Opposed ultrasonic vibration assisted molding device and method

Abstract

The present invention discloses a device and method for assisting in molding with ultrasonic vibrations, which consists of an ultrasonic vibration system, a servo loading system, and a heating system of electric heating rod heating + heat transfer by a heat spreader. The device can simultaneously apply ultrasonic longitudinal vibrations, precise servo loading, and real-time adjustment and control of molding temperature to the upper and lower molds during the molding process. Compared with traditional molding and unidirectional ultrasonic vibration molding methods, the device effectively solves the problems of incomplete molding and easy adhesion between glass and molds for array-type microstructure glass elements with sharp edges and large depth-to-diameter ratios such as compound eye arrays, V-grooves, rectangular grooves, pyramids, and Fresnel rings. Ultrasonic vibration molding that only applies ultrasonic vibrations to the upper mold cannot change the adhesion and flow properties between the glass element and the lower mold, resulting in different friction coefficients between the upper and lower contact surfaces, and leading to differences in the flow conditions of the upper and lower parts of the glass element during molding, resulting in differences in stress, strain, and surface accuracy.

Description

Technical Field

[0001] The invention relates to the field of microstructure glass optical element compression molding, and in particular to a device and method for improving the compression filling rate and demoulding performance of microstructure glass optical elements by directional ultrasonic vibration auxiliary compression molding. Background Art

[0002] In recent years, the optical industry has seen an increasing demand for array glass microstructure surfaces such as microlenses, microgrooves, microcones, and microprisms. Glass optical components with microsurface structures, especially microstructure compound eye array lenses, play an important role in improving the imaging quality of optical systems. With their special geometric characteristics, they can provide a variety of optical functions and better imaging quality. They have become core components in the fields of smart phones, digital cameras, space optical communications, infrared detection, medical equipment, and intelligent guidance systems, and can achieve high-definition, high-resolution, high-uniformity, and beam shaping and expansion imaging, reflection, and diffraction functions.

[0003] The compression molding technology of microstructured glass optical elements has the advantages of high repeatability, no pollution, net forming, low cost, and suitability for mass production. It is considered to be one of the most revolutionary optical manufacturing technologies in the world. Compared with traditional lens manufacturing methods such as fast tool servo single-point diamond turning, femtosecond laser beam, electron beam, plasma beam, LIGA technology, etc., it has the advantages of high production efficiency, diversified processing materials, good processing consistency and process stability. However, for array-type microstructured glass elements with sharp edges and large aspect ratios such as compound eye arrays, V-grooves, rectangular grooves, pyramids, and Fresnel rings, the existing compression molding method has the problem that the flow and deformation of the glass material in the micro-scale mold grooves during the hot pressing process are hindered, resulting in insufficient filling rate of the glass microstructure after molding and reduced product geometric accuracy; the glass-mold contact interface is easy to bond, resulting in difficulty in demolding the filled part of the glass microstructure after molding, causing glass breakage and other problems.

[0004] Ultrasonic vibration-assisted molding introduces an ultrasonic vibration system to apply longitudinal ultrasonic vibration to the molding system on the basis of traditional molding principles. It can improve the filling rate and demolding performance during the molding process and solve the technical problems existing in traditional molding.

[0005] In domestic public disclosures and materials, Hunan University's utility model (patent ZL201420846015.5) provides an ultrasonic vibration precision molding device for complex microstructure optical elements, including a cylinder, a slider and guide rail, a connecting rod, an ultrasonic generator, a transducer, a horn, a heat insulation board, and a heating plate. The application of this device reduces the adhesion and damage of glass elements to the mold surface, and realizes the precision molding of complex microstructure optical elements. However, the device only applies longitudinal ultrasonic vibration to the upper mold, and the effect of improving the molding filling rate and demolding performance is relatively limited. Moreover, it only vibrates on one side of the upper mold, which helps to improve the demolding adhesion between the glass element and the upper mold, but cannot improve the demolding adhesion between the glass element and the lower mold; it only vibrates on one side of the upper mold, which changes the friction coefficient and flow conditions between the glass element and the upper mold, but cannot change the friction coefficient and flow conditions between the glass element and the lower mold, resulting in different friction coefficients of the upper and lower contact surfaces, and causing differences in the flow conditions of the upper and lower parts of the glass element during molding, resulting in differences in stress, strain and surface accuracy. Figure 1 As shown, after applying unidirectional ultrasonic vibration to the upper mold, the filling edge line of the upper mold compound eye lens has not overlapped with the mold contour line, that is, it is not fully filled. Similarly, the filling edge line of the lower mold concave lens has not overlapped with the mold contour line, and the deviation between the two is larger than that of the upper mold. At the same time, the stress at the contact between the lower mold contour line and the filling edge line of the concave lens is greater than the stress at the contact between the upper mold contour line and the filling edge line of the sub-compound eye lens. The molding test shows that the adhesion between the glass and the mold is more obvious at the lower mold. Therefore, it is necessary to apply ultrasonic vibration to the lower mold to improve the filling situation and demolding performance.

[0006] In foreign public information, there are no reports on devices and methods using ultrasonic vibration to assist compression molding, but there are related patents that apply ultrasonic vibration to injection molding of resin materials. The European patent (EP1645381A8) registered by Japan's Hilight Co., Ltd. provides a device and method for using ultrasonic vibration to melt and mold resin materials, feeding the molding material into a mold located at one end of the cylinder to melt and knead the material in the cylinder, and at the same time vibrating the molding material in a direction on the right side so that it intersects with the flow direction of the resin material. The US patent (US5017311A) registered by Toshihiro Furusawa et al. of Japan provides a method for using ultrasonic vibration to improve the fluidity of high molecular weight polymers, and the injection molding equipment has a fixed mold and a movable mold; one side of the movable mold has a cavity, and the other side is connected to an ultrasonic vibration feeding device. The methods provided by the above two patents are limited to injection molding of resin materials. Since glass materials require higher temperatures to soften, have poor fluidity and strong adhesion, and the molding temperature of resin materials is low, the glass is in a molten state during injection molding. The purpose of applying ultrasonic vibration is mainly for demolding, but the purpose of ultrasonic vibration-assisted molding is to improve the filling rate and demolding performance. Therefore, the two are different in molding principles and mechanisms. At the same time, both patents apply ultrasonic vibration in one direction, and there is also a technical defect of only changing the demolding adhesion condition of the lower mold. Summary of the invention

[0007] The present invention aims to overcome the deficiencies of the above-mentioned prior art and provides a device and method for assisted molding by counter-directional ultrasonic vibration, which can solve the following problems during unidirectional ultrasonic molding of complex microstructure optical elements: 1) difficulty in demolding the upper and lower molds, 2) inconsistent flow conditions at the upper and lower parts of the glass element, resulting in uneven stress and strain, uneven surface accuracy, etc., improve the fluidity of the glass material in the micro-scale mold grooves, improve the filling rate and surface accuracy of the microstructure, and improve the demolding difficulties and glass breakage problems.

[0008] To achieve the above object, the technical solution of the present invention is:

[0009] A opposed ultrasonic vibration-assisted molding device comprises a first ultrasonic vibration device and a second ultrasonic vibration device arranged opposite to each other; the first ultrasonic vibration device is connected to a concave lower mold 35; the second ultrasonic vibration device is connected to a convex upper mold 38, and a molding cavity 45 is formed between the concave lower mold 35 and the convex upper mold 38; the first ultrasonic vibration device and the second ultrasonic vibration device are both connected to a heating device; the second ultrasonic vibration device is connected to a lifting device via a pressure sensor 23.

[0010] As a further improvement, the first ultrasonic vibration device includes a first transducer 5, which is connected to a first ultrasonic horn 10; the second ultrasonic vibration device includes a second transducer 10, which is connected to a second ultrasonic horn 30; the first transducer 5 and the second transducer 10 are both sandwich piezoelectric ceramic ultrasonic transducers.

[0011] As a further improvement, the heating device comprises a first heating rod 12 and a second heating rod 34 connected to the first ultrasonic vibration device, and a third heating rod 16 and a fourth heating rod 32 connected to the second ultrasonic vibration device; the first heating rod 12 and the second heating rod 34 are connected to the first ultrasonic vibration device via a first uniform heat transfer platform 14; the third heating rod 16 and the fourth heating rod 32 are connected to the second ultrasonic vibration device via a second uniform heat transfer platform 17; the heating device is a heating rod, and the heating rod is connected to a heating source.

[0012] As a further improvement, the first heating rod 12, the second heating rod 34, the third heating rod 16, the fourth heating rod 32, the concave lower mold 35 and the convex upper mold 38 are all installed in a molding chamber 2 formed by a high-temperature resistant transparent glass plate 3; the lower part of one side of the molding chamber 2 is connected to a molding chamber air inlet 13, and the upper part of the other side is connected to a molding chamber exhaust port 31.

[0013] As a further improvement, the outer cover of the first ultrasonic vibration device is provided with a first ultrasonic vibration device condensation chamber 7, and the outer cover of the second ultrasonic vibration device is provided with a second ultrasonic vibration device condensation chamber 21; the first ultrasonic vibration device condensation chamber 7 is provided with a first ultrasonic vibration device air-cooled air inlet 4 on one side, and a first ultrasonic vibration device condensation chamber air-cooled exhaust port 8 on the other side; the second ultrasonic vibration device condensation chamber 21 is provided with a second ultrasonic vibration device air-cooled air inlet 29 on one side, and a second ultrasonic vibration device condensation chamber air-cooled exhaust port 20 on the other side.

[0014] As a further improvement, an annular groove is formed on the first uniform heat transfer platform 14, and a positioning sleeve 44 is provided in the annular groove. The positioning sleeve 44 is fixedly connected to the first ultrasonic horn 10 and the limiting outer sleeve 37. The limiting outer sleeve 37 is fixed outside the inner sleeve 36. Mold exhaust holes 40 are formed on the positioning inner sleeve 36 and the outer sleeve 37; the molding cavity 45 is located in the inner sleeve 36; a lower mold thermocouple temperature control point 15 is installed between the top of the first ultrasonic horn 10 and the concave lower mold 35; a pressure rod 19 is connected to the bottom of the second ultrasonic horn 30, and an upper mold thermocouple temperature control point 33 is fixed between the pressure rod and the second uniform heat transfer platform 17.

[0015] As a further improvement, a first insulation board 11 is installed between the high temperature resistant transparent glass plate 3 and the first uniform heat transfer platform 14 ; and a second insulation board 18 is installed between the high temperature resistant transparent glass plate 3 and the second uniform heat transfer platform 17 .

[0016] As a further improvement, the lifting device includes a servo motor 26 , the servo motor 26 is connected to a servo electric cylinder 25 , and the servo electric cylinder 25 is connected to a pressure sensor 23 via 24 .

[0017] A method for counter-acting ultrasonic vibration-assisted compression molding, the method comprising the following steps:

[0018] Step 1: Install the glass between the lower mold and the upper mold to form a molding cavity 45; then heat the glass in a nitrogen atmosphere to a temperature above the glass transition point;

[0019] Step 2: Start the lifting device connected to the mold 38 on the convex surface, and collect the downward pressure load for molding. During the molding process, ultrasonic vibration is performed: set the total molding time t z , after the preset time t1 of the molding start, the first ultrasonic vibration device connected to the lower mold is started to apply ultrasonic longitudinal vibration to the lower mold, the vibration frequency range is 30-35KHz, the amplitude range is 8-10μm, and the time is t2, so as to increase the filling rate of the glass in the lower mold; then the second ultrasonic vibration device connected to the upper mold is started to apply ultrasonic longitudinal vibration to the upper mold, the vibration parameters are the same as those of the first ultrasonic vibration device, and the vibration application time is t3, so that the space between the upper and lower molds and the glass is completely filled, and at this time, the ultrasonic vibration time applied to the lower mold is (t2+t3)s; t z =90~120s, t1=20~30s, t2=30~40s, t3=40~50s;

[0020] Step 3, annealing: In the annealing stage, the first ultrasonic vibration device and the second ultrasonic vibration device are turned off, the temperature in the molding cavity is reduced to a preset annealing temperature, and the pressure holding and annealing treatment are performed under the load;

[0021] Step 4: Demolding pretreatment: Secondary cooling for demoulding pretreatment, lowering the temperature in the molding cavity again to the glass transition point temperature T g Below 50±5℃, the first ultrasonic vibration device and the second ultrasonic vibration device are turned on at the same time to perform ultrasonic vibration demoulding pretreatment, at this time, the vibration frequency is kept in the low-frequency vibration frequency range of 15-20KHz, the amplitude range is 2-4μm, and the time is t4, so as to improve the demoulding performance between the optical element and the mold, and then the first and second ultrasonic vibration devices are turned off; t4=20-30s;

[0022] Step 5: Cooling: During the cooling stage, the cold air provided by the chiller is used to lower the temperature of the molding cavity again for cooling. After cooling to room temperature, the mold is taken out to obtain the desired molded optical element.

[0023] The servo motor mentioned above controls the rotary motion through a motion control card, and then converts the motor rotation into the linear motion of the electric cylinder screw through a ball screw pair, providing driving force and displacement for the terminal load. Finally, combined with the real-time acquisition and feedback processing of the sensor pressure signal and the encoder displacement signal, precise closed-loop control of the output driving force, displacement and speed is achieved.

[0024] The ultrasonic transducer is connected to an ultrasonic power supply, and the horn is connected to the ultrasonic transducer. First, a high-frequency alternating electrical signal is generated by the ultrasonic power supply, and then the high-frequency electrical signal is converted into mechanical vibration by the piezoelectric transducer. Finally, the mechanical vibration is amplified by the horn and transmitted to the upper mold, the lower mold and the glass blank respectively, thereby realizing ultrasonic vibration-assisted hot pressing of the glass element.

[0025] The heating temperature or cooling temperature of the mold and glass is detected in real time through the thermocouple temperature control point, and the temperature signal is transmitted to the temperature controller to control the heating temperature of the heating source or the cooling system to heat up or cool down in real time, so as to control the temperature at the required temperature value.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present technical invention provides a device and method for assisted molding by opposed ultrasonic vibrations. The device consists of an opposed ultrasonic vibration system, a servo loading system, and a heating system of electric heating rod heating + heat transfer by a heat spreader. It can realize simultaneous application of ultrasonic longitudinal vibrations, precise servo loading, and real-time adjustment and control of the molding temperature to the upper and lower molds during the molding process. Compared with traditional precision molding and existing unidirectional ultrasonic vibration molding methods, the molding process method using counter-directional ultrasonic vibration assisted molding device and segmented application of ultrasonic vibration effectively solves the problems of incomplete molding filling and easy adhesion between glass and mold for array microstructure glass elements with sharp edges and large aspect ratios such as compound eye arrays, V-grooves, rectangular grooves, pyramids, and Fresnel rings in traditional molding; unidirectional ultrasonic vibration cannot simultaneously change the adhesion and flow properties between glass elements and the upper and lower molds, resulting in different friction coefficients of the upper and lower contact surfaces, and leading to differences in the flow conditions of the upper and lower glass elements during molding, resulting in differences in stress, strain, and surface accuracy. Technical difficulties such as differences in stress, strain, and surface accuracy are brought about. The method has the technical advantages of improving the fluidity of glass materials in micro-scale mold grooves, improving the filling rate, surface accuracy, and molding uniformity of microstructures, and improving demolding difficulties and glass breakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The filling rate and stress distribution diagram of the microstructure array molding simulation with ultrasonic vibration applied to the lower mold only

[0029] Figure 2 It is a partial cross-sectional schematic diagram of the side view AA of the present invention

[0030] Figure 3 It is a side view schematic diagram of the present invention

[0031] Figure 4 This is a partial enlarged schematic diagram of part B of the present invention (and the structural mold assembly and glass)

[0032] Figure 5 It is a front view schematic diagram of the present invention

[0033] Figure 6 This is the principle diagram of the molding process of the present invention

[0034] In the figure: 1-molding device frame; 2-molding chamber; 3-high temperature resistant transparent glass plate; 4, 29-air cooling air inlet of the first and second ultrasonic vibration devices; 5, 22-first and second transducers; first and second 6, 28-assembly pre-tightening bolts; 7, 21-first and second ultrasonic vibration device condensation chambers; 8, 20-air cooling exhaust port of the first and second ultrasonic vibration device condensation chambers; 9, molding chamber support plate; 10, 30-first and second ultrasonic amplitude transformers; 11, 18-first and second insulation plates; 12, 16, 32, 34-first, third, fourth and second heating rods; 13-molding chamber air inlet; 14, 1 7-the first and second heat transfer platforms; 15-the thermocouple temperature control point of the lower mold; 19-pressure rod; 23-pressure sensor; 24-coupling; 25-servo electric cylinder; 26-servo motor; 27-connecting pin; 31-exhaust port of molding chamber; 33-the thermocouple temperature control point of the upper mold; 35-concave lower mold; 36-positioning inner sleeve; 37-limiting outer sleeve; 38-convex upper mold; 39-aspheric profile of the upper mold; 40-exhaust hole of mold; 41-glass; 42-compound eye array compound eye array sub-lens; 43-high temperature resistant transparent glass plate fastening bolt; 44-fixing sleeve; 45-molding cavity. DETAILED DESCRIPTION

[0035] Implementation method 1: Combination Figure 2 , Figure 3 , Figure 5The present embodiment of the present invention includes a molding device frame 1; a molding chamber 2; a high temperature resistant transparent glass plate 3; a first and a second ultrasonic vibration device condensation chamber air-cooling air inlet 4, 29; a first and a second transducer 5, 22; a first and a second assembly pre-tightening bolt 6, 28; a first and a second ultrasonic vibration device condensation chamber 7, 21; a first and a second ultrasonic vibration device condensation chamber air-cooling exhaust port 8, 21; a molding chamber support plate 9; a first and a second ultrasonic horn 10, 30; a first and a second insulation plate 11, 18; a first, a third, a fourth, a second heating rod 12, 16, 32, 33 connected to a heating source 4; molding chamber air inlet 13; first and second heat transfer platforms 14, 16; lower mold thermocouple temperature control point 15; pressure rod 19; pressure sensor 23; coupling 24; servo electric cylinder 25; servo motor 26; connecting pin 27; molding chamber exhaust port 31; upper mold thermocouple temperature control point 33; concave lower mold 35; positioning inner sleeve 36; outer sleeve 38; convex upper mold 38; upper mold aspheric profile 39; mold exhaust hole 40; glass 41; compound eye array compound eye array sub-lens 42; high temperature resistant transparent glass plate fixing bolt 43; fixing sleeve 44; molding cavity 45. The first and second transducers 5, 22 and the first and second ultrasonic horn 10, 30 are respectively assembled through the first and second pre-tightening fixing bolts 6, 28 to form an ultrasonic vibration device, and the number of the ultrasonic vibration devices is two, namely the first ultrasonic vibration device and the second ultrasonic vibration device, which together with the ultrasonic power supply form an ultrasonic vibration system. The molding chamber 2 is fixed on the molding chamber support plate 9 by 4 bolts. The molding chamber support plate 9, servo electric cylinder 25 and servo motor 26 are fixed on the molding device frame 1 by bolts. The molding chamber 2 is provided with molding chamber air inlet 13 and molding chamber exhaust port 31 on the left and right sides, which are used to transport nitrogen into the molding chamber to prevent mold oxidation under high temperature conditions. The first, third, fourth and second heating rods 12, 16, 32, 34, pressure rod 19 and ultrasonic amplitude transformer rod 10 connected to the heating source are all in the molding chamber to heat the glass and the mold and isolate the heat from transferring to the outside. A high temperature resistant transparent glass plate 3 is arranged on the front of the molding chamber. A sealing rubber sheet is used to achieve the sealing between the high temperature resistant transparent glass plate and the molding chamber, and the sealing is achieved by the set bolts 43, which is convenient for observation of the entire molding process.

[0036] Specific implementation method 2: Combination Figure 2 , Figure 4 To illustrate this embodiment, the concave lower mold 35 is fixed on the ultrasonic horn 10 and positioned by a fixed sleeve 44. The pressure rod 19 contacts the convex upper mold 38, and two ultrasonic vibration systems apply ultrasonic longitudinal vibration to the convex upper mold 38 and the concave lower mold 35 during molding. The output end of the electric cylinder is connected to the 310S stainless steel pressure rod through a weighing sensor, and the lower end of the pressure rod extends into the molding chamber to act on the upper mold. The servo motor 26 and the servo electric cylinder 25 are connected to the pressure sensor through a coupling 24.

[0037] Specific implementation method three: Combination Figure 2 To illustrate this embodiment, the sandwich ultrasonic first transducer 5 and the second transducer 22 are respectively composed of 5 pieces of 5mm thick piezoelectric ceramics, a front cover plate and a rear cover plate. The first ultrasonic horn 10 and the second ultrasonic horn 30 are respectively installed on the first transducer 5 and the second transducer 22 by threaded connection to form a first ultrasonic vibration device and a second ultrasonic vibration device. The ultrasonic vibration device is installed in the condensation chamber 7 of the first ultrasonic vibration device and in the condensation chamber 21 of the second ultrasonic vibration device. The condensation chamber 7 of the first ultrasonic vibration device is cooled by the air intake 4 of the first ultrasonic vibration device, and the air-cooled exhaust port 8 is used to cool the first ultrasonic vibration device; the condensation chamber 21 of the second ultrasonic vibration device is cooled by the air intake 29 of the second ultrasonic vibration device, and the air-cooled exhaust port 20 is used to cool the second ultrasonic vibration device.

[0038] Specific implementation method four: Combination Figure 2 , Figure 4 To explain this embodiment, the first ultrasonic vibration device is assembled and positioned with the uniform heat transfer platform 14, and an insulating plate 11 is provided between the uniform heat transfer platform 14 and the side wall of the molding chamber to prevent the high temperature of the uniform heat transfer platform from being transferred to the side wall of the molding chamber. The concave lower mold 35 is placed on the first ultrasonic vibration device, and a positioning sleeve 44 is provided between the uniform heat transfer platform and the ultrasonic amplitude rod and the outer sleeve. The lower mold thermocouple temperature control point 15 is installed on the top of the first ultrasonic vibration device in contact with the uniform heat transfer platform. The lower part of the second ultrasonic vibration device is connected to the pressure rod 19, and the pressure rod is assembled and positioned with the uniform heat transfer platform, and the pressure rod is in contact with the upper surface of the convex upper mold 38. The upper mold thermocouple temperature control point 33 is installed above the contact between the pressure rod and the upper surface of the convex upper mold.

[0039] Specific implementation method five: Combination Figure 2In this embodiment, the servo motor 26 controls the rotary motion through the motion control card, and then converts the motor rotation into the linear motion of the electric cylinder 25 screw through the ball screw pair, providing driving force and displacement for the terminal load. Finally, the real-time acquisition and feedback processing of the sensor pressure 23 signal and the encoder displacement signal are combined to achieve accurate closed-loop control of the output end driving force, displacement and speed. The first ultrasonic transducer 5 and the second ultrasonic transducer 22 are respectively connected to the ultrasonic power supply, and the first horn 10 and the second horn 30 are respectively connected to the first ultrasonic transducer 5 and the second ultrasonic transducer 22. First, the ultrasonic power supply generates a high-frequency alternating electrical signal, and then the high-frequency electrical signal is converted into mechanical vibration through the piezoelectric transducer. Finally, the mechanical vibration is amplified by the horn and transmitted to the upper mold, the lower mold and the glass blank respectively, thereby realizing ultrasonic vibration-assisted hot pressing of the glass element, and improving the filling rate and demolding performance of the microstructure glass optical element during the molding process. The heating temperature or cooling temperature of the mold and glass is detected in real time through the lower mold thermocouple temperature control point 15 and the upper mold thermocouple temperature control point 33, and the temperature signal is transmitted to the temperature controller to control the heating temperature of the heating source or the cooling system to heat up or cool down in real time, so as to control the temperature at the required temperature value.

[0040] Specific implementation method six: Combination Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 To illustrate this embodiment, a method for opposing ultrasonic vibration-assisted compression molding described in this embodiment includes the following steps.

[0041] Step 1: Remove the high-temperature transparent glass plate, and place the mold assembly loaded with glass on the upper surface of the ultrasonic horn that contacts the heat transfer platform and the outer sleeve, adjust the position of the pressure rod to just contact the upper mold surface, load the high-temperature transparent glass plate, and seal it.

[0042] Step 2: Start the servo motor to control the downward movement of the pressure rod, keep the bottom of the pressure rod just in contact with the top of the upper mold, start the heating source, heat the heat transfer platform through the heating rod, transfer the heat to the mold to heat it up, and raise the temperature to a certain temperature above the glass transition point. During the entire heating process, nitrogen is input through the molding air inlet to prevent oxidation of the mold, and the temperature is raised to a molding temperature above the glass transition point. Figure 6 (a).

[0043] Step 3: The molding process of the opposed ultrasonic vibration device adopts a three-stage ultrasonic vibration process, and the total molding time t is set z(90~120s), after the preset time t1 (20~30s) of the molding start, the first ultrasonic vibration device connected to the lower mold is started to apply ultrasonic longitudinal vibration to the lower mold, the vibration frequency range is 30~35KHz, the amplitude range is 8~10μm, and the time is t2 (30~40s), so as to increase the filling rate of the glass in the lower mold; then the second ultrasonic vibration device connected to the upper mold is started to apply ultrasonic longitudinal vibration to the upper mold, the vibration parameters are the same as those of the first ultrasonic vibration device, and the vibration application time is t3 (40~50s), so that the space between the upper and lower molds and the glass is completely filled, and at this time, the ultrasonic vibration time applied to the lower mold is (t2+t3)s; Figure 6 (b); In the annealing stage, the first ultrasonic vibration device and the second ultrasonic vibration device are turned off to reduce the temperature in the molding cavity, and the pressure holding and annealing treatment are performed under the same load, such as Figure 6 (c) Second cooling for demoulding pretreatment stage, lowering the temperature in the molding cavity again to the glass transition point temperature T g Below 50°C, the first ultrasonic vibration device and the second ultrasonic vibration device are turned on at the same time to perform ultrasonic vibration demoulding pretreatment. At this time, the vibration frequency is kept in the low-frequency vibration frequency range of 15 to 20 KHz, the amplitude range is 2 to 4 μm, and the time is t4 (20 to 30 s). Then, the first and second ultrasonic vibration devices are turned off to improve the demoulding performance between the optical element and the mold. Figure 6 (d); In the cooling stage, the temperature of the molding cavity is lowered again by the cold air provided by the chiller. After the cooling is completed, the mold is removed to obtain the desired molded optical element, such as Figure 6 (e).

[0044] The above is an explanation of a specific implementation example of the present invention. It should be pointed out that the present invention is not limited to the above-mentioned implementation mode. The ultrasonic vibration parameters and the molding process are not limited to the described structure and process parameters. The specific situation depends on the molding object and the glass parameter performance, which are all within the scope of protection of the present invention. However, those skilled in the art can make deformation or modification within the scope of the claims, which does not affect the essential content of the present invention.

Claims

1. A device for assisting compression molding with opposing ultrasonic vibrations, characterized in that: The invention comprises a first ultrasonic vibration device and a second ultrasonic vibration device which are arranged opposite to each other; the first ultrasonic vibration device is connected to a concave lower mold (35); the second ultrasonic vibration device is connected to a convex upper mold (38); a molding cavity (45) is formed between the concave lower mold (35) and the convex upper mold (38); the first ultrasonic vibration device and the second ultrasonic vibration device are both connected to a heating device; the second ultrasonic vibration device is connected to a lifting device via a pressure sensor (23); The opposed ultrasonic vibration assisted compression molding device further comprises a first ultrasonic vibration device outer cover and a second ultrasonic vibration device outer cover, the first ultrasonic vibration device outer cover is provided with a first ultrasonic vibration device condensation chamber (7), and the second ultrasonic vibration device outer cover is provided with a second ultrasonic vibration device condensation chamber (21); A first ultrasonic vibration device air-cooling air inlet (4) is installed on one side of the first ultrasonic vibration device condensation chamber (7), and a first ultrasonic vibration device air-cooling air outlet (8) is installed on the other side; A second ultrasonic vibration device air-cooling air inlet (29) is installed on one side of the second ultrasonic vibration device condensation chamber (21), and a second ultrasonic vibration device condensation chamber air-cooling air outlet (20) is installed on the other side; The opposed ultrasonic vibration assisted compression molding device also includes a compression molding chamber (2), wherein a concave lower mold (35) and a convex upper mold (38) are arranged in the compression molding chamber (2), a high temperature resistant transparent glass plate (3) is arranged on the front of the compression molding chamber (2), a sealing rubber sheet is used to achieve sealing between the high temperature resistant transparent glass plate (3) and the compression molding chamber (2), and sealing is achieved by means of a fixing bolt (43) so as to observe the compression molding process; The opposed ultrasonic vibration assisted compression molding device is also suitable for demoulding pretreatment: the demoulding pretreatment stage is performed by secondary cooling, the temperature in the molding cavity (45) is again reduced to 50±5°C below the glass transition temperature Tg, and the first ultrasonic vibration device and the second ultrasonic vibration device are simultaneously turned on to perform opposed ultrasonic vibration demoulding pretreatment, at which time the vibration frequency is maintained in the low-frequency vibration frequency range of 15 to 20 KHz, the amplitude range is 2 to 4 μm, and the time is t4, so as to improve the demoulding performance between the optical element and the mold, and then the first and second ultrasonic vibration devices are turned off, t4 = 20 to 30s.

2. The opposed ultrasonic vibration assisted molding device according to claim 1, characterized in that: The first ultrasonic vibration device comprises a first transducer (5), the first transducer (5) being connected to a first ultrasonic horn (10); the second ultrasonic vibration device comprises a second transducer (22), the second transducer (22) being connected to a second ultrasonic horn (30); the first transducer (5) and the second transducer (22) are both sandwich piezoelectric ceramic ultrasonic transducers.

3. The opposed ultrasonic vibration assisted molding device according to claim 2, characterized in that: The heating device comprises a first heating rod (12) and a second heating rod (34) connected to a first ultrasonic vibration device, and a third heating rod (16) and a fourth heating rod (32) connected to the second ultrasonic vibration device; the first heating rod (12) and the second heating rod (34) are connected to the first ultrasonic vibration device via a first uniform heat transfer platform (14); the third heating rod (16) and the fourth heating rod (32) are connected to the second ultrasonic vibration device via a second uniform heat transfer platform (17); the heating device is a heating rod, and the heating rod is connected to a heating source.

4. The opposed ultrasonic vibration assisted molding device according to claim 3, characterized in that: The first heating rod (12), the second heating rod (34), the third heating rod (16), the fourth heating rod (32), the concave lower mold (35) and the convex upper mold (38) are all installed in a molding chamber (2) formed by enclosing a high-temperature resistant transparent glass plate (3); the lower part of one side of the molding chamber (2) is connected to a molding chamber air inlet (13), and the upper part of the other side is connected to a molding chamber exhaust port (31).

5. The opposed ultrasonic vibration assisted molding device according to claim 3, characterized in that: An annular groove is formed on the first uniform heat transfer platform (14), and a positioning sleeve (44) is disposed in the annular groove. The positioning sleeve (44) is fixedly connected to the first ultrasonic horn (10) and the limiting outer sleeve (37). The limiting outer sleeve (37) is fixed outside the positioning inner sleeve (36), and mold exhaust holes (40) are formed on the positioning inner sleeve (36) and the limiting outer sleeve (37). The molding cavity (45) is located in the positioning inner sleeve (36). A lower mold thermocouple temperature control point (15) is installed between the top of the first ultrasonic horn (10) and the concave lower mold (35). A pressure rod (19) is connected to the bottom of the second ultrasonic horn (30), and an upper mold thermocouple temperature control point (33) is fixed between the pressure rod and the second uniform heat transfer platform (17).

6. The opposed ultrasonic vibration assisted molding device according to claim 3, characterized in that: A first insulation board (11) is installed between the high temperature resistant transparent glass plate (3) and the first uniform heat transfer platform (14); and a second insulation board (18) is installed between the high temperature resistant transparent glass plate (3) and the second uniform heat transfer platform (17).

7. The opposed ultrasonic vibration assisted molding device according to claim 1, characterized in that: The lifting device comprises a servo motor (26), the servo motor (26) is connected to a servo electric cylinder (25), and the servo electric cylinder (25) is connected to a pressure sensor (23) via a coupling (24).

8. A method for counter-acting ultrasonic vibration-assisted compression molding, characterized in that: Suitable for being performed in a facing ultrasonic vibration assisted compression molding device as described in any one of claims 1 to 7, the method comprises the following steps: Step 1: Install the glass in the molding cavity (45) formed between the concave lower mold (35) and the convex upper mold (38), and then heat the glass in a nitrogen atmosphere to a temperature above the glass transition point; Step 2: Start the lifting device connected to the convex mold (38), collect the downward pressure load for molding, and perform ultrasonic vibration during the molding process: set the total molding time tz, start the first ultrasonic vibration device connected to the concave lower mold (35) after the preset time t1 of the molding start, apply ultrasonic longitudinal vibration to the concave lower mold (35), the vibration frequency range is 30 to 35KHz, the amplitude range is 8 to 10μm, the time is t2, increase the filling rate of the glass of the concave lower mold (35), and then start A second ultrasonic vibration device connected to the convex upper mold (38) applies ultrasonic longitudinal vibration to the convex upper mold (38), and the vibration parameters are the same as those of the first ultrasonic vibration device. The applied vibration time is t3, so that the space between the convex upper mold (38), the concave lower mold (35) and the glass is completely filled. At this time, the ultrasonic vibration time applied to the concave lower mold (35) is (t2+t3)s, tz=90-120s, t1=20-30s, t2=30-40s, and t3=40-50s; Step 3: Annealing: During the annealing stage, the first ultrasonic vibration device and the second ultrasonic vibration device are turned off, the temperature inside the molding cavity (45) is lowered to a preset annealing temperature, and the pressure is maintained and the annealing process is performed under load; Step 4, demoulding pretreatment: the demoulding pretreatment stage is performed by cooling down for the second time, the temperature in the molding cavity (45) is lowered again to 50±5°C below the glass transition temperature Tg, and the first ultrasonic vibration device and the second ultrasonic vibration device are turned on at the same time to perform ultrasonic vibration demoulding pretreatment in the opposite direction, at which the vibration frequency is kept in the low-frequency vibration frequency range of 15 to 20 KHz, the amplitude range is 2 to 4 μm, and the time is t4, so as to improve the demoulding performance between the optical element and the mold, and then the first and second ultrasonic vibration devices are turned off, t4 = 20 to 30 s; Step 5, cooling: In the cooling stage, the temperature in the molding cavity (45) is lowered again by using the cold air provided by the chiller, and after cooling to room temperature, the mold is taken out to obtain the desired molded optical element; Wherein, the first ultrasonic vibration device is provided with a first ultrasonic vibration device outer cover, the second ultrasonic vibration device is provided with a second ultrasonic vibration device outer cover, the first ultrasonic vibration device outer cover is provided with a first ultrasonic vibration device condensation chamber (7), and the second ultrasonic vibration device outer cover is provided with a second ultrasonic vibration device condensation chamber (21); the first ultrasonic vibration device condensation chamber (7) is provided with an air-cooled air inlet (4) for the first ultrasonic vibration device on one side, and an air-cooled air outlet (8) for the first ultrasonic vibration device condensation chamber on the other side; the second ultrasonic vibration device condensation chamber (21) is provided with an air-cooled air inlet (29) for the second ultrasonic vibration device on one side, and an air-cooled air outlet (20) for the second ultrasonic vibration device condensation chamber on the other side; The opposed ultrasonic vibration assisted compression molding device also includes a compression molding chamber (2), in which a concave lower mold (35) and a convex upper mold (38) are arranged, and a high temperature resistant transparent glass plate (3) is arranged on the front of the compression molding chamber (2). A sealing rubber sheet is used to achieve sealing between the high temperature resistant transparent glass plate and the compression molding chamber, and sealing is achieved by tightening bolts (43) to facilitate observation of the compression molding process.

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