuum gauge for measuring the vacuum degree in the heating chamber. The vacuum gauge is connected to the heating furnace.

5. The hot embossing device according to any one of claims 1-2, characterized in that: The hot embossing device further includes adjusting support feet and a vibration isolation pad laid on the ground. The heating furnace is arranged on the vibration isolation pad through a plurality of adjusting support feet, and the adjusting support feet are used to adjust the position of the heating furnace to make the embossing surface horizontally arranged.

6. A hot embossing method, characterized in that, Using the hot embossing device according to any one of claims 1-5 to emboss an amorphous material includes the following steps: Prepare a heating furnace, a die holder, a lower mold, a gravity assembly, and an upper mold. The heating furnace has a heating chamber and is used to heat the amorphous material. Place the die holder in the heating chamber. The lower mold is provided with an upward-facing embossing surface. Horizontally arrange the embossing surface and form a micro-nano structure on the embossing surface. Stack the die holder, the lower mold, and the upper mold in sequence from bottom to top only under the action of gravity, and allow relative sliding between adjacent two components along the connecting surface. The amorphous material is located between the lower mold and the upper mold and abuts against the micro-nano structure. Stack the gravity component on the upper mold so that the upper mold presses down on the lower mold; the upper mold and the gravity component are pre-loaded on the amorphous material before the amorphous material is heated, and then the amorphous material is heated by the heating furnace, so that an imprinting force is applied to the amorphous material at the beginning stage when the temperature of the amorphous material rises.

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