CN114833360A

CN114833360A - Sectional type ultra-precise turning method for TIR lens

Info

Publication number: CN114833360A
Application number: CN202210459622.5A
Authority: CN
Inventors: 王占山; 余俊; 王一凡
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2022-04-28
Filing date: 2022-04-28
Publication date: 2022-08-02
Anticipated expiration: 2042-04-28
Also published as: CN114833360B

Abstract

The invention relates to a sectional type ultra-precise turning method of a TIR lens, which comprises the following steps: segmenting the TIR lens model to obtain a first part model and a second part model; modifying the first component model and the second component model to obtain a corresponding first blank and a second blank; turning a second cutting conical surface based on the second blank to obtain a second part; based on the first blank, turning to form a first positioning reference surface and a first optical surface; based on the processed first blank, further turning to obtain a first cutting conical surface to obtain a first part; gluing the first part and the second part along the first and the second conical dividing surfaces to ensure that the symmetry axes of the two parts are superposed to obtain a completely unprocessed TIR lens main body; and turning the rest optical surfaces of the TIR lens main body to obtain the finished TIR lens. Compared with the prior art, the method can solve the problem of acute angle processing in the TIR lens prototype, and has the advantages of low processing cost and short processing period.

Description

Sectional type ultra-precise turning method for TIR lens

Technical Field

The invention relates to the technical field of TIR lens processing, in particular to a sectional type ultra-precise turning method for a TIR lens.

Background

A tir (total internal reflection) lens is a commonly used Light Emitting Diode (LED) collimator, which can collimate light emitted from an LED light source to improve its remote irradiation capability.

At present, the general processing method of the TIR lens is injection molding, specifically, molten plastic is injected into a TIR mold by using pressure, and is cooled and molded to obtain the TIR lens. The method is suitable for mass production, but has the defects of long period and high cost for the preparation of engineering prototypes.

Diamond single point turning is a method for rapidly preparing a prototype of an optical element, but the tool geometry limits the processing of the TIR concave acute angle, i.e. the acute angle in the prototype of the TIR lens cannot be processed.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a sectional type ultra-precise turning method for a TIR lens, which can solve the problem of acute angle processing in a TIR lens prototype, and simultaneously reduce the processing cost and shorten the processing period.

The purpose of the invention can be realized by the following technical scheme: a sectional type ultra-precise turning method for a TIR lens comprises the following steps:

s1, segmenting the TIR lens model to obtain a first component model and a second component model;

s2, respectively modifying the first component model and the second component model to obtain a corresponding first blank and a second blank;

s3, turning a corresponding second cutting conical surface based on the second blank to obtain a second component;

s4, turning and processing a corresponding first positioning reference surface and a first optical surface based on the first blank;

s5, further turning and machining a corresponding first cutting conical surface based on the first blank machined in the step S4 to obtain a first part;

s6, gluing the first part and the second part along the first and the second conical dividing surfaces to ensure that the symmetry axes of the two parts are superposed to obtain a TIR lens body which is not processed completely;

and S7, turning the rest optical surfaces of the TIR lens main body to obtain the finished TIR lens.

Further, the TIR lens model in step S1 includes a first surface, a second surface, a third surface, a fourth surface, and a fifth surface, where the first surface is a concave bottom conical surface, the second surface is a concave inner cylindrical surface, the third surface is a TIR outer total reflection surface, and the fourth surface and the fifth surface are TIR rear segmented curved surfaces.

Further, the step S1 is to segment the TIR lens model along a tangential extended taper at the boundary of the first surface and the second surface.

Further, the step S2 specifically includes the following steps:

s21, for the first part model, supplementing the volume at the dividing interface to form a positioning platform a, cutting off the set volume at the end to form a positioning platform b, and stretching the rest surfaces outwards to complement the subsequent turning allowance to obtain a first blank;

and S22, aiming at the second part model, stretching the sectional surface of the light outlet to supplement the positioning platform c, and stretching the other surfaces outwards to supplement the subsequent turning allowance, so as to obtain a second blank.

Further, the specific process of step S3 is as follows: and turning the second blank on the disc by taking the positioning platform c as a positioning reference to obtain a conical surface of the second blank, namely a second cutting conical surface, so as to obtain a second part.

Further, the specific process of step S4 is as follows: and turning the positioning platform b by taking the positioning platform a as a positioning reference to obtain a first positioning reference surface and a first optical surface.

Further, the specific process of step S5 is as follows: and turning the first blank on the disc by taking the positioning platform b as a positioning reference to obtain a first part.

Further, the specific process of step S6 is as follows: placing the second part into a vessel by taking the positioning platform c as the bottom;

the conical surface downwards places the first part above the second part, so that the first division conical surface and the second division conical surface are attached, and the symmetry axes of the first part and the second part are superposed;

injecting light curing glue into the vessel to enable the liquid level to be higher than the first cutting conical surface and the second cutting conical surface to be attached to the obtained outer contour line;

and after glue is sucked into the gap between the first conical dividing surface and the second conical dividing surface through capillary action, taking out the TIR lens main body obtained by combining the first component and the second component, confirming that no bubble exists in the sucked glue, and finally, irradiating an ultraviolet lamp to harden and fix the sucked glue.

Further, in the steps S3, S4, and S5, the upper disc process before the turning process is: adhering a positioning platform opposite to the surface to be processed to a base tool, and then loading the base tool and the blank together;

the surface shape precision of the part plane opposite to the tool is better than 0.5 mu m when the disc is loaded;

when the surfaces of the workpiece to be machined are turned, the surface shape precision of each machined surface is within 1 mu m, and the roughness is within Rq 5 nm.

Further, the specific process of step S7 is:

and (3) taking the positioning platform b as a positioning reference, hanging the TIR lens main body on the disc, wherein the disc hanging process needs to ensure that the position error between the symmetry axis of the TIR lens main body and the lathe spindle is less than 0.5 mu m, and then turning and processing the segmented curved surfaces of the fourth surface and the fifth surface of the TIR lens main body.

Compared with the prior art, the invention has the following advantages:

1) the processing cost is low, and the cycle is short: the common TIR lens preparation and processing method is compression molding and injection molding, and a proper mold is designed according to a TIR lens model, so that the mold is processed ultra-precisely, and thermoplastic plastics are made into a designed TIR product by using an injection molding machine. The invention obtains two component models by segmenting the TIR lens model; then modifying the part model and processing a corresponding blank; then, turning a corresponding segmentation conical surface ultra-precisely; and finally, gluing the two parts along the two divided conical surfaces and turning the rest optical surfaces ultraprecisely. Therefore, the TIR lens finished product can be directly processed in an ultraprecise mode, the processing technology is greatly simplified for the preparation of an evaluation prototype, and the processing cost and the processing period are reduced.

2) The processing feasibility is high: for the general ultra-precision machining process, the internal depression acute angle which cannot be machined is limited by the geometric shape and the posture of a cutter, but the method adopts a segmented machining and gluing mode, and segments the TIR lens model by utilizing the tangential extension cone at the junction of the first surface and the second surface of the TIR lens model, so that the direct machining of the TIR lens product can be reliably realized, and the problem that the depression acute angle in a TIR lens prototype cannot be machined is solved.

Drawings

FIG. 1 is a schematic flow diagram of the process of the present invention;

FIG. 2 is a schematic diagram of a TIR lens model and its segmentation;

FIG. 3a is a schematic view of a first blank modification of the first part;

FIG. 3b is a schematic view of a second blank modification of the second part;

FIG. 4 is a schematic view of the gluing of a first part to a second part;

FIG. 5a is a schematic view of a first blank and a second blank;

FIG. 5b is a diagram of a TIR lens product;

the symbols in the figure illustrate: 1. a TIR lens model, 2, a tangential extension cone, 3, a first part, 4, a second part, 5, a first blank, 6, a second blank, 7, a TIR lens product, 8, an outer contour line, 101, a first surface, 102, a second surface, 103, a third surface, 104, a fourth surface, 105, a fifth surface, 301, a first division cone, 302, a first positioning reference surface, 303/304, a first optical surface, 501, a positioning platform a, 502, a positioning platform b, 401/402, a segmentation surface, 403, a second division cone, 601, a positioning platform c, 602, a second blank cone.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

Examples

As shown in fig. 1, a sectional type ultra-precision turning method for TIR lens includes the following steps:

s3, turning a corresponding second cutting conical surface based on the second blank to obtain a second part;

In step S1, as shown in fig. 2, the TIR lens model (1) includes a first surface (101), a second surface (102), a third surface (103), a fourth surface (104), and a fifth surface (105). The first surface (101) is a concave bottom conical surface, the vertex angle is about 108 degrees, the second surface (102) is a concave inner cylindrical surface, the diameter is 20mm, the length is 13.5mm, the third surface (103) is a total reflection surface on the outer side of the TIR, the surface type is a quadric surface, the diameter range is 25 mm-40 mm, the fourth surface (104) and the fifth surface (105) are sectional curved surfaces behind the TIR and are respectively a spherical surface and a quadric surface, and the rise is 1.9 mm. In this example, the TIR lens is made of PMMA, has a refractive index of about 1.5, and a density of about 1.15 to about 1.19g/cm 3.

Due to the acute angle of the inner part of the recess being about 54 degrees, a sectional machining method is adopted. And (3) dividing the TIR lens model (1) along a tangential extending conical surface (2) at the junction of the first surface (101) and the second surface (102), namely segmenting the TIR lens (1) along the conical surface (2) formed by the acute internal depression angle which cannot be machined under the limitation of the machining mode to obtain a first component model and a second component model.

In step S2, a positioning platform and a machining allowance are added to the segmented first part model and the segmented second part model to obtain a first blank (5) and a second blank (6). Specifically, as shown in fig. 3a and 3b, for the first part model, a positioning platform a (501) is formed by supplementing part of the volume at the first segmentation conical surface (301), and a positioning platform b (502) is formed by cutting off the end part of the volume, and the optical surface corresponding to the cut-off material does not participate in light collimation; for the second component model, the segment plane (401) (402) of the light exit is stretched and supplemented as a positioning platform c (601).

In addition, aiming at the first part model and the second part model, respectively stretching outwards on the corresponding other surfaces to complement ultra-precise turning allowance, wherein the unidirectional allowance is 150 mu m, so as to obtain a first blank (5) and a second blank (6), and then processing the blanks by using a numerical control lathe.

In step S3, a second cutting taper (403) of the second part (4) is ultra-precisely turned, specifically, a positioning platform c (601) is used as a positioning reference, a second blank (6) is put on a disc, the positioning platform opposite to the surface to be processed is adhered to a tool, then the tool and the part are put on the disc together, the taper (602) of the second blank (6) is ultra-precisely turned to obtain the second cutting taper (403), wherein the accuracy of the surface of the part plane opposite to the tool during the disc putting is better than 0.5 μm, the thickness of the remaining second blank (6) is measured in situ by using an optical probe to meet the requirement of the thickness of the machining allowance, and then the second part (4) after the machining is put on the disc for standby.

In step S4, the first positioning reference surface 302 and the first

optical surfaces

303 and 304 of the first member 3 facing the self-dividing tapered surface are ultra-precisely turned. Specifically, a positioning platform a (501) is used as a positioning reference, a first blank (5) is hung on a plate, a positioning platform b (502) is turned ultraprecisely, a first positioning reference surface (302) is obtained, and first optical surfaces (303) and (304) are turned ultraprecisely. And (3) subsequently processing a first cutting conical surface (301) by coiling the processed first blank (5).

In step S5, the first divided taper (301) of the first member (3) is ultra-precisely turned. Specifically, the tool is put on a plate, the surface of the first component (3) is positioned on the ultra-precision machining tool, the positioning platform b (502) and the first optical surface (304) are used as positioning references, the first blank (5) is placed on the tool, the first blank (5) is fixed through vacuum suction, and the first cutting conical surface (301) of the first component (3) is obtained through ultra-precision turning. And (4) taking the first processed component (3) and the tool down together.

In step S6, as shown in fig. 4, the first member (3) and the second member (4) are glued along the first cutting taper surface (301) and the second cutting taper surface (403). Specifically, the positioning platform c (601) is used as the bottom, the second part (4) is placed into a vessel, the first part (3) is placed on the second part (4) with the conical surface facing downwards, the two dividing conical surfaces (301) and (403) are attached, and the symmetry axes of the two parts are overlapped; injecting light curing glue into the vessel to enable the liquid level to be higher than the liquid level of the conical surface and to be attached to the obtained outer contour line (8); after the glue is absorbed into the gap between the two conical surfaces through capillary action, the TIR main body obtained by combining the two parts is taken out, no bubble is generated in the absorbed glue, and the glue is solidified by an ultraviolet lamp. It should be noted that the tooling of step S5 is not removed during the gluing process.

In step S7, after the gluing is completed, the remaining optical surfaces (401), (402), i.e. the fourth surface (104) and the fifth surface (105) of the TIR lens body are turned into piecewise curved surfaces. Specifically, the obtained TIR main body and the tool which is not removed are put on a disc together, and the position error between the symmetry axis and the main axis of the TIR lens main body is ensured to be less than 0.5 μm by an optical probe in-situ detection mode. And (3) turning the fourth surface (104) and the fifth surface (105) of the TIR lens body into segmented curved surfaces in an ultra-precise mode.

In this embodiment, the surface shape precision of each optical surface of the obtained TIR lens is within 1 μm, and the roughness is within Rq 5 nm.

Finally, as shown in fig. 5a and 5b, the first blank (5) and the second blank (6) are turned and glued ultra-precisely to obtain the TIR lens finished product (7).

In summary, the technical scheme is that a TIR lens model (1) is divided to obtain two part models, specifically, the TIR lens model (1) is divided along a conical surface (2) formed by extending the TIR lens model in an acute angle tangential direction to obtain a first part model comprising a total reflection surface and a concave side wall and a second part model comprising a conical surface and a rear surface; modifying the part model and processing blanks (5) and (6), specifically modifying the model according to the optical processing allowance and the processing fixing requirement to obtain a first blank (5) and a second blank (6) and processing the first blank and the second blank; ultra-precisely turning a dividing conical surface (403) of the second component (4), and specifically processing the dividing conical surface by taking a rear positioning surface of the second component (4) as a reference; ultra-precisely turning a positioning reference surface (302) and an optical surface (303) (304) of the first component (3) opposite to the self-dividing conical surface, and specifically, taking a rear positioning surface of the first component (3) as a reference, and carrying out diamond single-point turning optical processing on the related optical surface and a front positioning surface; then, turning a dividing conical surface (301) of the first component (3) ultra-precisely, and specifically processing the dividing conical surface by taking the front positioning surface of the first component as a reference; then, the first component (3) and the second component (4) are glued along the conical surfaces (301) and (403); finally, the remaining optical surfaces (104), (105) are ultra-precisely turned, specifically, the rear optical surface is machined with reference to the front locating surface of the first component.

The technical scheme realizes the sectional type ultra-precise turning method of the TIR lens, can effectively solve the problem of acute angle processing in a TIR lens prototype, and has the advantages of low cost, short period and the like.

Claims

1. A sectional type ultra-precise turning method for a TIR lens is characterized by comprising the following steps:

s1, segmenting the TIR lens model (1) to obtain a first component (3) model and a second component (4) model;

s2, respectively modifying the first component (3) model and the second component (4) model to obtain a corresponding first blank (5) and a corresponding second blank (6);

s3, turning a corresponding second cutting conical surface (403) based on the second blank (6) to obtain a second component (4);

s4, turning and machining a corresponding first positioning reference surface (302) and a first optical surface (303/304) on the basis of the first blank (5);

s5, based on the first blank (5) processed in the step S4, further turning a corresponding first dividing conical surface (301) to obtain a first component (3);

s6, gluing the first part (3) and the second part (4) along the first division conical surface (301) and the second division conical surface (403), and overlapping the symmetry axes of the two parts to obtain a completely unprocessed TIR lens main body;

and S7, turning the rest optical surface of the TIR lens body to obtain a finished TIR lens (7).

2. The sectional ultra-precision turning method for the TIR lens according to claim 1, wherein the TIR lens model (1) in the step S1 comprises a first surface (101), a second surface (102), a third surface (103), a fourth surface (104), and a fifth surface (105), the first surface (101) is a concave bottom cone surface, the second surface (102) is a concave inner cylindrical surface, the third surface (103) is a TIR outer total reflection surface, and the fourth surface (104) and the fifth surface (105) are TIR rear sectional curved surfaces.

3. The segmented ultra-precision turning method for the TIR lens according to claim 2, wherein the step S1 is to segment the TIR lens model (1) along the tangential extended taper (2) at the boundary of the first surface (101) and the second surface (102).

4. The segmented ultra-precise turning method for the TIR lens according to claim 2, wherein the step S2 specifically comprises the following steps:

s21, supplementing volume at a partition interface to form a positioning platform a (501), cutting off set volume at an end to form a positioning platform b (502), and stretching the rest surfaces outwards to complement subsequent turning allowance to obtain a first blank (5) aiming at the first component (3) model;

s22, aiming at the second component (4) model, the subsection surface (401/402) of the light outlet is stretched and supplemented to be a positioning platform c (601), and the rest surfaces are stretched outwards to supplement the subsequent turning allowance, so that a second blank (6) is obtained.

5. The segmented ultra-precise turning method for the TIR lens according to claim 4, wherein the specific process of the step S3 is as follows: and taking the positioning platform c (601) as a positioning reference, hanging the second blank (6) on a disc, and turning a conical surface of the second blank (6), namely a second cutting conical surface (403) to obtain the second component (4).

6. The segmented ultra-precise turning method for the TIR lens according to claim 5, wherein the specific process of the step S4 is as follows: and taking the positioning platform a (501) as a positioning reference, hanging the first blank (5) on a plate, and turning the positioning platform b (502) to obtain a first positioning reference surface (302) and a first optical surface (303/304).

7. The segmented ultra-precise turning method for the TIR lens according to claim 6, wherein the specific process of the step S5 is as follows: and taking the positioning platform b (502) as a positioning reference, hanging the first blank (5) on a plate, and turning to obtain a first division conical surface (301) to obtain the first component (3).

8. The segmented ultra-precise turning method for the TIR lens according to claim 7, wherein the specific process of the step S6 is as follows: placing the second part (4) into a vessel by taking the positioning platform c (601) as a bottom;

the conical surface downwards places the first component (3) above the second component (4), so that the first division conical surface (301) and the second division conical surface (403) are attached, and the symmetry axes of the first component (3) and the second component (4) are superposed;

injecting light curing glue into the vessel to enable the liquid level to be higher than the first division conical surface (301) and the second division conical surface (403) to be attached to the obtained outer contour line (8);

and after glue is sucked into the gap between the first division conical surface (301) and the second division conical surface (403) through capillary action, taking out the TIR lens body obtained by combining the first part (3) and the second part (4), confirming that no bubble exists in the sucked glue, and finally, irradiating an ultraviolet lamp to harden and fix the sucked glue.

9. The segmented ultra-precise turning method for the TIR lens according to claim 7, wherein in the steps S3, S4 and S5, the disc-feeding process before turning is as follows: adhering a positioning platform opposite to the surface to be processed to a base tool, and then loading the base tool and the blank together;

10. The segmented ultra-precise turning method for the TIR lens according to claim 9, wherein the specific process of the step S7 is as follows:

and (3) taking the positioning platform b (502) as a positioning reference, hanging the TIR lens main body on a disc, wherein the disc hanging process needs to ensure that the position error between the symmetry axis of the TIR lens main body and the lathe spindle is less than 0.5 mu m, and then turning and processing the segmented curved surfaces of the fourth surface (104) and the fifth surface (105) of the TIR lens main body.