Fresnel lens manufacturing method, injection molding die device used by same and manufactured Fresnel lensTechnical Field
The present invention relates to a method for manufacturing a fresnel lens, an injection molding die apparatus used in the method, and a fresnel lens manufactured by the method, and more particularly, to a method for manufacturing a fresnel lens, an injection molding die apparatus used in the method, and a fresnel lens manufactured by the apparatus.
Background
Fresnel lenses, also known as screw lenses, are characterized by their optical properties of short focal length, being more material-saving and lighter than conventional lenses. The fresnel lens is thinner than earlier lens designs and therefore delivers more light, and therefore the light source is more efficient in directing light farther away after being refracted through the fresnel lens.
Fresnel lenses are widely used in lighthouse projection navigation lights, lenses for projection film projectors, screens for rear projection displays, and headlights of automobiles, and are the most widely used lenses.
Most optical lenses are manufactured by injection molding with a mold, and conventional fresnel lenses are mainly manufactured by this method, and in general, the fresnel lenses are formed by processing thermoplastic plastic by an injection molding machine. However, in the existing fresnel lens mold, the temperature rise of the mold is slow, and the temperature of each part of the mold is uneven, so that the flow speed of the thermoplastic plastic in the mold cavity is different, and thus the molding cycle is too long, which causes the surface of the fresnel lens to be easily subjected to defect flow marks and air lines during the injection molding process, and finally the surface of the fresnel lens cannot achieve the effect of a sufficiently high light mirror surface. In addition, because of the temperature unevenness of each part of the mold during processing, the plastic material with lower temperature is cooled and formed in advance, so that Short Shot (Short Shot) defects are generated at the sharp parts of the fresnel lens, and the interior of the fresnel lens containing the Short Shot defects is accompanied with the problem of stress concentration, thereby further influencing optical imaging and seriously influencing the quality of the fresnel lens.
Referring to fig. 18, fig. 18 shows aconventional fresnel lens 90 with short-shot defects, in which thetips 91 of the saw teeth and thegrooves 92 between adjacent saw teeth are not perfectly sharp but have rounded blunt shapes under an electron microscope with 15 times optical magnification due to insufficient filling of the plastic material.
Up to now, there has been no method for manufacturing serrations and grooves of fresnel lenses having a sharp shape under an electron microscope with an optical magnification of more than 15 times.
Disclosure of Invention
The inventor of the present invention has developed a method for manufacturing a fresnel lens, an injection molding mold device used in the manufacturing process, and a fresnel lens manufactured by the method, in view of the disadvantages that the local filling of the cavity is insufficient due to the uneven cooling and heating of each part of the mold during the injection molding process, and the sharpness of the sawtooth part of the finished fresnel lens is insufficient, thereby affecting the optical quality.
The invention mainly aims to provide a manufacturing method of a Fresnel lens, an injection molding die device used by the manufacturing method and the Fresnel lens manufactured by the manufacturing method. The manufacturing method is characterized in that the plastic material can be fully filled into a cavity in a die by carrying out a rapid cooling and rapid heating treatment step on the thermoplastic plastic material, so that the manufactured Fresnel lens generates a sufficiently sharp structure on the sharp ends of the saw tooth parts and in the grooves, and the surface of the Fresnel lens has the effect of a high-light mirror surface, thereby improving the optical quality of the Fresnel lens.
In order to achieve the above object, the method for manufacturing a fresnel lens using a sharp cooling and heating mold core of the present invention comprises the following steps:
a rapid heating step, injecting high heat fluid into at least one mold waterway in the Fresnel lens injection molding mold device to rapidly heat to the temperature at which the thermoplastic plastic material can flow;
an injection step of injecting a liquid thermoplastic material into a mold cavity in the Fresnel lens injection molding mold device;
a transfer printing step, pressurizing the liquid thermoplastic plastic material in the mold cavity by using at least one pair of mold cores so as to enable the thermoplastic plastic material to generate a Fresnel lens structure; and
and a rapid cooling molding step, namely injecting low-temperature fluid into a mold water path in the Fresnel lens injection molding mold device to rapidly cool the liquid thermoplastic material in the mold cavity and cool and solidify the liquid thermoplastic material to form the Fresnel lens.
The Fresnel lens injection molding mold device and the related manufacturing method adopt the first mold waterway and the second mold waterway to inject hot steam, hot water or cold water into the first mold waterway and the second mold waterway so as to rapidly and uniformly heat or cool the female mold and the male mold, so that the temperature of each part of the plastic material in the mold cavity is rapidly, uniformly and uniformly raised and lowered, the surface of the Fresnel lens is prevented from generating defect flow marks and air lines due to overlong injection molding process time, in addition, the uniform temperature control can prevent the thermoplastic material part from being cooled and solidified in advance to cause short shot phenomenon, and the sharpness of the sharp part of the Fresnel lens can be improved, thereby improving the optical quality of the Fresnel lens.
In an embodiment of the invention, the mold water path is a first mold water path in a female mold of the fresnel lens injection molding mold device.
In an embodiment of the invention, the mold water path is a second mold water path in a male mold of the fresnel lens injection molding mold apparatus.
In an embodiment of the invention, the mold water path refers to a first mold water path in a female mold and a second mold water path in a male mold of the fresnel lens injection molding mold device.
In an embodiment of the present invention, in the rapid heating step, a rapid heating and cooling mold temperature controller is used to input high-temperature steam into the mold water path for rapid heating.
In an embodiment of the present invention, in the rapid cooling and forming step, a rapid cooling and heating mold temperature controller is used to input low temperature water into the mold water path for rapid cooling.
In an embodiment of the invention, in the injecting step, a plastic injection molding machine is used to inject plastic into the fresnel lens injection molding device.
Another objective of the present invention is to provide a fresnel lens injection molding die apparatus suitable for the above manufacturing method, which includes:
the first assembling groove is formed in the female die, a first die water channel is formed in the female die, and a first die cavity communicated with the first assembling groove is formed in one surface of the female die;
a male mold, which is connected with the female mold and can move relative to the female mold to be close to or far away from the female mold, at least one second assembly groove aligned and matched with the corresponding first assembly groove is formed on the male mold, a second mold cavity communicated with the second assembly groove is formed on one surface of the male mold, and the second mold cavity and the first mold cavity jointly form a mold cavity;
at least one cavity insert which is respectively arranged in the corresponding first assembling grooves; and
at least one male mold core is respectively arranged in the corresponding second assembling grooves and matched with the female mold core.
In an embodiment of the present invention, a second mold waterway is formed in the male mold.
In an embodiment of the invention, the first mold waterway and the second mold waterway are criss-cross.
In an embodiment of the invention, the female mold has a female mold pad and a female mold frame, at least one of the first assembling groove, the first mold waterway and the first mold cavity is formed in the female mold pad, and the female mold frame is hollow and is sleeved on the female mold pad.
In an embodiment of the invention, the male mold has a male mold lining block and a male mold outer frame, at least one of the second assembly groove, the second mold waterway and the second mold cavity is formed in the male mold lining block, and the male mold outer frame is hollow and is sleeved on the male mold lining block.
In an embodiment of the invention, the first assembling grooves are plural, and the cavity insert is plural; the first mold cavity is provided with a first main plastic runner and a plurality of first branch plastic runners, and the plurality of first branch plastic runners extend outwards from the first main plastic runner and are respectively communicated with the plurality of first assembling grooves.
In an embodiment of the invention, the second assembling grooves are plural, and the core insert is plural; the second mold cavity is provided with a second main plastic runner and a plurality of second branch plastic runners, the second main plastic runner corresponds to the first main plastic runner, the plurality of second branch plastic runners respectively correspond to the plurality of first branch plastic runners, extend outwards from the second main plastic runner and are respectively communicated with the plurality of second assembly grooves.
In an embodiment of the invention, two opposite vertexes of the first mold water path are two first confluence points, and each first confluence point forms a first main branch passage which extends to the outside of the master mold pad.
In an embodiment of the invention, two first sub-branch passages are formed at each first confluence point of the first mold water passage, and the two first sub-branch passages extend to the outside of the master mold pad.
In an embodiment of the invention, two opposite vertexes of the second mold water path are two second confluence points, and each second confluence point forms a second main branch passage which extends to the outside of the male mold pad.
In an embodiment of the invention, two second sub-branch passages are formed at each second confluence point of the second mold water channel, and the two second sub-branch passages extend to the outside of the male mold pad.
In an embodiment of the invention, a first fresnel-structure rotating surface is formed on an inner side surface of the cavity, and a second fresnel-structure rotating surface is formed on an inner side surface of the core.
In an embodiment of the present invention, a first cavity water path is formed inside the cavity.
In an embodiment of the present invention, a second cavity water path is formed inside the core.
In an embodiment of the invention, two opposite vertexes of the first cavity water path of the cavity are two first connection points, and two first yielding through holes are formed through a first sealing gasket disposed on the cavity and respectively connected to the two first connection points.
In an embodiment of the invention, two opposite vertexes of the second cavity water path of the core are two second communication points, and a second gasket disposed on the core is penetrated to form two second yielding through holes respectively connected to the two second communication points.
In an embodiment of the invention, the fresnel lens injection molding mold device further includes a fixed substrate and a movable substrate, the fixed substrate and the female mold are fixed to each other, the fixed substrate is provided with at least one first mold core pipeline set, each first mold core pipeline set has a first inflow pipe and a first outflow pipe to be respectively connected to two first yielding through holes of the corresponding female mold core; the movable base plate and the male die are fixed with each other, at least one second die core pipeline set is arranged on the movable base plate, and each second die core pipeline set is provided with a second inflow pipe and a second outflow pipe which are respectively connected to two second abdicating through holes of the corresponding male die core.
Still another object of the present invention is to provide a fresnel lens manufactured by the above manufacturing method, including:
the Fresnel lens comprises a lens body and a plurality of concentric annular ribs, wherein the concentric annular ribs are formed on the lens body and are arranged in a concentric circle mode, on a side cross section passing through a central shaft of the Fresnel lens, the concentric annular ribs respectively have sawtooth cross sections, and the sawtooth cross sections are in a left-right symmetrical shape based on the central shaft;
wherein the tips of the saw-tooth cross-sections of the concentric annular ribs appear sharp instead of rounded under observation under a microscope at a magnification of up to 150.
In an embodiment of the present invention, a saw tooth groove section is formed between any two adjacent saw tooth sections, and the bottom of the saw tooth groove section is sharp rather than rounded under the observation of a microscope with a magnification of up to 150.
The manufacturing method of the invention can fully fill the plastic material into the cavity in the die by carrying out the treatment steps of rapid cooling and rapid heating on the thermoplastic plastic material, thereby leading the manufactured Fresnel lens to generate a sufficiently sharp structure on the sharp end of the sawtooth part and in the groove, leading the surface of the Fresnel lens to have the effect of a high light mirror surface and further improving the optical quality of the Fresnel lens.
Drawings
Fig. 1 is a perspective view of a fresnel lens injection molding die apparatus according to the present invention.
Fig. 2 is a sectional view of a fresnel lens injection molding die apparatus according to the present invention.
Fig. 3 is a three-dimensional exploded view of the female mold, the female mold insert, the male mold and the male mold insert of the fresnel lens injection molding mold device according to the present invention.
Fig. 4 is an exploded perspective view of a master mold pad and a master mold core in the fresnel lens injection molding mold apparatus of the present invention.
Fig. 5 is an exploded perspective view of a cavity insert of the fresnel lens injection molding apparatus of the present invention.
Fig. 6 is an exploded perspective view of a core insert and a core insert in the fresnel lens injection molding apparatus of the present invention.
Fig. 7 is an exploded perspective view of a core insert in the fresnel lens injection molding apparatus of the present invention.
Fig. 8 is a perspective view of the plastic material in the cavity of the fresnel lens injection molding die apparatus according to the present invention.
Fig. 9 is a schematic plan view of a master mold pad in the fresnel lens injection molding apparatus according to the present invention.
Fig. 10 is a schematic plan view of a male mold pad in the fresnel lens injection molding apparatus according to the present invention.
Fig. 11 is a schematic plan view of a cavity insert in the fresnel lens injection molding apparatus according to the present invention.
Fig. 12 is a schematic plan view of a core insert and a waterway of an internal mold in the fresnel lens injection molding mold device according to the present invention.
Fig. 13 is a perspective view of the mold water path and the mold core pipe set along the overlapping direction of the female mold and the male mold in the fresnel lens injection molding mold device according to the present invention.
Fig. 14 is a cross-sectional view of a fresnel lens of the present invention taken along a central axis.
Fig. 15 is a schematic enlarged cross-sectional view of a fresnel lens of the present invention under an electron microscope at 150 x optical magnification.
Fig. 16 is a block diagram of a fresnel lens injection molding mold apparatus, a rapid cooling and heating mold temperature controller, and a plastic injection molding machine according to the present invention.
FIG. 17 is a flowchart illustrating steps of a method for manufacturing a Fresnel lens according to the present invention.
Fig. 18 is a schematic enlarged cross-sectional view of a conventional fresnel lens under an electron microscope at 15 times optical magnification.
[ notation ] to show
1 Fresnel lens ejection forming die device
2 temperature controller for rapid cooling and heating mould
3 plastic injection molding machine
10 female die and 11 female die outer frames
13master mold pad 130 first assembly groove
135 firstmould water path 1350 first confluence point
1351 firstmain branch path 1352 first sub branch path
136 firstmain plastic runner 137 first branch plastic runner
20 male die and 21 male die outer frame
23 malemold backing block 230 second assembly groove
235second mold waterway 2350 second confluence point
2351 secondmain branch path 2352 second secondary branch path
30cavity 300 first fresnel structure rotating surface
301first gasket seal 31, 32 first abdicating through hole
35 firstcore water path 350 first connection point
40core 400 second fresnel structure surface of revolution
401second sealing gasket 41, 42 second abdicating through hole
45second cavity waterway 450 second connection point
50 fixedbase plate 51 first inflow pipe
52 first outflow pipe
60 second inflow pipe ofmovable substrate 61
62 second outflow pipe
80Fresnel lens 80a Fresnel lens Plastic section
81 sawtooth lug section 811 tip
82 saw toothgroove cross section 821 bottom
C36 Main Plastic runner C37 Branch Plastic runner
90conventional fresnel lens 91 tip
92 groove
Detailed description of the invention
The invention will be further described with reference to specific embodiments, and the advantages and features of the invention will become apparent as the description proceeds. These examples are illustrative only and do not limit the scope of the present invention in any way. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention, and that such changes and modifications may be made without departing from the spirit and scope of the invention.
Referring to fig. 1 to 3 and fig. 16, a fresnel lens injectionmolding mold apparatus 1 of the present invention can be connected to a rapid cooling and heatingmold temperature controller 2 and a plasticinjection molding machine 3, and includes: afemale mold 10, amale mold 20, at least onefemale mold insert 30, at least onemale mold insert 40, a fixedbase plate 50, and amovable base plate 60.
Referring to fig. 4 and 9, at least onefirst assembly groove 130 is formed on thefemale mold 10, and a firstmold water passage 135 is formed in thefemale mold 10 for injecting hot steam, hot water or cold water injected by the rapid cooling and rapid heatingmold temperature controller 2, so as to rapidly and uniformly heat or cool thefemale mold 10. Thefirst mold waterway 135 may be quadrilateral, spiral, U-shaped, or any shape that may be uniformly distributed within themaster mold 10. The high-temperature hot steam can have a high temperature of 140 to 160 ℃, so that the good fluidity of the common thermoplastic plastic material can be maintained at the high temperature, and the temperature of the hot steam can be increased according to the condition; in addition, the temperature of the cold water can be 80 to 90 ℃, at which the common thermoplastic material can be cooled and solidified, and the temperature of the cold water can be increased or decreased according to the condition. A first cavity communicating with thefirst assembling groove 130 is formed on one side of thefemale mold 10 for theinjection molding machine 3 to inject the thermoplastic material therein. In addition, the temperature of the thermoplastic material of the plasticinjection molding machine 3 during the injection (also referred to as the material temperature) is typically 200 to 260 ℃.
In the preferred embodiment, thefemale mold 10 has afemale mold pad 13 and afemale mold frame 11, at least one of thefirst assembly groove 130, the firstmold water passage 135 and the first mold cavity is formed in thefemale mold pad 13, and thefemale mold frame 11 is hollow and is disposed on thefemale mold pad 13. The opposing vertices of thefirst mold waterway 135 are two first confluence points 1350, and each of the first confluence points 1350 forms a firstmain branch passage 1351, the firstmain branch passage 1351 extending beyond themaster pad 13. In addition, two firstsub-branch passages 1352 are formed in eachfirst confluence point 1350, and the two firstsub-branch passages 1352 extend to the outside of themaster pad 13. The firstmain branch passage 1351 may be connected to a line from the rapid cooling and heatingmold temperature controller 2 for injecting hot steam, hot water or cold water into themaster mold pad 13. The firstsecondary branch passageways 1352 may be screwed to seal off external lines and may be connected to thetemperature controller 2 from the chill and hot die in other situations.
Referring to fig. 6, 10 and 13, themale mold 20 and thefemale mold 10 are connected to each other and can move relative to thefemale mold 10 to abut against or move away from thefemale mold 10. A secondmold water path 235 is formed in themale mold 20 for injecting hot steam, hot water or cold water injected by the rapid cooling and rapid heatingmold temperature controller 2 therein, thereby rapidly and uniformly heating or cooling themale mold 20. Thesecond mold waterway 235 may be quadrilateral, spiral, U-shaped, or any shape that may be uniformly distributed within themale mold 20. Thesecond mold waterway 235 may be crosswise to thefirst mold waterway 135, as shown in fig. 13. At least onesecond assembling groove 230 aligned and matched with the corresponding first assemblinggroove 130 is formed on themale mold 20, and a second mold cavity communicated with thesecond assembling groove 230 is formed on one surface of themale mold 20 for theinjection molding machine 3 to inject the thermoplastic plastic material therein. The second mold cavity and the first mold cavity together form a mold cavity.
In the preferred embodiment, themale mold 20 has amale mold pad 23 and amale mold housing 21, at least one of thesecond assembly groove 230, thesecond mold waterway 235 and the second mold cavity is formed in themale mold pad 23, and themale mold housing 21 is hollow and is disposed on themale mold pad 23. The two opposite vertices of thesecond mold waterway 235 are two second confluence points 2350, eachsecond confluence point 2350 forming a secondmain branch passage 2351, the secondmain branch passage 2351 extending beyond themale mold pad 23. In addition, a secondsubsidiary branch passage 2352 is formed at eachsecond confluence point 2350 of thesecond mold waterway 235, and the secondsubsidiary branch passages 2352 extend beyond themale mold pad 23. The secondmain branch passage 2351 may be connected with a line from the rapid cooling and heatingmold temperature controller 2 for injecting hot steam, hot water or cold water into themale mold pad 23. The secondsecondary branch passageways 2352 may be screwed for sealing, not otherwise connected to external piping, or may be connected to thetemperature controller 2 from the rapid thermal quenching die in other situations.
Referring to fig. 4, 5 and 11, thecavity insert 30 is disposed in the corresponding first assemblinggroove 130. A first moldcore water path 35 is formed inside thecavity core 30 for injecting hot steam, hot water or cold water injected by the rapid cooling and rapid heatingmold temperature controller 2, so as to rapidly and uniformly heat or cool thecavity core 30. The firstmold core waterway 35 may be a quadrangle, a spiral, a U-shape, or any shape that may be uniformly distributed in thecavity 30. Two opposite vertexes of the firstcavity water path 35 are two first communication points 350, two first yielding throughholes 31, 32 are formed on afirst sealing gasket 301 disposed on thecavity 30, and the two first yielding throughholes 31, 32 are respectively connected to the two first communication points 350. In addition, a first fresnelstructure rotation surface 300, which may be aspheric, is formed on an inner side surface of thecavity 30. In addition, two bolts may be disposed on thecavity 30 to further fix thefirst sealing gasket 301 on thecavity 30.
Referring to fig. 6, 7 and 12, thecore insert 40 is disposed in the corresponding second assemblinggroove 230 and matched with thecavity insert 30. A secondcavity water channel 45 is formed inside thecore 40 for injecting hot steam, hot water or cold water injected by the rapid cooling and rapid heatingmold temperature controller 2, so as to rapidly and uniformly heat or cool the core 40. Thesecond core waterway 45 may be a quadrilateral, spiral, U-shaped, or any shape that may be uniformly distributed within thecore 40. Two opposite vertexes of the secondcavity water path 45 of the core 40 are two second communication points 450, two second yielding throughholes 41, 42 are formed through asecond sealing gasket 401 disposed on thecore 40, and the two second yielding throughholes 41, 42 are respectively connected to the two second communication points 450. In addition, a second fresnelstructure rotation surface 400 is formed on an inner side surface of thecore insert 40. The fresnel lens can be manufactured by embossing the first fresnel-structure rotating surface 300 and the second fresnel-structure rotating surface 400 onto the thermoplastic material surface in the mold cavity, respectively. In addition, two bolts may be disposed on thecore insert 40 to further fix thesecond sealing gasket 401 on thecore insert 40.
Referring to fig. 4, 6 and 8, in the preferred embodiment of the present invention, there are a plurality of first assemblinggrooves 130 and a plurality of cavity inserts 30; the first mold cavity has a firstmain plastic runner 136 and a plurality of firstbranch plastic runners 137, and the plurality of firstbranch plastic runners 137 extend outward from the firstmain plastic runner 136 and are respectively communicated with the plurality of first assemblinggrooves 130. In addition, there are a plurality of second assemblinggrooves 230, and a plurality of core inserts 40; the second mold cavity has a secondmain plastic runner 236 and a plurality of secondbranch plastic runners 237, the secondmain plastic runner 236 corresponds to the firstmain plastic runner 136, the plurality of secondbranch plastic runners 237 respectively correspond to the plurality of firstbranch plastic runners 137, and extend outward from the secondmain plastic runner 236 and respectively communicate with the plurality of second assemblinggrooves 230. By arranging the plurality offemale molds 30 andmale molds 40, the fresnel lens injectionmolding mold apparatus 1 can manufacture a plurality of fresnel lenses in a single processing procedure. The distribution of the plastic in the mold cavity is shown in fig. 8, which shows a main plastic runner C36, a plurality of branch plastic runners C37 connected to the main plastic runner C36, and a plurality of fresnellens plastic portions 80a located at the branch plastic runners. Hot water vapor, hot water or cold water is injected into the firstmold water passage 135 and the secondmold water passage 235 to uniformly cool and rapidly heat thefemale mold 10 and themale mold 20, so that the temperatures of the main plastic passage part C36, the branch plastic passage part C37 and the fresnel lensplastic part 80a can be uniformly raised and lowered, and the problem that the optical quality of the fresnel lens is reduced due to poor molding caused by over-low temperature of local plastic materials and solidification of the fresnel lens is avoided.
The fixedsubstrate 50 and thefemale mold 10 are fixed to each other, at least one first mold core pipeline set is disposed on the fixedsubstrate 50, and each first mold core pipeline set has afirst inflow pipe 51 and afirst outflow pipe 52 to be connected to two first yielding throughholes 31 and 32 of the correspondingfemale mold core 30, respectively. Thefirst inflow pipe 51 and thefirst outflow pipe 52 may be connected to the rapid cooling and heatingmold temperature controller 2, thereby injecting hot steam, hot water or cold water into thecavity insert 30.
Themovable substrate 60 and themale mold 20 are fixed to each other, at least one second mold core pipe set is disposed on themovable substrate 60, and each second mold core pipe set has asecond inflow pipe 61 and asecond outflow pipe 62 to be connected to the two second abdicating throughholes 41 and 42 of the correspondingmale mold core 40, respectively. Thesecond inflow pipe 61 and thesecond outflow pipe 62 may be connected to the rapid cooling and heatingmold temperature controller 2, thereby injecting hot steam, hot water or cold water into thecore insert 40.
Referring to fig. 1, 16 and 17, the method for manufacturing the fresnel lens using the fresnel lens injectionmolding mold apparatus 1 of the present invention includes: a rapid heating step S01, an injection step S02, a transfer step S03 and a rapid cooling forming step S04.
The rapid heating step S01 includes injecting a high heat fluid into at least one mold water path in the fresnel lens injectionmolding mold apparatus 1 to rapidly heat the mold to a temperature at which the thermoplastic material can flow. The at least one mold waterway may be thefirst mold waterway 135 alone in thefemale mold 10, thesecond mold waterway 235 alone in themale mold 20, or both thefirst mold waterway 135 and thesecond mold waterway 235. In the rapid heating step S01, the mold water path is supplied with high-temperature steam to perform rapid heating by the rapid cooling and rapid heatingmold temperature controller 2.
The injection step S02 includes injecting a liquid thermoplastic material into a cavity in the fresnel lensinjection molding apparatus 1. In the injection step S02, the thermoplastic plastic is injected into the fresnel lens injection molding die set 1 by the plasticinjection molding machine 3.
The transferring step S03 includes pressing the liquid thermoplastic material in the mold cavity with at least one pair of mold cores to generate fresnel lens structures in the thermoplastic material.
The rapid cooling molding step S04 includes injecting a low-temperature fluid into the mold core water path in the fresnel lens injectionmolding mold device 1 to rapidly cool the liquid thermoplastic material in the mold cavity and solidify the liquid thermoplastic material to form the fresnel lens. In the rapid cooling step S04, the mold core is quenched by inputting low-temperature water into the mold core water path through the rapid cooling and rapid heatingmold temperature controller 2.
Referring to fig. 14 and 15, thefresnel lens 80 manufactured by the manufacturing method of the present invention includes: the Fresnel lens comprises a lens body and a plurality of concentric annular rib parts, wherein the concentric annular rib parts are formed on the lens body and are arranged in a concentric circle mode, on the side section passing through the central axis of the Fresnel lens, the concentric annular rib parts are respectively insawtooth bump sections 81, thesawtooth bump sections 81 are distributed in a left-right symmetrical mode by taking the central axis as a reference, and asawtooth groove section 82 is arranged between any two adjacentsawtooth bump sections 81.
Under observation with a microscope at a magnification of up to 150, thetip 811 of the sawtooth bump section 81 of each concentric annular rib portion assumes a sharp shape instead of a rounded corner, and thebottom 821 of each sawtooth groove section 82 assumes a sharp shape instead of a rounded corner.
The invention has the following advantages:
1. the fresnel lens injectionmolding mold device 1 and the related manufacturing method of the fresnel lens of the present invention employ thefirst mold waterway 135 and thesecond mold waterway 235 to inject hot steam, hot water or cold water into them, so as to heat or cool thefemale mold 10 and themale mold 20 rapidly and uniformly, so that the temperature of each part of the plastic material in the mold cavity is raised and lowered rapidly, uniformly and uniformly, thereby avoiding the surface of the fresnel lens from generating defect flow marks and air marks due to too long time of the injection molding process, and in addition, uniform temperature control can avoid the short shot phenomenon due to the prior cooling and solidification of the thermoplastic material part, thereby improving the sharpness of the sharp part of the fresnel lens, and further improving the optical quality of the fresnel lens, as shown in fig. 15.
2. The firstmold water path 135 and the secondmold water path 235 of themale mold 20 and thefemale mold 10 are configured in a cross manner, so that the uniform temperature control performance of thefemale mold 10 and themale mold 20 is further improved, and the quality of the finished fresnel lens is improved.