TWI802839B - Method for manufacturing a mold core and using the mold core to manufacture lenses - Google Patents

Abstract

A method for manufacturing a mold core with an asymmetric curved surface, including the following steps: placing a mold core on the rotating shaft surface of a processing machine, wherein the mold core has a center axis not coaxial with an axis of the rotating shaft surface, and the mold core is not disposed on the position of the axis of the axis; rotating the rotating shaft surface of the processing machine; using the processing machine to process the mold core from three directions including the two-dimensional directions of the rotating shaft surface and the axial front and back of the rotating shaft surface simultaneously; Continue processing until the mold core with an asymmetric curved surface is produced.

Description

Mold core with free-form surface, manufacturing method thereof, and method for making lens and lens using the mold core

The present invention relates to a mold core with a free-form surface and its manufacturing method, as well as a method of using the mold core to manufacture lenses, especially a mold core manufactured by off-axis slow knife servo machining and a method of using the mold core to manufacture lenses.

Compared with traditional optical components, optical components with free-form surfaces can significantly simplify the structure of the optical system, reduce costs, and improve the performance of the optical system. However, it has high requirements for surface shape accuracy and surface roughness. In practical applications, the surface roughness generally needs to reach the nanometer level, and the requirement for contour accuracy also needs to reach the micron or even sub-micron level. The ultra-precision single-point diamond turning method can achieve high surface quality in one process and meet the surface quality requirements of the optical system for optical components, so it is widely used in the processing of optical components. The slow tool servo turning method has better acceleration and deceleration performance and a larger feed stroke, and can realize the processing of optical free-form surfaces with large amplitude and large curvature changes, such as for the processing of optical lens mold cores.

Please refer to FIG. 1A , which shows an example of a configuration of a slow-tool servo machining device 1 suitable for ultra-precision machining of free-form surfaces. The slow tool servo machining device 1 has a processing rotation axis surface 3, the processing rotation axis surface 3 has an axis C, a first axis surface direction X, and a second axis surface direction Y, and the first bed 2 controls the processing rotation axis surface 3 toward Move in X or Y direction. The processing tool 5 can be arranged on the second bed 4 different from the first bed 2, and can move in the Z direction perpendicular to the X and Y directions. The material 7 to be processed is disposed at a position adjacent to the axis C of the processing rotation axis surface 3, and is processed through an automatic processing program controlled by a computer.

Fig. 1B shows the top view of the cutting surface processed by the slow tool servo processing device 1 after the mold core material 10 is installed on the axis C of the processing rotation axis surface 3 in the traditional way, and the reference origin where the X and Y axes intersect in the figure O is usually the starting point of processing, and the processing traces formed by the processing path Acut spread across the cutting surface in the form of gradual extension from the reference origin O according to the preset processing path.

FIG. 1C shows a schematic diagram of a type of processing trace depth D of the mold core material 10 in FIG. 1B along the X axis, and C in the figure represents the reference origin O position relative to the axis C of the processing rotation axis surface 3 . As shown in the figure, near the reference origin O, for example, the depth of the processing traces between points a and b in the figure is particularly deep, while the depth of processing traces outside points a and b is not much different. Fig. 1D shows a schematic diagram of another embodiment of the processing trace depth D of the mold core material 10 in Fig. 1B along the X axis, which is opposite to the pattern in Fig. 1C, and the processing between points a' and b' in the figure The depth of the trace line is extremely shallow, but there is not much difference in the depth of the processed trace line beyond point a and point b.

For the mold core made by the above method, since the processing traces appearing near the axis C of the processing rotation axis surface often have a significant gap in depth with the processing traces of the surrounding parts, the optical effect of the produced lens be adversely affected. Therefore, how to avoid the shortcomings of the above-mentioned devices is a technical problem that needs to be solved. As shown in FIG. 1E , the height difference of the processing marks in the central area of the curved surface of the mold core after traditional slow tool servo processing is about 18 nanometers.

According to one aspect of the present invention, a mold core manufactured by off-axis slow tool servo machining and its manufacturing method are proposed, which can produce multiple mold cores with free-form surfaces at one time and improve production efficiency; and the corrugation errors at different positions on the curved surface tend to In the same way, the optical effect of the lens is greatly improved.

According to an embodiment of the present invention, a method for manufacturing a mold core with a free-form surface is proposed, the method comprising the following steps: a mold core workpiece is placed on a rotating shaft surface of a processing machine, and the mold core workpiece and the rotating shaft The central axis of the contact surface is not coaxial with the axis of the rotational axis surface. Then, rotate the rotating axis surface of the processing machine, and make the rotating axis surface and the processing tool relatively move in three dimensions such as the rotating axis, the radial direction, or the rotation of each axis for processing, and Continue processing until a mold core with a free-form surface is produced.

According to another embodiment of the present invention, a mold core with a free-form surface is proposed, which is produced by the above method, wherein the mold core includes a free-form surface with a plurality of processing lines, and the free-form surface does not have multiple concentric Center-shaped processing marks.

According to another embodiment of the present invention, a method for manufacturing a lens using the mold core produced by the above method and the lens produced by the method are proposed, including the following steps: heating a lens material, and then placing the heated lens material into Between a first mold core and a second mold core. The first mold core is provided with a free-form surface, and the free-form surface has a plurality of non-concentric processing marks. The lens material is then cooled to form it. And after the lens is molded, the lens is released from the first mold core and the second mold core to obtain a molded lens.

According to another embodiment of the present invention, a lens is provided, which is manufactured by the mold core manufactured by the above method.

The method proposed by the present invention for ultra-precisely machining free-form mold cores in an off-axis manner is suitable for the production of mold cores for optical lenses and has industrial applicability.

The invention proposed in this case can be fully understood by the following examples, so that those with ordinary knowledge in the technical field can complete it. However, the implementation of this case cannot be limited by the following examples. Those with ordinary knowledge in the technical field can still deduce other implementation modes according to the spirit of the embodiments disclosed in the specification, and these implementation modes still belong to the scope of the present invention.

Optical lens compression molding technology utilizes the continuous and reversible thermal processing property of glass from molten state to solid state. The glass and mold are heated and pressurized near the transition temperature Tg of the glass, and the mold core can be transformed into a solid state at one time. Optical glass is molded into optical lenses that meet the requirements of use. Because the optical glass molding method abandons the traditional rough grinding, fine grinding, polishing and centering edging and other processes, it can be formed directly at one time, which greatly saves materials, time, equipment and manpower, and can mold different shapes, especially In the manufacture of aspheric optical glass parts. In addition to glass materials, this method can also be used to make lenses of other materials. The lens material is, for example, glass nitrate. According to an embodiment, when using the mold core to manufacture a lens, the lens material may be heated first, and then the heated lens material is placed between a first mold core and a second mold core. A cavity can be formed between the first mold core and the second mold core, and the heated lens material is put into the cavity to fill the cavity. In the case of injection molding, the lens material is usually injected between the two mold cores under the condition of high speed and high pressure. Since at least one mold core has a free-form surface, and the free-form surface has a plurality of non-concentric processing marks, after cooling the lens material, the lens is released from the first mold core and the second mold core. , a molded lens with multiple non-concentric center-shaped processing marks on a free-form surface can be obtained. The need to apply precision polymer optics has become increasingly important in recent years. Due to the unique properties of both thermoplastics and injection molding processing techniques, polymer optics allow cost-effective combinations of optical surfaces and mounting features. The precision of injection molding depends on the surface precision of the mold core, especially the mold core used for injection molding of optical lenses.

Usually, the movable side and the fixed side of the injection molding mold set respectively include a component group with roughly the same structure, and the runner structure is a corresponding component group, but in another embodiment, it can be selectively embedded in the movable side template, Or it can also be used in the fixed side formwork, and the present invention is not limited thereto. Injection-molded lens materials are, for example, optical resins. In addition, the perforation at the center of the component group on the movable side can be used to accommodate mechanisms such as thimbles. The fixed side mold includes a fixed side template, a fixed side fixed plate (such as the first template), a fixed side pressing template, a fixed side mold core and a filling nozzle. The fixed plate on the fixed side is provided with an injection port to accept the injection of high-temperature fluid plastics. The fixed side formwork has a flow channel to provide a flow channel for high temperature flow plastic. The fixed side mold core has several mold cavities to accommodate high temperature flow plastics. The mold cavity has a specific shape, such as a polygonal, circular or elliptical cavity, and the high-temperature flowing plastic in the mold cavity is cooled and solidified to form the specific shape, and finally the lens is separated from the first mold core and the second mold The core is demolded to obtain the molded lens.

Please refer to FIG. 2 , which shows a schematic diagram of an embodiment of a manufacturing method for manufacturing a mold core with a free-form surface according to the present invention. With reference to Fig. 3, the present invention provides an eccentric jig 100 on which at least one mold core material 10 can be disposed, and the geometric central axis of each mold core material 10 is represented by C". When the eccentric jig 100 is installed In the processing rotation axis surface 3 on the slow tool servo machining device 1 as shown in Figure 1A, it can be seen that the axis C of the processing rotation axis surface 3 and the geometric central axis C" of each mold core material 10 are not coaxial, and Each mold core material 10 is also not located at the position of the axis C of the machining rotation axis surface 3, so it is arranged in an eccentric manner.

The position of the reference origin O of the eccentric jig 100 is at a position relative to the axis C, and the first bed 2 of the slow tool servo machining device 1 allows the eccentric jig 100 to be controlled by a computer program during the machining process. , and realize a two-dimensional processing path along the first axial direction X and axial direction Y; the second bed 4 can cooperate with the computer program to control the Z direction in real time, which is equivalent to processing the axis C of the rotating axis 3 forward or backward , the processing depth. In this way, as long as the data of the three-dimensional position of the eccentric jig 100 and the mold core material 10 disposed on it are known in advance, or the three-dimensional geometric relationship between the jig and the workpiece to be processed, the off-axis machining formula control of the present invention Next, the required free-form surfaces can be formed on multiple mold core materials 10 at one time by means of slow knife machining. The processing machine to which the present invention is applied may be a processing machine using a cutting tool such as a lathe, or a tool such as a grinding wheel.

The so-called three-axis machining mainly refers to rotating the rotating shaft surface of the processing machine, and making the rotating shaft surface and the processing tool move relative to each other in three directions, such as the axial direction and radial direction, for processing; it is not limited to The axis of rotation moves in a one-dimensional direction, a two-dimensional direction or a three-dimensional direction, as long as the relative movement of the two is in a three-dimensional direction. That is to say, the axis of rotation may move in a two-dimensional direction, while the processing tool moves in a one-dimensional direction, and the two constitute relative three-dimensional movement.

The so-called one-dimensional direction (one-dimensional direction) of the present invention refers to traditional X-axis, Y-axis, Z-axis, or X-axis rotation (A-axis), Y-axis rotation (B-axis), Z-axis rotation ( C axis). Two-dimensional direction movement or three-dimensional direction movement refers to movement or rotation of the above-mentioned two or three axes.

Before the actual processing, it is necessary to use fasteners such as positioning pins or screws to arrange the core material 10 on the relative position of the eccentric jig 100 away from the axis C that keeps the core material away from the machining rotation axis 3, in other words , the mold core material 10 must be placed far away from the reference origin O. The example in FIG. 2 shows that four mold core materials 10 are disposed on the eccentric jig 100 in an eccentric manner, and the number of mold core materials in practice is not limited thereto. As can be understood from the figure, the mold core materials 10 each have their central axes (not shown), and the central axes of these mold core materials 10 are not coaxial with the axis C of the machining rotation axis surface 3, and the mold core materials 10 are not on the same axis. The position of the axis C of the rotation axis surface 3 is processed.

The geometric profile of the eccentric jig 100 is known, so it can provide a positioning function, and then serve as the basic data for editing the off-axis machining formula used in the present invention. The off-axis machining formula can be executed by a computer to control the slow tool servo machining device 1 so that the machining tool 5 usually (but not limited to) starts from the reference origin O on the machining surface and gradually forms machining lines along the machining path Acut. Comparing the relative positions of Fig. 1C/1D and Fig. 2, it can be understood that since all mold core materials 10 are eccentrically away from the reference origin O, they are located in the area where the depth difference of the processing marks is not much different, similar to Fig. 1C/1D The location of the area outside point a and point b (point a' and point b'). Such an arrangement allows the mold core material 10 to avoid the area adjacent to the axis C on the machining rotation axis surface 3 , so there will be no obvious variation error of waviness.

In order to achieve special optical effects, the lenses of many lens combinations have various aspheric surfaces, even free-form surfaces, and are suitable for molding or injection molding, using mold cores with predetermined free-form surfaces, to measure these optical lenses Produce. In the process of forming the lens by compression molding, it includes a demoulding process, which is to separate the two corresponding mold cores from the finished lens. During this process, the processing traces existing on the free-form surface of the mold core avoid the vacuum phenomenon between the mold core and the surface of the finished lens, so that the demoulding process can be successfully completed. Therefore, for the mold core of this type of optical lens, after the required free-form surface is formed by machining, subsequent polishing or other processing is not required, so the nearly consistent processing traces of the corrugation are sometimes a favorable processing surface.

FIG. 3 is another embodiment of the present invention, a schematic diagram of disposing two mold core materials 10 on an eccentric jig 100 . Similarly, the position of the reference origin O of the eccentric jig 100 falls relative to the axis C, and the mold core material 10 is disposed at an eccentric position away from the reference origin O. The geometric central axis of each mold core material 10 on the way is represented by C". Fig. 4 is another embodiment of the present invention, a schematic diagram of disposing six mold core materials 10 on an eccentric jig 100. The mold core material 10 is placed in an eccentric The positions of the tools 100 may be symmetrical to each other, or may be configured in an asymmetrical manner.

FIG. 5 provides another embodiment of the present invention. In order to increase the efficiency of mass production, multiple auxiliary jigs 120 can be arranged on the eccentric jig 100 to carry more mold core materials 10 . In the example shown in the figure, four mold core materials 10 are respectively arranged on four auxiliary jigs 120. Those skilled in the art can understand that the auxiliary jigs 120 on the eccentric jig 100 may not be limited to four One, and the number of core materials 10 disposed on each auxiliary jig 120 can also be adjusted according to needs, which does not exceed the contemplated scope of the present invention.

Figure 6 shows a sample of mold core material 10 made according to the method of the present invention. The difference in height of the corrugation error in the central area of the mold core is about 5.3 nanometers. Compared with the measurement data shown in Figure 1E, it can be seen that the present invention can effectively improve Problems with traditional slow tool servo machining.

FIG. 7 shows a schematic diagram of surface processing traces of a mold core material 20 sample produced by the method of off-axis ultra-precision machining of free-form surface mold cores according to the present invention. Compared with the spiral or concentric surface processing marks shown in FIG. 1B , no spiral or concentric shapes can be found in the processing trace line pattern shown in FIG. 7 , but approximately parallel lines appear. A closer look at these processing traces reveals that each of these lines has at least two endpoints. For example, tooling line 201 has endpoints 201a and 201b, tooling line 202 has endpoints 202a and 202b, and tooling line 203 has endpoints 203a and 203b. In contrast to the spiral or concentric surface processing marks shown in FIG. 1B , only one end point can be seen near the center. Therefore, it can be understood from the line patterns shown in FIG. 2 and FIG. 7 that the mold core material 10/20 is arranged at an eccentric position during processing. Since the free-form mold core product is processed off-axis according to the embodiment of the present invention, the processing traces on the processed surface usually form similar patterns. Therefore, there is a free-form surface on the mold core, and there are many processing marks on the free-form surface, and there are no concentric processing marks on the free-form surface. Furthermore, the mold core is used to manufacture lenses, so the produced lenses have a free-form surface, and there are many processing marks on the asymmetrical surface, and the processing marks are in the shape of non-concentric circles.

The machining tool of the above-mentioned slow tool servo machining device 1 can be a cutting tool or a grinding wheel, so the slow tool servo machining is an ultra-precision turning process and/or an ultra-precision grinding wheel process. The mold core with a free-form surface manufactured according to the present invention includes a processed free-form surface with a plurality of processing marks, and the free-form surface does not have concentric circle-shaped processing marks.

It can be seen from the above description that in some embodiments, the mold core manufacturing method with a free-form surface can greatly increase the mass production efficiency, and the centrifugal configuration can reduce the depth difference of the free-form surface processing marks (corrugations). Small, it can be said to be technological innovation.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone skilled in this art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be determined by the scope of the attached patent application. In addition, any embodiment or scope of claims of the present invention does not necessarily achieve all the objectives or advantages or features disclosed in the present invention. In addition, the abstract and the title are only used to assist the search of patent documents, and are not used to limit the scope of rights of the present invention.

1: Slow knife servo processing device 2: The first platform 3: Machining the axis of rotation 4: Second platform 5: Processing tool 7: Materials to be processed

10/20: mold core material

100: Eccentric fixture

120: Auxiliary fixture

201/202/203: Processing marks

Acut: Processing path

C: axis

C”: Geometric central axis

O: Reference origin

P1: Measurement starting point

P2: Measurement end point

X: The direction of the first axis

Y: The direction of the second axis

This case can be better understood by the detailed description of the following drawings: Figure 1A is a schematic diagram of a conventional slow-tool servo machining device; Figure 1B is a schematic top view of the cut surface after slow-tool servo machining; Fig. 1C is a schematic diagram of the processing trace line depth of the mold core material in Fig. 1B; Fig. 1D is another schematic diagram of the processing trace line depth of the mold core material in Fig. 1B; Fig. 1E is another schematic diagram of the processing trace line depth of the mold core material in Fig. 1B; A schematic diagram of the depth of the machining traces on the cutting surface; FIG. 2 is a schematic diagram of an embodiment of manufacturing a mold core by off-axis slow-tool servo machining according to the present invention; FIG. 3 is a schematic diagram of disposing the mold core material on Schematic diagram of the eccentric jig; Figure 4 is a schematic diagram of disposing the mold core material on the eccentric jig according to another embodiment of the present invention; Figure 5 is a schematic diagram of disposing the mold core material on the eccentric jig according to another embodiment of the present invention Schematic diagram; FIG. 6 shows a schematic diagram of the depth of processing traces on the cutting surface of a mold core material sample produced according to an embodiment of the present invention; FIG. 7 shows a schematic diagram of the surface processing traces of a sample produced according to an embodiment of the present invention.

10: mold core material

100: Eccentric fixture

Acut: Processing path

C: axis

O: Reference origin

X: The direction of the first axis

Y: The direction of the second axis

Claims (12)

A method for manufacturing a mold core with a free-form surface, comprising the following steps: placing a mold core workpiece on a rotating shaft surface of a processing machine, and the central axis of the mold core workpiece in contact with the rotating shaft surface, and the rotating shaft surface The axis center of the processing machine is not coaxial; rotate the rotation axis surface of the processing machine, and make the rotation axis surface and a processing tool relatively move in three directions of rotation axis and radial direction for processing; continue processing until a The mold core has a free-form surface, and the free-form surface has a plurality of non-concentric processing trace lines. The mold core manufacturing method according to claim 1, wherein the processing machine is one of a cutting knife and a grinding wheel. The mold core manufacturing method as claimed in claim 1, wherein the rotating axis moves in a two-dimensional direction, and the processing tool relatively moves in another one-dimensional direction, and wherein the processing tool is a slow tool servo processing method. A mold core with a free-form surface is produced by the manufacturing method of Claim 1. The mold core includes a machined free-form surface with a plurality of processing traces, and the processing traces are in the shape of non-concentric circles. A mold core includes a free-form surface, the curved surface has a plurality of processing traces, and the processing traces are in the shape of non-concentric circles. A lens manufacturing method, comprising the following steps: heating a lens material; placing the heated lens material between a first mold core and a second mold core; and the first mold core is provided with a free-form surface, and the free The curved surface has a plurality of non-concentric processing trace lines; the lens material is cooled; the lens is released from the first mold core and the second mold core to obtain a molded lens. The lens manufacturing method as described in Claim 6, wherein the first mold core is made by the method described in Claim 1. The lens manufacturing method as described in Claim 6 or Claim 7, wherein the lens material is injected between the first mold core and the second mold core in a high-speed and high-pressure manner, and after cooling and forming, the lens is take out. The lens manufacturing method as claimed in claim 6 or claim 7, wherein the lens material is an optical resin. The lens manufacturing method according to claim 6, wherein when the lens material is placed between the first mold core and the second mold core, a cavity is formed between the first mold core and the second mold core, and The heated lens material is placed in the cavity, filling the cavity. A lens manufactured by the lens manufacturing method described in Claim 6 or Claim 7. A lens with a free-form surface includes a processed surface with a plurality of processing traces, and the processing traces are in the shape of non-concentric circles.

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