CN111960651A - Opposite ultrasonic vibration assisted die forming device and method - Google Patents
Opposite ultrasonic vibration assisted die forming device and method Download PDFInfo
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- CN111960651A CN111960651A CN202010941481.1A CN202010941481A CN111960651A CN 111960651 A CN111960651 A CN 111960651A CN 202010941481 A CN202010941481 A CN 202010941481A CN 111960651 A CN111960651 A CN 111960651A
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- 238000000465 moulding Methods 0.000 claims abstract description 47
- 238000003825 pressing Methods 0.000 claims abstract description 43
- 238000011049 filling Methods 0.000 claims abstract description 23
- 238000007723 die pressing method Methods 0.000 claims abstract description 22
- 230000008569 process Effects 0.000 claims abstract description 13
- 238000001816 cooling Methods 0.000 claims description 31
- 238000009833 condensation Methods 0.000 claims description 24
- 230000005494 condensation Effects 0.000 claims description 23
- 230000003287 optical effect Effects 0.000 claims description 20
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- 238000000137 annealing Methods 0.000 claims description 10
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- 238000009413 insulation Methods 0.000 claims description 6
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
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- 238000010894 electron beam technology Methods 0.000 description 1
- 229920006158 high molecular weight polymer Polymers 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
- C03B11/12—Cooling, heating, or insulating the plunger, the mould, or the glass-pressing machine; cooling or heating of the glass in the mould
- C03B11/122—Heating
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
- C03B11/06—Construction of plunger or mould
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
- C03B11/06—Construction of plunger or mould
- C03B11/08—Construction of plunger or mould for making solid articles, e.g. lenses
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Abstract
The invention discloses a device and a method for assisting in die pressing and forming by opposite ultrasonic vibration, which consists of an opposite ultrasonic vibration system, a servo loading system and a heating system for heating an electric heating rod and transferring heat by a vapor chamber, and can realize the simultaneous application of ultrasonic longitudinal vibration, accurate servo loading and real-time adjustment and control of die pressing temperature on an upper die and a lower die in the die pressing process. Compared with the traditional mould pressing and one-way ultrasonic vibration mould pressing methods, the problems that the mould pressing and filling of the traditional mould pressing are incomplete and the glass is easy to adhere to the mould aiming at array microstructure glass elements such as compound eye arrays, V grooves, rectangular grooves, pyramids, Fresnel rings and the like which have sharp edges and large depth-diameter ratio are effectively solved; the ultrasonic vibration molding pressure which only applies ultrasonic vibration to the upper mold cannot change the adhesion and the flow performance between the glass element and the lower mold, so that the friction coefficients of upper and lower contact molded surfaces are different, the flow conditions of the upper part and the lower part of the glass element are different during molding, and the technical problems of difference of stress, strain, surface accuracy and the like are caused.
Description
Technical Field
The invention relates to the field of mold pressing forming of microstructure glass optical elements, in particular to a device and a method for mold pressing forming assisted by opposite ultrasonic vibration, which are used for improving mold pressing filling rate and demolding performance of microstructure glass optical elements.
Background
In recent years, the optical industry has increasingly demanded the surface of glass microstructures such as microlenses, microgrooves, microcones, and microprisms. The glass optical element with the micro-surface structure, particularly the micro-structure compound eye array lens, has an important effect on improving the imaging quality of an optical system, can provide various optical functions and better imaging quality by virtue of special geometric characteristics of the glass optical element, becomes a core device in the fields of smart phones, digital cameras, space optical communication, infrared detection, medical equipment, intelligent guidance systems and the like, and can realize imaging, reflection and diffraction functions of high definition, high resolution, high uniformity and shaping and beam expansion.
The mold pressing forming technology for the microstructure glass optical element has the advantages of high repetition precision, no pollution, net forming, low cost, suitability for mass production and the like, and is considered to be one of the most revolutionary optical manufacturing technologies in the world. Compared with the traditional lens manufacturing methods such as fast tool servo single-point diamond turning, femtosecond laser beams, electron beams, plasma beams, LIGA technology and the like, the method has the advantages of high production efficiency, diversified processing materials, good processing consistency, good process stability and the like. However, for array type microstructure glass elements with sharp edges and large depth-diameter ratio, such as compound eye arrays, V-shaped grooves, rectangular grooves, pyramids, Fresnel rings and the like, the existing compression molding method has the defects that the flow and deformation of glass materials in the grooves of the micro-scale mold are blocked in the hot pressing process, so that the mold filling rate of the formed glass microstructure is insufficient, and the geometric precision of products is reduced; the contact interface of the glass and the mold is easy to bond, so that the mold-filling part of the glass microstructure is difficult to demould after molding, and the glass is broken.
The ultrasonic vibration assisted die pressing is characterized in that an ultrasonic vibration system is introduced to apply longitudinal ultrasonic longitudinal vibration to a die pressing system on the basis of the traditional die pressing principle, so that the filling rate and the demolding performance in the die pressing process can be improved, and the technical problem existing in the traditional die pressing is solved.
In the domestic disclosure and data, the utility model of the university of Hunan (patent ZL201420846015.5) provides an ultrasonic vibration precision compression molding device of an optical element with a complex microstructure, which comprises a cylinder, a slide block, a guide rail, a connecting rod, an ultrasonic generator, an energy converter, an amplitude transformer, a heat insulation plate and a heating plate. The application of the device reduces the adhesion and damage of the glass element to the surface of the die, and realizes the precise die forming of the optical element with the mixed microstructure. However, the device only applies longitudinal ultrasonic vibration to the upper die, so that the effect of improving the mold pressing filling rate and the mold release performance is limited, and only vibrates on one side of the upper die, which is helpful for improving the mold release adhesion condition between the glass element and the upper die but cannot improve the mold release adhesion condition between the glass element and the lower die; the vibration only on the upper die side changes the friction coefficient and the flow condition between the glass element and the upper die, but the friction coefficient and the flow condition between the glass element and the lower die cannot be changed, so that the friction coefficients of upper and lower contact profiles are different, the flow conditions of the upper part and the lower part of the glass element are different during molding, and the difference of stress, strain and surface accuracy is caused. As shown in fig. 1, after the unidirectional ultrasonic vibration is applied to the upper mold, the filling edge line of the upper mold fly-eye lens and the mold contour line are not overlapped, that is, the filling is not completely performed, and the filling edge line of the lower mold concave lens and the mold contour line are not overlapped, and the deviation amount of the filling edge line and the mold contour line is larger than that of the upper mold, and meanwhile, the stress at the contact position of the lower mold contour line and the filling edge line of the concave lens is larger than that of the upper mold contour line and that of the filling edge line of the sub fly-eye lens.
In foreign publications, there are no reports on an apparatus and a method for assisting molding by ultrasonic vibration, but there are patents related to the application of ultrasonic vibration to injection molding of resin materials. European patent (EP1645381a8) registered by japan letter corporation provides an apparatus and a method for melt-molding a resin material by applying ultrasonic vibration to the resin material, wherein the molding material is fed into a mold located at one end of a cylinder, and the material in the cylinder is melted and kneaded, and the molding material is vibrated in one direction on the right side so as to intersect with the flow direction of the resin material. U.S. patent registered to Toshihiro Furusawa et al (US5017311A) of japan provides a method for improving the flowability of a high molecular weight polymer using ultrasonic vibration, the injection molding apparatus having a fixed mold and a movable mold; one side of the movable die is provided with a cavity, and the other side of the movable die is connected with an ultrasonic vibration feeding device. The methods provided by the two patents are only limited to injection molding of resin materials, because glass materials can be softened only at a higher temperature, the glass materials are poor in flowability and have strong adhesion, the molding temperature of the resin materials is low, the glass is molten during injection molding, the purpose of applying ultrasonic vibration is mainly used for demolding, but the purpose of applying ultrasonic vibration by using ultrasonic vibration to assist mold pressing is to improve the filling rate and the demolding performance, so that the two patents are different in molding principle and mechanism, and meanwhile, the two patents are both unidirectional ultrasonic vibration, and the technical defect that the demolding adhesion condition of a lower mold is only changed is the same.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a device and a method for auxiliary die pressing and forming by opposite ultrasonic vibration, and can solve the problems that when an optical element with a complex microstructure is subjected to unidirectional ultrasonic die pressing and forming: 1) demoulding of the upper mould and the lower mould is difficult, 2) the flow conditions of the upper part and the lower part of the glass element are inconsistent, which causes the problems of uneven stress and strain, uneven surface shape precision and the like, improves the fluidity of the glass material in the groove of the micro-scale mould, improves the filling rate and the surface shape precision of the microstructure, and solves the problems of difficult demoulding, glass breakage and the like.
In order to achieve the purpose, the technical scheme of the invention is as follows:
an opposite ultrasonic vibration auxiliary die forming device comprises a first ultrasonic vibration device and a second ultrasonic vibration device which are oppositely arranged; the first ultrasonic vibration device is connected with a concave lower die 35; the second ultrasonic vibration device is connected with the convex upper die 38, and a die pressing cavity 45 is formed between the concave lower die 35 and the convex upper die 38; the first ultrasonic vibration device and the first ultrasonic vibration device are both connected with a heating device; the second ultrasonic vibration device is connected with a lifting device through a pressure sensor 23.
In a further improvement, the first ultrasonic vibration device comprises a first transducer 5, and a first ultrasonic amplitude transformer 10 is connected with the first transducer 5; the second ultrasonic vibration device comprises a second transducer 10, and a second ultrasonic amplitude transformer 30 is connected with the second transducer 10; the first transducer 5 and the second transducer 10 are both sandwich type piezoelectric ceramic ultrasonic transducers.
In a further refinement, the heating means comprise a first heating rod 12 and a second heating rod 34 connected to the first ultrasonic vibration means and a third heating rod 16 and a fourth heating rod 32 connected to the second ultrasonic vibration means; the first heating rod 12 and the second heating rod 34 are connected with the first ultrasonic vibration device through the first soaking heat transfer table 14; the third heating rod 16 and the fourth heating rod 32 are connected with a second ultrasonic vibration device through a second uniform heat transfer table 17; the heating device is a heating rod, and the heating rod is connected with a heating source.
In 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 die 35 and the convex upper die 38 are all arranged in a die pressing chamber 2 formed by enclosing the high-temperature resistant transparent glass plate 3; the lower part of one side of the molding chamber 2 is communicated with a molding chamber air inlet 13, and the upper part of the other side is communicated with a molding chamber air outlet 31.
In a further improvement, a first ultrasonic vibration device condensation cavity 7 is arranged on the first ultrasonic vibration device housing, and a second ultrasonic vibration device condensation cavity 21 is arranged on the second ultrasonic vibration device housing; a first ultrasonic vibration device air-cooling inlet 4 is arranged on one side of a first ultrasonic vibration device condensation cavity 7, and a first ultrasonic vibration device condensation cavity air-cooling exhaust port 8 is arranged on the other side of the first ultrasonic vibration device condensation cavity; and a second ultrasonic vibration device air cooling air inlet 29 is arranged on one side of the second ultrasonic vibration device condensation cavity 21, and a second ultrasonic vibration device condensation cavity air cooling air outlet 20 is arranged on the other side of the second ultrasonic vibration device condensation cavity.
In a further improvement, an annular groove is formed in the first soaking heat transfer table 14, a positioning sleeve 44 is arranged in the annular groove, the positioning sleeve 44 is fixedly connected with the first ultrasonic amplitude transformer 10 and the limiting outer sleeve 37, the limiting outer sleeve 37 is fixed outside the inner sleeve 36, and a mold exhaust hole 40 is formed in each of the positioning inner sleeve 36 and the outer sleeve 37; mold cavity 45 is within inner sleeve 36; a lower die thermocouple temperature control point 15 is arranged between the top of the first ultrasonic amplitude transformer 10 and the concave lower die 35; the bottom of the second ultrasonic amplitude transformer 30 is connected with a pressure rod 19, and an upper die thermocouple temperature control point 33 is fixed between the pressure rod and the second soaking heat transfer table 17.
In a further improvement, a first heat insulation plate 11 is arranged between the high-temperature resistant transparent glass plate 3 and a first soaking heat platform 14; a second heat insulation plate 18 is arranged between the high-temperature resistant transparent glass plate 3 and the second soaking heat transfer platform 17.
In a further improvement, the lifting device comprises a servo motor 26, a servo electric cylinder 25 is connected to the servo motor 26, and the servo electric cylinder 25 is connected with the pressure sensor 23 through a pressure sensor 24.
A method of counter-ultrasonic vibration assisted die forming, the method comprising the steps of:
step one, mounting glass between a lower die and an upper die to form a die pressing cavity 45; then heating the glass in a nitrogen atmosphere, and raising the temperature to be higher than the glass transition point temperature;
step two, start the lifting gear that mould 38 connects on the convex surface to gather and push down the load and carry out the mould pressing, in the mould pressing process, carry out ultrasonic vibration: setting the total time t of moldingzThe molding start preset time t1A first ultrasonic vibration device connected with the lower die is started to apply ultrasonic longitudinal vibration to the lower die, the vibration frequency range is 30-35 KHz, the amplitude range is 8-10 mu m, and the time is t2Increasing the filling rate of the glass of the lower die; then a second ultrasonic vibration device connected with the upper die is started to apply ultrasonic longitudinal vibration to the upper die, the vibration parameters are the same as those of the first ultrasonic vibration device, and the vibration application time is t3Completely filling the space between the upper and lower molds and the glass, wherein the time for applying ultrasonic vibration to the lower mold is (t)2+t3)s；tz＝90～120s，t1＝20～30s，t2＝30～40s，t3＝40～50s；
Step three, annealing: in the annealing stage, the first ultrasonic vibration device and the second ultrasonic vibration device are closed, the temperature in the die pressing cavity is reduced to a preset annealing temperature, and pressure maintaining and annealing treatment are carried out under the condition of keeping the load;
step four, demolding pretreatment: performing secondary cooling for demolding, and reducing the temperature in the mold pressing cavity to the glass transition point temperature TgStarting a first ultrasonic vibration device and a second ultrasonic vibration device at the same time at the temperature of 50 +/-5 ℃ below zero to perform opposite ultrasonic vibration demoulding pretreatment, and keeping the vibration frequency within the low-frequency vibration frequency range of 15-20 KHz, the amplitude range of 2-4 mu m and the time of t4The demolding performance between the optical element and the mold is improved, and then the first ultrasonic vibration device and the second ultrasonic vibration device are closed; t is t4＝20～30s；
Step five, cooling: and in the cooling stage, the temperature of the mould pressing cavity is reduced again by using cold air provided by a water chiller to be cooled, and the mould is taken out after the mould is cooled to the room temperature to obtain the required mould pressing optical element.
The servo motor controls rotary motion through the motion control card, the rotation of the motor is converted into linear motion of the electric cylinder screw through the ball screw pair, driving force and displacement are provided for a terminal load, and finally accurate closed-loop control of the driving force, the displacement and the speed of an output end is achieved by combining real-time acquisition and feedback processing of a pressure signal of the sensor and a displacement signal of the encoder.
The ultrasonic transducer is connected with an ultrasonic power supply, the amplitude transformer is connected with the ultrasonic transducer, firstly, the ultrasonic power supply generates a high-frequency alternating electrical signal, then the high-frequency electrical signal is converted into mechanical vibration through the piezoelectric transducer, and finally, the mechanical vibration is amplified through the amplitude transformer and is respectively transmitted to the upper die, the lower die and the glass blank, so that the ultrasonic vibration-assisted hot press molding of the glass element is realized.
The heating temperature or the cooling temperature of the mold and the glass realize real-time temperature detection through a thermocouple temperature control point, and the temperature signal is transmitted to a temperature controller to control the heating temperature or the cooling system of the heating source to carry out real-time temperature rise or cooling, so that the temperature is controlled at a required temperature value.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a device and a method for assisting in die pressing and forming by opposite ultrasonic vibration. Compared with the traditional precision mould pressing and the existing one-way ultrasonic vibration mould pressing method, the mould pressing process method which adopts the opposite ultrasonic vibration auxiliary mould pressing device and the sectional type ultrasonic vibration effectively solves the problems that the mould pressing of the traditional mould pressing is incomplete in mould pressing and the glass is easy to adhere to the mould, and the traditional mould pressing aims at array type micro-structure glass elements with sharp edges and angles, large depth-diameter ratio and the like such as a compound eye array, a V groove, a rectangular groove, a pyramid, a Fresnel ring and the like; the unidirectional ultrasonic vibration cannot simultaneously change the adhesion and the flow performance between the glass element and the upper and lower dies, so that the friction coefficients of upper and lower contact molded surfaces are different, the flow conditions of the upper part and the lower part of the glass element are different during molding, the difference of stress, strain and surface accuracy is caused, and the like, and the technical problems are solved, and the method has the technical advantages of improving the fluidity of the glass material in a micro-scale die groove, improving the mold filling rate, the surface accuracy and the molding uniformity of a microstructure, improving the demolding difficulty, glass breakage and the like.
Drawings
FIG. 1 is a graph of simulated filling rate and stress distribution of microstructure array molding by applying ultrasonic vibration only to a lower mold
FIG. 2 is a schematic view of the invention in partial section from the side view A-A
FIG. 3 is a side view of the present invention
FIG. 4 is a partially enlarged view of the portion B of the present invention (with the structural mold assembly and glass)
FIG. 5 is a front view of the present invention
FIG. 6 is a schematic diagram of the press molding of the present invention
In the figure: 1-a die forming device frame; 2-a molding chamber; 3-high temperature resistant transparent glass plate; 4. 29-air cooling air inlets of the first ultrasonic vibration device and the second ultrasonic vibration device; 5. 22-first and second transducers; first, second 6, 28-assembling pre-tightening bolts; 7. 21-condensation chambers of the first and second ultrasonic vibration devices; 8. 20-air cooling exhaust ports of condensation chambers of the first ultrasonic vibration device and the second ultrasonic vibration device; 9. a mold press chamber support plate; 10. 30-a first ultrasonic horn and a second ultrasonic horn; 11. 18-primary and secondary insulation panels; 12. 16, 32, 34-first, third, fourth, second heating rod; 13-die pressing chamber air inlet; 14. 17-first and second soaking heat transfer tables; 15-thermocouple temperature control point of lower die; 19-a compression bar; 23-a pressure sensor; 24-a coupling; 25-servo electric cylinder; 26-a servo motor; 27-a connecting pin; 31-mold chamber vent; 33-temperature control point of upper die thermocouple; 35-concave lower mold; 36-positioning the inner sleeve; 37-a spacing outer sleeve; 38-convex upper mold; 39-upper mold aspheric profile; 40-mold vent holes; 41-glass; 42-fly-eye array sub-lens; 43-high temperature resistant transparent glass plate fastening bolt; 44-a fixed sleeve; 45-mould pressing chamber.
Detailed Description
The first implementation mode comprises the following steps: the present embodiment is described with reference to fig. 2, 3, and 5, and the present invention includes a frame 1 of a press molding apparatus; a molding pressure chamber 2; a high temperature resistant transparent glass plate 3; the first and second ultrasonic vibration devices are respectively provided with a condensation cavity air- cooling air inlet 4 and 29; the first and second transducers 5, 22; the first and second assembling pre-tightening bolts 6 and 28; condensation chambers 7, 21 of the first and second ultrasonic vibration devices; the first and second ultrasonic vibration devices are respectively provided with a condensation cavity air cooling exhaust port 8, 21; a molding chamber support plate 9; first and second ultrasonic horns 10, 30; first and second insulating plates 11, 18; the first, third, fourth and second heating rods 12, 16, 32 and 34 are connected with a heating source; a molding chamber inlet 13; first and second thermally homogeneous conductive stages 14, 16; a lower die thermocouple temperature control point 15; a pressure lever 19; a pressure sensor 23; a coupling 24; a servo electric cylinder 25; a servo motor 26; a connecting pin 27; a molding chamber vent 31; upper mold thermocouple temperature control point 33; a concave lower mold 35; positioning the inner sleeve 36; an outer sleeve 38; a convex upper die 38; upper mold aspheric profile 39; a mold vent 40; a glass 41; fly-eye array sub-lens 42; a high temperature resistant transparent glass plate fastening bolt 43; a fixed sleeve 44; and a die pressing chamber 45. The first and second transducers 5 and 22 and the first and second ultrasonic horns 10 and 30 are assembled through the first and second pre-tightening fixing bolts 6 and 28 to form ultrasonic vibration devices, and the number of the ultrasonic vibration devices is 2, namely the first ultrasonic vibration device and the second ultrasonic vibration device form an ultrasonic vibration system together with an ultrasonic power supply. The molding chamber 2 is fixedly connected with a molding chamber supporting plate 9 through 4 bolts, and the molding chamber supporting plate 9 and the servo electric cylinder 25 are arranged on the molding chamber supporting plate 9; the servo motors 26 are fixed on the molding forming device rack 1 through bolts, and the left side and the right side of the molding chamber 2 are provided with a molding chamber air inlet 13 and a molding chamber air outlet 31 for conveying nitrogen into the molding chamber to prevent the mold from being oxidized under high temperature conditions. The method comprises the following steps of; the first, third, fourth and second heating rods 12, 16, 32, 34, the pressure rod 19 and the ultrasonic amplitude transformer 10 which are connected with the heating source are all arranged in the mould pressing chamber to heat the glass and the mould and isolate heat from transferring heat outwards, the front surface of the mould pressing chamber is provided with a high-temperature resistant transparent glass plate 3, sealing between the high-temperature resistant transparent glass plate and the mould pressing chamber is realized by adopting a sealing rubber sheet, sealing is realized by a fastening bolt 43, and observation of the whole mould pressing process is facilitated.
The second embodiment is as follows: referring to fig. 2 and 4, the concave lower die 35 is fixed to the ultrasonic horn 10 and positioned by the fixing sleeve 44. The compression bar 19 is in contact with the upper convex die 38, and two ultrasonic vibration systems respectively apply ultrasonic longitudinal vibration to the upper convex die 38 and the lower concave die 35 during die pressing. The output end of the electric cylinder is connected with a 310S stainless steel pressure rod through a weighing sensor, and the lower end of the pressure rod extends into the mould pressing chamber to act on the upper mould. The servo motor 26 and the servo electric cylinder 25 are connected with the pressure sensor through a coupler 24.
The third concrete implementation mode: the embodiment is described with reference to fig. 2, the sandwich type ultrasonic first transducer 5 and the sandwich type ultrasonic second transducer 22 are respectively composed of 5 piezoelectric ceramics with thickness of 5mm, 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 through threaded connection to form a first ultrasonic vibration device and a second ultrasonic vibration device, the ultrasonic vibration devices are installed in a first ultrasonic vibration device condensation cavity 7 and a second ultrasonic vibration device condensation cavity 21, the first ultrasonic vibration device condensation cavity 7 is used for air-cooling the air inlet 4 through the first ultrasonic vibration device, and the air-cooling exhaust port 8 is used for cooling the first ultrasonic vibration device; the second ultrasonic vibration device condensation cavity 21 cools the air inlet 29 through the second ultrasonic vibration device air cooling, and the air cooling exhaust port 20 cools the second ultrasonic vibration device.
The fourth concrete implementation mode: in the embodiment, the first ultrasonic vibration device is assembled and positioned with the soaking heat transfer table 14, and the heat insulation plate 11 is arranged between the soaking heat transfer table 14 and the sidewall of the molding chamber to prevent the high temperature of the soaking heat transfer table from being transferred to the sidewall of the molding chamber. The concave lower die 35 is arranged on the first ultrasonic vibration device, a positioning sleeve 44 is arranged between the soaking heat transfer table and the ultrasonic amplitude transformer and the outer sleeve, and the lower die thermocouple temperature control point 15 is arranged at the top of the first ultrasonic vibration device which is in contact with the soaking heat transfer table. The lower part of the second ultrasonic vibration device is connected with a pressure lever 19, the pressure lever is assembled and positioned with the soaking heat transfer table, the pressure lever is in contact with the upper surface of the convex upper die 38, and the upper die thermocouple temperature control point 33 is arranged above the contact position of the pressure lever and the upper surface of the convex upper die.
The fifth concrete implementation mode: referring to fig. 2, in the 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, so as to provide the driving force and displacement for the terminal load, and finally, the precise closed-loop control of the driving force, displacement and speed at the output end is realized by combining the real-time acquisition and feedback processing of the sensor pressure 23 signal and the encoder displacement signal. The first ultrasonic transducer 5 and the second ultrasonic transducer 22 are respectively connected with an ultrasonic power supply, the first amplitude transformer 10 and the second amplitude transformer 30 are respectively connected with the first ultrasonic transducer 5 and the second ultrasonic transducer 22, firstly, the ultrasonic power supply generates a high-frequency alternating electric signal, then the high-frequency electric signal is converted into mechanical vibration through the piezoelectric transducers, and finally, the mechanical vibration is amplified through the amplitude transformers and is respectively transmitted to the upper die, the lower die and the glass blank, so that the ultrasonic vibration-assisted hot press molding of the glass element is realized, and the filling rate and the demoulding performance of the microstructure glass optical element in the press molding process are improved. The heating temperature or the cooling temperature of the mold and the 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 a heating temperature or a cooling system of a temperature controller for controlling a heating source to heat or cool in real time, so that the temperature is controlled at a required temperature value.
The sixth specific implementation mode: the present embodiment is described with reference to fig. 2, 3, 4, 5, and 6, and the method for assisting press molding with ultrasonic vibration described in the present embodiment includes the following steps.
The method comprises the following steps: and (3) unloading the high-temperature transparent glass plate, placing the mold assembly loaded with the glass on the upper surface of the ultrasonic amplitude transformer in contact fit with the heat transfer platform and the outer sleeve, adjusting the position of the pressure rod to just contact with the surface of the upper mold, loading the high-temperature transparent glass plate, and sealing.
Step two: starting servo motor, control depression bar downstream keeps depression bar bottom just with last mould top contact, starts the heating source, heats to heat transfer platform through the heating rod, and heat transfer heats up to the mould, and the temperature risees to the above uniform temperature of glass transition point temperature, and whole heating process passes through mould pressing air inlet input nitrogen gas prevents the mould oxidation, and the mould pressing temperature that rises to the above glass transition point temperature with the temperature, like figure 6 (a).
Step three: the mould pressing process of the opposite ultrasonic vibration device adopts a three-section type ultrasonic vibration process, and the total mould pressing time t is setz(90-120 s), and the preset time t is preset when the mould pressing starts1After (20-30 s), starting a first ultrasonic vibration device connected with the lower die to apply ultrasonic longitudinal vibration to the lower die, wherein the vibration frequency range is 30-35 KHz, the amplitude range is 8-10 mu m, and the time is t2(30-40 s), increasing the filling rate of the lower die glass; then a second ultrasonic vibration device connected with the upper die is started to apply ultrasonic longitudinal vibration to the upper die, the vibration parameters are the same as those of the first ultrasonic vibration device, and the vibration application time is t3(40-50 s), completely filling the space between the upper and lower dies and the glass, wherein the time for applying ultrasonic vibration to the lower die is (t)2+t3) s; as shown in fig. 6 (b); an annealing stage, in which the first ultrasonic vibration device and the second ultrasonic vibration device are turned offAn ultrasonic vibration device for reducing the temperature in the die pressing cavity and performing pressure maintaining and annealing treatment under the same load, as shown in fig. 6 (c); performing secondary cooling for demolding, and reducing the temperature in the mold pressing cavity to the glass transition point temperature TgStarting a first ultrasonic vibration device and a second ultrasonic vibration device at the same time to carry out opposite ultrasonic vibration demoulding pretreatment at the temperature of about 50 ℃, and keeping the vibration frequency within the low-frequency vibration frequency range of 15-20 KHz, the amplitude range of 2-4 mu m and the time of t4(20-30 s), then closing the first ultrasonic vibration device and the second ultrasonic vibration device so as to improve the demolding performance between the optical element and the mold, as shown in fig. 6 (d); and in the cooling stage, the temperature of the mould pressing cavity is reduced again by using cold air provided by a water chiller to cool, and after cooling is finished, the mould is taken out to obtain the required mould pressing optical element, as shown in fig. 6 (e).
The above is for the purpose of illustrating the specific embodiments of the present invention, and it should be noted that the present invention is not limited to the above embodiments, and the ultrasonic vibration parameters and the molding process are not limited to the described structure and process parameters, and the specific conditions thereof are determined by the molding objects and the glass parameter performance, which are within the protection scope of the present invention, but those skilled in the art can make modifications or changes within the scope of the claims, which do not affect the essence of the present invention.
Claims (9)
1. The opposite ultrasonic vibration assisted die forming device is characterized by comprising a first ultrasonic vibration device and a second ultrasonic vibration device which are oppositely arranged; the first ultrasonic vibration device is connected with a concave lower die (35); the second ultrasonic vibration device is connected with a convex upper die (38), and a die pressing cavity (45) is formed between the concave lower die (35) and the convex upper die (38); the first ultrasonic vibration device and the first ultrasonic vibration device are both connected with a heating device; the second ultrasonic vibration device is connected with a lifting device through a pressure sensor (23).
2. A counter ultrasonic vibration assisted die forming apparatus as claimed in claim 1, wherein the first ultrasonic vibration means 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 (10), and a second ultrasonic amplitude transformer (30) is connected to the second transducer (10); the first transducer (5) and the second transducer (10) are both sandwich type piezoelectric ceramic ultrasonic transducers.
3. A counter ultrasonic vibration assisted press-molding apparatus as claimed in claim 2, wherein said heating means comprises a first heating rod (12) and a second heating rod (34) connected to the first ultrasonic vibration means and a third heating rod (16) and a fourth heating rod (32) connected to the second ultrasonic vibration means; the first heating rod (12) and the second heating rod (34) are connected with the first ultrasonic vibration device through the first heat-homogenizing heat-transferring table (14); the third heating rod (16) and the fourth heating rod (32) are connected with the second ultrasonic vibration device through a second heat-homogenizing heat-transferring table (17); the heating device is a heating rod, and the heating rod is connected with a heating source.
4. An opposite ultrasonic vibration assisted press forming device as claimed in claim 3, wherein the first heating rod (12), the second heating rod (34), the third heating rod (16), the fourth heating rod (32), the concave lower die (35) and the convex upper die (38) are all installed in a press chamber (2) formed by enclosing the high temperature resistant transparent glass plate (3); the lower part of one side of the molding chamber (2) is communicated with a molding chamber air inlet (13), and the upper part of the other side is communicated with a molding chamber air outlet (31).
5. A counter ultrasonic vibration assisted press-molding apparatus as claimed in claim 1, wherein said first ultrasonic vibration device housing is provided with a first ultrasonic vibration device condensation chamber (7), and said second ultrasonic vibration device housing is provided with a second ultrasonic vibration device condensation chamber (21); a first ultrasonic vibration device air-cooling air inlet (4) is arranged on one side of a first ultrasonic vibration device condensation cavity (7), and a first ultrasonic vibration device condensation cavity air-cooling air outlet (8) is arranged on the other side of the first ultrasonic vibration device condensation cavity; and one side of the second ultrasonic vibration device condensation cavity (21) is provided with a second ultrasonic vibration device air-cooling air inlet (29), and the other side is provided with a second ultrasonic vibration device condensation cavity air-cooling air outlet (20).
6. The counter ultrasonic vibration-assisted die forming device as claimed in claim 3, wherein the first soaking station (14) is provided with an annular groove, a positioning sleeve (44) is arranged in the annular groove, the positioning sleeve (44) is fixedly connected with the first ultrasonic amplitude transformer (10) and the limiting outer sleeve (37), the limiting outer sleeve (37) is fixedly arranged outside the inner sleeve (36), and the die exhaust holes (40) are formed in the positioning inner sleeve (36) and the outer sleeve (37); the mould pressing cavity (45) is positioned in the inner sleeve (36); a lower die thermocouple temperature control point (15) is arranged between the top of the first ultrasonic amplitude transformer (10) and the concave lower die (35); the bottom of the second ultrasonic amplitude transformer (30) is connected with a pressure lever (19), and an upper die thermocouple temperature control point (33) is fixed between the pressure lever and the second heat-homogenizing and heat-transferring table (17).
7. An opposite ultrasonic vibration assisted press-forming device as defined in claim 3, wherein a first heat insulating plate (11) is installed between the high temperature resistant transparent glass plate (3) and the first soaking heat stage (14); a second heat insulation plate (18) is arranged between the high-temperature resistant transparent glass plate (3) and the second heat homogenizing and transmitting table (17).
8. An opposite ultrasonic vibration assisted die forming device as claimed in claim 1, wherein the elevating means comprises a servo motor (26), a servo electric cylinder (25) is connected to the servo motor (26), and the servo electric cylinder (25) is connected to the pressure sensor (23) through a pressure sensor (24).
9. A counter ultrasonic vibration assisted die forming method is characterized by comprising the following steps:
step one, mounting glass between a lower die and an upper die to form a die pressing cavity (45); then heating the glass in a nitrogen atmosphere, and raising the temperature to be higher than the glass transition point temperature;
step two, start the elevating gear that mould (38) are connected on the convex surface to gather and push down the load and carry out the mould pressing, in the mould pressing process, carry out ultrasonic vibration: setting the total time t of moldingzThe molding start preset time t1After startThe first ultrasonic vibration device connected with the lower die applies ultrasonic longitudinal vibration to the lower die, the vibration frequency range is 30-35 KHz, the amplitude range is 8-10 mu m, and the time is t2Increasing the filling rate of the glass of the lower die; then a second ultrasonic vibration device connected with the upper die is started to apply ultrasonic longitudinal vibration to the upper die, the vibration parameters are the same as those of the first ultrasonic vibration device, and the vibration application time is t3Completely filling the space between the upper and lower molds and the glass, wherein the time for applying ultrasonic vibration to the lower mold is (t)2+t3)s；tz＝90～120s，t1＝20～30s，t2＝30～40s，t3＝40～50s；
Step three, annealing: in the annealing stage, the first ultrasonic vibration device and the second ultrasonic vibration device are closed, the temperature in the die pressing cavity is reduced to a preset annealing temperature, and pressure maintaining and annealing treatment are carried out under the condition of keeping the load;
step four, demolding pretreatment: performing secondary cooling for demolding, and reducing the temperature in the mold pressing cavity to the glass transition point temperature TgStarting a first ultrasonic vibration device and a second ultrasonic vibration device at the same time at the temperature of 50 +/-5 ℃ below zero to perform opposite ultrasonic vibration demoulding pretreatment, and keeping the vibration frequency within the low-frequency vibration frequency range of 15-20 KHz, the amplitude range of 2-4 mu m and the time of t4The demolding performance between the optical element and the mold is improved, and then the first ultrasonic vibration device and the second ultrasonic vibration device are closed; t is t4＝20～30s；
Step five, cooling: and in the cooling stage, the temperature of the mould pressing cavity is reduced again by using cold air provided by a water chiller to be cooled, and the mould is taken out after the mould is cooled to the room temperature to obtain the required mould pressing optical element.
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