TW202228982A - 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

Manufacturing mold core with free-form surface, and method and lens using the mold core to make lenses

The present invention relates to a mold core with a free-form surface and a manufacturing method thereof, and a method for manufacturing a lens by using the mold core, especially a mold core manufactured by off-axis slow-tool servo machining and a method for manufacturing a lens using the mold core.

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

Please refer to FIG. 1A , which shows an example of the 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 machining rotary shaft surface 3, and the machining rotary shaft surface 3 has an axis C, a first axis direction X and a second axis direction Y, and the machining rotary shaft surface 3 is controlled by the first bed 2 to move toward the axis. Move in X or Y direction. The machining tool 5 can be arranged on a 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 to be machined 7 is disposed at a position where the machining rotary shaft surface 3 is adjacent to the axis C, and is machined through an automatic machining program controlled by a computer.

FIG. 1B shows the top view of the cutting surface processed by the slow-tool servo machining device 1 with the mold core material 10 installed on the axis C of the machining rotary shaft surface 3 in a conventional manner, and the reference origin of the intersection of the X and Y axes in the figure O is usually the starting point of machining, and the machining traces formed by the machining path Acut are spread over the cutting surface in an incremental pattern from the reference origin O according to the preset machining path.

1C shows a schematic diagram of a type of machining trace depth D along the X axis of the mold core material 10 in FIG. 1B . C in the figure represents the reference origin O position relative to the axis C of the machining rotational axis surface 3 . As shown in the figure, near the reference origin O, for example, the depth of 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 very different. 1D shows a schematic diagram of another embodiment of the machining trace depth D along the X-axis of the mold core material 10 in FIG. 1B , which is opposite to the pattern in FIG. 1C , the machining between points a' and b' in the figure The trace depth is particularly shallow, but the machining trace depths outside points a and b are also not very different.

Using the mold core made by the above method, because the processing traces appearing near the axis C of the processing rotating shaft surface often have a significant difference in depth with the processing traces in the peripheral parts, so the optical effect of the produced lens is obvious. adversely affected. Therefore, how to avoid the shortcomings of the above devices is a technical problem to be solved. As shown in FIG. 1E , the height difference of the machining traces in the central area of the mold core curved surface after traditional slow tool servo machining is about 18 nm.

According to one aspect of the present invention, a mold core and a manufacturing method thereof manufactured by off-axis slow-tool servo machining are provided, which can generate multiple mold cores with free-form surfaces at one time, thereby improving production efficiency; Consistently, 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 provided. The method includes the following steps: placing a mold core workpiece on a rotating shaft surface of a processing machine, and the mold core workpiece is connected to 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 shaft surface of the processing machine, and make the rotating shaft surface and the processing tool move relative to each other in three dimensions, such as the rotating axial direction, the radial direction, or the rotation of each axis, and perform processing. Continue to process until a mold core with free-form surface is produced.

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

According to another embodiment of the present invention, a method for manufacturing a lens using the mold core made by the above method and a lens manufactured by the method are provided, comprising the following steps: heating a lens material, and then placing the heated lens material in a between a first mold kernel and a second mold kernel. The first mold core is provided with a free-form surface, and the free-form surface has a plurality of machining marks in the shape of non-concentric circles. The lens material is then cooled and shaped. And after the lens is molded, the lens is demolded 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 from the mold core manufactured by the above method.

The method for ultra-precision machining of free-form surface mold cores in an off-axis manner proposed by the present invention is suitable for use in 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 accordingly. However, the implementation of this case is not limited by the following examples. Those with ordinary knowledge in the technical field can still deduce other implementations according to the spirit of the embodiments disclosed in the specification, and these implementations still belong to the scope of the present invention.

The optical lens molding technology uses the continuous and reversible thermal processing properties of the glass from the molten state to the solid state. The glass and the mold are heated and pressurized near the transition temperature Tg of the glass, and the mold core can be used 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 directly molded at one time, which greatly saves materials, time, equipment and manpower, and can mold different shapes, especially In the manufacture of aspherical optical glass parts. In addition to glass materials, this method can also be used to make lenses of other materials. Said lens material is, for example, glass glass. According to an embodiment, when using the mold core to manufacture a lens, the lens material can 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 body, and the heated lens material is placed in the cavity to fill the cavity. In the case of injection molding, the lens material is usually injected between two molds at 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 processing marks in the shape of non-concentric circles, after cooling the lens material, the lens is demolded from the first mold core and the second mold core , then a formed lens with a plurality of non-concentric circle-shaped processing marks on the 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 can combine optical surfaces with mounting features on a cost-effective basis. The precision of injection molding depends on the precision of the machined surface of the mold core, especially the mold core used for the injection molding of optical lenses.

Usually, the movable side and the fixed side of the injection molding die set respectively include a structure with substantially the same structure, and the runner structure is a corresponding component set, but in another embodiment, it can be selectively embedded in the movable side template, Or it can be used in the fixed side formwork, and the present invention is not limited to this. The injection-molded lens material is, for example, an optical resin. In addition, the hole at the center of the element group on the movable side can be used for accommodating mechanisms such as thimbles. The fixed side mold includes a fixed side template, a fixed side fixed plate (such as a first template), a fixed side pressing template, a fixed side mold core and a filling nozzle. The fixed side fixed plate is provided with an injection port to accept the injection of high temperature flowing plastic. The fixed side template has a flow channel to provide a flow channel for high temperature flowing plastic. The fixed side mold core has several mold cavities to accommodate high temperature flowing plastic. The mold cavity has a specific shape, such as a polygonal, circular or elliptical cavity, so that the high temperature flowing plastic in the mold cavity is cooled and solidified to form the specific shape, and finally the lens is removed from the first mold core and the second mold. The kernel 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 having a free-form surface according to the present invention. With reference to FIG. 3 , the present invention provides an eccentric fixture 100 on which at least one mold core material 10 can be arranged, and the geometric center axis of each mold core material 10 is represented by C". When the eccentric fixture 100 is installed As shown in FIG. 1A for the machining of the rotary axis surface 3 on the slow-tool servo machining device 1, it can be seen from the figure that the axis C of the machining rotary axis surface 3 and the geometric center axis C″ of each mold core material 10 are not coaxial, and Since each mold core material 10 is not located at the position of the axis C of the machining rotary shaft surface 3, it is said to be arranged eccentrically.

The position of the reference origin O of the eccentric jig 100 is located relative to the axis C. 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. At the same time, a two-dimensional machining path can be realized along the first axis direction X and the axis 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 surface 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 thereon are grasped in advance, or the three-dimensional geometric relationship between the jig and the workpiece to be processed, in the off-axis machining program control of the present invention Next, the desired free-form surface can be formed on a plurality of 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 using a grinding wheel or the like.

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 rotating axial direction and the radial direction; it is not limited to The rotation axis plane 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, the rotation axis may move in two-dimensional direction, while the machining tool may move in one-dimensional direction, and the two constitute relative three-dimensional movement.

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

Before the actual processing, it is necessary to use fasteners such as positioning pins or screws to dispose the mold core material 10 on the eccentric fixture 100 away from the relative position of the axis C, which keeps the mold core material away from the processing rotation axis surface 3, in other words , the position of the mold core material 10 must be far away from the position of the reference origin O. The example of FIG. 2 shows that four core materials 10 are eccentrically arranged on the eccentric jig 100 , and the number of core materials in practice is not limited to this. It can be understood from the figure that the mold core materials 10 each have its central axis (not shown), and the central axes of the mold core materials 10 and the axis C of the machining rotation axis surface 3 are not coaxial, and the mold core materials 10 are not The position of the axis C of the rotary shaft surface 3 is processed.

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

In order to achieve special optical effects, the lenses of many lens combinations have various aspheric surfaces and even free-form surfaces, which are suitable for molding or injection molding, using mold cores with predetermined free-form surfaces to obtain these optical lenses. Produce. In the process of forming the lens by molding, a demoulding process is included, which is to separate the two corresponding mold cores from the finished lens that is extruded. In this process, the machining 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 demolding process can be completed smoothly. Therefore, for the mold core of this type of optical lens, after machining to form the desired free-form surface, subsequent polishing or other processing is not required, so the nearly uniform processing line of the corrugation is sometimes a favorable processing surface.

FIG. 3 is a schematic diagram of disposing two mold core materials 10 on the eccentric jig 100 according to another embodiment of the present invention. Similarly, the position of the reference origin O of the eccentric jig 100 is located at a position relative to the axis C, and the mold core material 10 is arranged at an eccentric position away from the reference origin O. On the way, the geometric center axis of each mold core material 10 is represented by C". Figure 4 is a schematic diagram of another embodiment of the present invention, where six mold core materials 10 are arranged on the eccentric fixture 100. The mold core materials 10 are placed in the eccentric fixture The positions of the tools 100 may be symmetrical to each other, or may be configured in an asymmetric manner.

FIG. 5 provides another embodiment of the present invention. In order to increase the efficiency of mass production, the eccentric jig 100 can be equipped with a plurality of auxiliary jigs 120 to carry more mold core materials 10 . In the example shown in the figure, four mold core materials 10 are respectively arranged on the four auxiliary jigs 120. Those with ordinary knowledge in the art can understand that the auxiliary jigs 120 on the eccentric jig 100 may not be limited to four. The number of mold core materials 10 disposed on each auxiliary jig 120 can also be adjusted as required, which does not exceed the scope of the present invention.

FIG. 6 shows a sample of the mold core material 10 produced according to the method of the present invention. The difference between the corrugation errors in the central area of the mold core is about 5.3 nm. Compared with the measurement data shown in FIG. 1E , the present invention can effectively improve the Problems with traditional slow tool servo machining.

7 shows a schematic diagram of the surface machining traces of a mold core material 20 produced by the method for ultra-precision machining of free-form surface mold cores in an off-axis manner according to the present invention. Compared with the spiral or concentric surface machining traces shown in FIG. 1B , the machining trace pattern shown in FIG. 7 cannot find any shape similar to a spiral or a concentric circle, but appears like a parallel line. A closer look at these machining traces reveals that each of these lines has at least two endpoints. For example, machining trace 201 has end points 201a and 201b, machining trace 202 has end points 202a and 202b, and machining trace 203 has end points 203a and 203b. In contrast to the spiral or concentric surface machining traces shown in Figure 1B, only one end point is 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 the processing. Since the finished mold core with a free-form surface is processed in an off-axis manner according to the embodiment of the present invention, the processing traces on the processing surface usually form similar patterns. Therefore, there is a free-form surface on the mold core, and there are a plurality of machining traces on the free-form surface, and the free-form surface has no machining traces in the shape of concentric circles. Then, a lens is manufactured by using the mold core, so the lens produced has a free-form surface, and there are a plurality of machining marks on the asymmetrical curved surface, and the machining marks are in the shape of non-concentric circles.

The machining tool of the above-mentioned slow tool servo machining device 1 may be a cutting tool or a grinding wheel, so the slow tool servo machining is an ultra-precision turning machining and/or an ultra-precision grinding wheel machining. The mold core with a free-form surface manufactured according to the present invention includes a processed free-form surface with a plurality of machining traces, and the free-form surface has no machining traces in the shape of concentric circles.

It can be seen from the above description that in some embodiments, the manufacturing method of the mold core with a free-form surface can be greatly increased in terms of mass production efficiency, and the centrifugal configuration can reduce the depth difference of the machining trace (corrugation) of the free-form surface. Small, 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 the 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 appended patent application. In addition, any embodiment of the present invention or the scope of the claims is not required to achieve all of the objects or advantages or features disclosed herein. In addition, the abstract section and the title are only used to aid the search of patent documents and are not intended to limit the scope of the present invention.

1: Slow tool servo processing device 2: The first bed 3: Machining the axis of rotation 4: The second bed 5: Machining tools 7: Materials to be processed 10/20: Mold kernel material 100: Eccentric fixture 120: Auxiliary fixture 120 201/202/203: Machining traces Acut: machining path C: axis C'': geometric center 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: Fig. 1A is a schematic diagram of a conventional slow-tool servo machining device; Fig. 1B is a schematic top view of the cutting surface after slow-tool servo machining; Fig. 1C is a schematic diagram of the machining trace depth of the mold core material in Fig. 1B; Fig. 1D is another schematic diagram of the machining trace depth of the mold core material in Fig. 1B; Fig. 1E is another schematic diagram after slow knife servo machining Figure 2 is a schematic diagram of one embodiment of manufacturing a mold core by off-axis slow-knife servo machining according to the present invention; Figure 3 is another embodiment of the present invention, the mold core material is arranged in A schematic diagram of an eccentric fixture; FIG. 4 is a schematic diagram of disposing a mold core material on an eccentric fixture according to another embodiment of the present invention; FIG. 5 is a schematic diagram of disposing a mold core material on an eccentric fixture according to another embodiment of the present invention Schematic diagram; Figure 6 shows a schematic diagram of the depth of machining traces on the cutting surface of a mold core material sample produced according to an embodiment of the present invention; Figure 7 shows a schematic diagram of surface machining traces of a sample produced according to an embodiment of the present invention.

10: Mold core material

100: Eccentric fixture

Acut: machining 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: A mold core workpiece is placed on the rotating shaft surface of a processing machine, and the central axis of the contact surface between the mold core workpiece and the rotating shaft surface is not coaxial with the axis of the rotating shaft surface; Rotate the rotating shaft surface of the processing machine, and make the rotating shaft surface and the processing tool move relative to each other in three directions such as the rotating axial direction and the radial direction for processing; continue processing until a mold with a free-form surface is produced. Benevolence. The mold core manufacturing method according to claim 1, wherein the processing machine is one of a cutting blade and a grinding wheel. The mold core manufacturing method as claimed in claim 1, wherein the rotational axis plane 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 comprises a processed free-form surface with a plurality of machining traces, and the free-form surface has no concentric machining traces. A mold core includes a free-form curved surface, the curved surface has a plurality of machining traces, and the curved surface has no machining traces in the shape of concentric circles. A method of manufacturing a lens, comprising the following steps: heating a lens material; The heated lens material is placed 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-form surface has a plurality of processing marks in the shape of non-concentric circles; cooling the lens material; The lens is demolded from the first mold core and the second mold core to obtain a molded lens. The lens manufacturing method of claim 6 , wherein the first mold core is manufactured by the method of claim 4 . The lens manufacturing method as claimed in claim 6 or claim 7, wherein the lens material is injected between the first mold core and the second mold core by means of high speed and high pressure, 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 of 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 a cavity is formed between the first mold core and the second mold core. The heated lens material is placed in the chamber, filling the chamber. A lens manufactured by the lens manufacturing method of claim 6 or claim 7. A lens with a free-form surface includes a processed surface with a plurality of processing traces, and the processed surface does not have processing traces in the shape of concentric circles.

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