JP2016055362A - Electrode for electric discharge processing and electric discharge processing method with use of electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently make a mold for manufacture of a lens array.SOLUTION: There are provided an electrode for electric discharge processing comprising a spherical electric discharge electrode, and a stationery part which so presses the spherical electric discharge electrode by a spring that at least a part of the spherical electric discharge electrode is exposed on a work-piece side and fix the spherical electric discharge electrode; and an electric discharge processing method for a mold for manufacture of a lens array with use of the electrode for electric discharge processing. According to the method, a mold for manufacture of a lens array is made by repeating the following steps: an electrical discharging step of electrically discharging a material of a mold for manufacture of a lens array thereby forming a lens element shape having an arrangement pitch of a natural number of an arrangement pitch of a lens element of a mold for manufacture of a lens array; and a moving step of moving a position at which electric discharging is performed by a length of a natural number of the arrangement pitch of the lens element of a mold for manufacture of a lens array.SELECTED DRAWING: Figure 1-1

Description

  The present invention relates to an electric discharge machining electrode suitable for manufacturing a mold for manufacturing a lens array, an electric discharge machining method using the electrode, and an electric discharge machining apparatus.

  A lens array is an optical element in which a plurality of lenses are integrated. Lens arrays are heavily used in liquid crystal projectors and illumination optical systems for semiconductor exposure apparatuses.

  As one of the mass production methods for lens arrays, a lens array manufacturing mold is manufactured by integrating multiple convex or concave parts that shape the shape of a lens element, and then the lens array material such as plastic or glass is poured into the mold. The technique of manufacturing by doing is used. When the lens array material is poured into the lens array manufacturing mold, the material is melted at a high temperature, and after pouring into the lens array manufacturing mold, a high pressure is applied to shape the lens element shape. Therefore, a material having a sufficient strength at a high temperature and a high pressure is required as a material for the lens array manufacturing mold. For example, in the case of a plastic lens array, an electroless nickel phosphor plating is applied to a steel material. In the case of a glass lens array, cemented carbide or silicon carbide is used as a lens array manufacturing mold material. Used.

Japanese Patent Application No. 2007-949 Japanese Utility Model Publication No. 62-150024

"Proc. 7th International Conference on Leading Edge Manufacturing in 21st Century (LEM21)", Nov. 7-8, 2013, p. 411-414 "Precision Proceedings of the Japan Society for Precision Engineering Autumn Conference", September 13, 2013, p. 985-986

  As a method of manufacturing a lens array manufacturing mold from a steel material that is a material of a lens array manufacturing mold, the surface of the material is cut and polished into a concave mold that shapes the shape of a lens element, and lens elements are manufactured one by one. Then, the method of providing electroless nickel phosphorus plating can be considered. However, steel materials have sufficient strength against cutting and polishing, and it takes time even to produce one lens element. Similarly, when a cemented carbide or silicon carbide is used as a material for a lens array manufacturing mold, it takes time to manufacture a lens element. Therefore, there is a problem that it takes much time to manufacture a lens array manufacturing mold in which a plurality of lens elements are integrated.

  The inventors of the present invention have devised a new method in Non-Patent Documents 1 and 2 in an attempt to improve the method for manufacturing the lens array manufacturing mold described above. That is, as a manufacturing method of a mold for manufacturing a lens array, by electric discharge machining using an electric discharge machining electrode including a single or plural rod-shaped electric discharge electrodes obtained by machining the tip of a round bar used as an electrode surface into a spherical shape by cutting. A method for manufacturing a mold for manufacturing a lens array was proposed. By using electric discharge machining, it became possible to manufacture a lens array manufacturing mold in a shorter time than in the past. Further, by using an electric discharge machining electrode including a plurality of discharge electrodes, a plurality of lens elements can be manufactured once, and a lens array manufacturing mold can be manufactured in a shorter time.

  However, in the method for manufacturing the lens array manufacturing mold described above, when the tip of a round bar used as an electrode surface is processed into a spherical shape by cutting, if the shape accuracy of the spherical surface is low, the lens element of the lens array manufacturing mold As a result, there is a problem that the shape accuracy of the spherical surface of the lens array is lowered, and as a result, the quality of a lens array manufactured using a lens array manufacturing mold is deteriorated. On the other hand, when trying to improve the shape accuracy of the spherical surface of the electrode surface, it takes time to cut the spherical surface, so there is a trade-off between the quality of the lens array manufacturing mold and the manufacturing cost. It was.

  Patent Documents 1 and 2 describe a technique for performing electric discharge machining using a spherical surface of a conductive sphere as an electrode surface. Further, Patent Document 1 describes a method of rotating a sphere and using an unused spherical surface as a new electrode surface when the spherical surface used as the electrode surface is consumed. Although the electrode for electric discharge machining described in these documents can be used for manufacturing a mold for manufacturing a lens array, the conductive sphere is fixed using a magnetic force or a one-touch joint in the document. When the spherical surface that is consumed when rotating is brought into contact with the fixing device for the sphere, the fixing position of the sphere changes.

Patent Document 1 also refers to an electrode for electric discharge machining provided with a plurality of spheres. However, since the specific configuration is unclear, the present inventors based on the techniques disclosed in Patent Documents 1 and 2, the configuration of the electrode for electric discharge machining having a plurality of spheres, and the A method for manufacturing a mold for manufacturing a lens array using electrodes has been intensively studied. As a result, it has been found that it is difficult to manufacture a highly accurate mold for manufacturing a lens array by the techniques described in Patent Documents 1 and 2. The reason is as follows. That is, in Patent Documents 1 and 2, in order to hold a plurality of spheres, it is necessary to use a plurality of electrode bodies having a chip receiver for holding the spheres. However, it is difficult to process a plurality of chip receivers with high accuracy and the same shape, and the positions where the plurality of spheres are held are not aligned unless the chip receivers can be processed with high accuracy and the same shape. As a result, there is a variation in the electrode surface of the work piece as a material and each sphere, and the shape of the processed lens elements is not the same, and as a result, a highly accurate lens array manufacturing mold cannot be manufactured. found.

  That is, the electrode for electric discharge machining described in Patent Documents 1 and 2 is a lens array manufacturing that requires accurate machining of lens elements regardless of whether a single sphere or a plurality of spheres are used. It is not preferable for manufacturing a metal mold.

  In order to solve the problems as described above, the present invention is configured to press and fix the spherical discharge electrode by a spring so that at least a part of the spherical discharge electrode and the spherical discharge electrode are exposed to the workpiece side. An electrode for electric discharge machining comprising a fixing portion to be proposed is proposed.

  Also, there is provided an electric discharge machining method for a lens array manufacturing mold using the above-mentioned electrode for electric discharge machining, wherein the lens element of the lens array manufacturing mold is formed by performing electric discharge machining on the material of the lens array manufacturing mold. An electric discharge machining step for producing a lens element shape having an arrangement pitch that is a natural number multiple of the arrangement pitch, and a movement that moves the position to be subjected to the electric discharge machining by a length that is a natural number multiple of the arrangement pitch of the lens elements of the lens array manufacturing mold. And an electrical discharge machining method for manufacturing a lens array manufacturing mold by repeating the steps.

  In the electrode for electric discharge machining according to the present invention, a spherical body with high shape accuracy of the spherical surface used for the spherical electric discharge electrode can be obtained at low cost. Moreover, it is possible to use the obtained sphere as a sphere discharge electrode as it is, and by performing electric discharge machining using the electric discharge machining electrode, a high-quality lens array production mold is manufactured at low cost. It becomes possible.

  Furthermore, since the discharge electrode made of a sphere is pressed and fixed by a spring, the entire surface of the sphere can be used as an electrode surface by rotating the sphere, and one sphere discharge electrode can be used for a long time. It is. That is, the manufacturing cost of the lens array manufacturing mold can be reduced.

Schematic diagram showing an example of the configuration of an electrode for electrical discharge machining Outline diagram showing an example of the configuration of the fixed part Schematic diagram showing an example of the configuration of an electrode for electrical discharge machining Schematic diagram showing an example of an electrode for electric discharge machining provided with a plurality of spherical discharge electrodes Schematic diagram showing an example of another configuration of the fixed portion Example of functional block diagram of EDM device for mold for lens array manufacturing An example of processing order of lens elements of EDM Another example of processing order of lens elements in electrical discharge machining equipment Another example of processing order of lens elements in electrical discharge machining equipment An example of a method of manufacturing a mold for manufacturing a lens array using an electric discharge machining apparatus Electrode for electric discharge machining used in the examples and its design drawing Blueprint of lens array manufacturing mold manufactured in Example Optical microscope image of lens array manufacturing mold processed in Example Example of the measurement result of the cross-sectional shape of each lens element of the lens array manufacturing mold produced in the example Results of calculating the radius of curvature from the cross-sectional shape of the lens element produced in the example Example of shape error of lens element processed in embodiment Overview of the electric discharge machining method for the lens array manufacturing mold carried out in this embodiment

Embodiments of the present invention will be described below with reference to the drawings. The relationship between the embodiment and the claims is as follows. The first embodiment mainly corresponds to claims 1 to 5. The second embodiment mainly corresponds to claims 6 to 9. In addition, this invention is not limited to description of this specification at all, and can be implemented with various aspects within the range which does not deviate from the summary. Similarly, the present invention is not limited to the drawings.
<< Embodiment 1 >>
<Overview>

This embodiment relates to an electric discharge machining electrode suitable for manufacturing a lens array manufacturing mold.
<Configuration>

FIG. 1-1 is a schematic diagram illustrating an example of the configuration of an electrode for electric discharge machining according to the present embodiment. (A) is a top view, (b) is a bottom view, and (c) is a side view. For example, the electric discharge machining electrode 0101 according to the present invention may be composed of a spherical discharge electrode 0102 and a fixed portion 0103.
<Specific configuration>

  “Spherical discharge electrode” 0102 is a discharge electrode made of a sphere. In order to function as a discharge electrode, a conductive material is used for the sphere. As the spherical material, copper, copper tungsten, and graphite are preferable in consideration of cost, stability, workability, and the like. It is also possible to use a sphere whose surface is covered with a conductor. At least a part of the spherical discharge electrode 0102 is exposed to the workpiece side from the fixing portion 0103, and the exposed surface is an electrode surface of the electrode for electric discharge machining according to the present invention.

  In electric discharge machining, the shape of the electrode surface affects the machining shape of the workpiece. That is, the diameter of the spherical discharge electrode, the so-called radius of curvature of the spherical discharge electrode, and the exposure amount of the electrode surface of the spherical discharge electrode influence the shape of the lens element of the lens array manufacturing mold to be manufactured. Therefore, it is preferable that the sphere used as the sphere discharge electrode has high spherical shape accuracy.

  The sphere used for the sphere discharge electrode 0102 is manufactured as follows when, for example, copper or copper tungsten is used as a material. That is, first, a copper or copper tungsten block to be a sphere is cut into a size about the diameter of the sphere to be produced. Next, the cut material is compression-molded by a press machine and processed into a sphere. Since the shape of the spherical surface is poor as it is in the compressed state, the spherical shape can be manufactured by rough polishing by barrel polishing and lapping the sphere using a lapping apparatus. When graphite is used as a material, first, a graphite block to be a sphere is cut into a size approximately equal to the diameter of the sphere to be manufactured. Next, the cut material is processed into a sphere by grinding. Thereafter, rough polishing is performed by barrel polishing, and the sphere is lapped using a wrapping apparatus, whereby the sphere can be manufactured. In the present embodiment, the manufacturing method of the sphere is not limited to the above-described method, and various methods can be used. A plurality of spheres can be polished and lapped at the same time, and a sphere with high spherical shape accuracy can be obtained at low cost.

  When the electric discharge machining is performed a plurality of times, the electrode surface which is an exposed surface deteriorates, and the shape accuracy of the spherical surface of the electrode surface deteriorates. However, the spherical discharge electrode 0102 can change the electrode surface deteriorated by rotating the sphere to an unused spherical surface that is not deteriorated, and one spherical discharge electrode can be used over a long period of time. The manufacturing cost of the electrode for electric discharge machining can be reduced. Furthermore, since the spherical discharge electrode is fixed by a spring 0107, which will be described later, even when a part of the spherical body deteriorates due to electrical discharge machining and the spherical shape accuracy deteriorates, the spherical body is accurately placed on the spherical discharge electrode mounting plate. The lens element can be manufactured precisely.

  The “fixing portion” 0103 is a member that presses and fixes the spherical discharge electrode with a spring so that at least a part of the spherical discharge electrode 0102 is exposed to the workpiece side. As shown below, the fixing portion 0103 can be fitted with a spherical discharge electrode 0102, and the spherical discharge electrode can be replaced or the electrode surface of the spherical discharge electrode can be changed. As the material of the fixed part, a conductor such as copper or copper tungsten may be used, or an insulator may be used. However, voltage is applied to the spherical discharge electrode through the fixed part. A configuration is preferable. That is, when the fixed part and the electric discharge machining apparatus are connected, a voltage is supplied from the electric discharge machining apparatus to the fixed part, and a voltage is supplied from the fixed part to the spherical discharge electrode. The shape of the fixed portion is not particularly detailed, and can be changed as appropriate according to the specifications of the electrical discharge machining apparatus to be connected.

  The fixing unit 0103 is mainly composed of a spherical discharge electrode mounting plate 0104, a pressing plate 0105, and a spring 0107.

  The “spherical discharge electrode mounting plate” 0104 is provided with a through hole 0106. The “through-hole” 0106 is a through-hole having a diameter smaller than the diameter of the spherical discharge electrode, and is a hole such that a part of the spherical discharge electrode is exposed to the opposite side through the hole. Electric discharge machining is performed using an exposed surface that is a part of the spherical discharge electrode exposed through the through hole as an electrode surface.

  The height of the spherical discharge electrode 0102 exposed from the spherical discharge electrode mounting plate 0104 is preferably set to be equal to or greater than the depth of the concave portion of the lens element of the lens array manufacturing mold to be manufactured. Therefore, it is preferable that the diameter of the spherical discharge electrode, the diameter of the through hole, and the thickness of the spherical discharge electrode mounting plate are determined so as to satisfy the conditions. If the exposed surface of the spherical discharge electrode is configured to be the same as the shape of the lens element of the lens array manufacturing mold to be manufactured, excessive processing and insufficient processing are prevented during electric discharge machining. It is more preferable because the tolerance can be reduced.

  FIG. 1-2 is a diagram illustrating an outline of the through hole 0106 in the fixing portion. It is desirable that the through hole in the fixing portion has a regulation structure in which the side surface of the through hole and the side surface of the pressing device are in contact so that the movement of the pressing device 0108 described later is limited to the extension direction of the spring 0107 described later (a ). However, in the present invention, the regulating structure is not necessarily essential (b), and those skilled in the art have conceived such as a configuration (c) in which the side surface of the through hole is processed into a spherical surface in accordance with the spherical surface of the spherical discharge electrode to be mounted. To the extent possible. In addition, it is possible to process the through-hole (c) processed into the spherical surface by milling using a ball end mill or wire electric discharge machining, for example.

  The “pressing plate” 0105 is for pressing the spherical discharge electrode 0102 against the spherical discharge electrode mounting plate 0104. It is preferable that a spring 0107 and a pressing device 0108 are attached to the pressing plate. When a spring is attached to the pressing plate, it is desirable that the spring can be fixed at a predetermined position of the pressing plate. For example, a configuration in which a conical protrusion 0113 having the same diameter as the inner diameter of the spring is provided at a predetermined position of the pressing plate can be considered.

  The spherical discharge electrode 0102 is preferably configured to be pressed from the pressing plate 0105 to the spherical discharge electrode mounting plate 0104 through a “spring” 0107. For example, when a spherical discharge electrode is simply sandwiched between a spherical discharge electrode mounting plate and a pressing plate and fixed with a screw without using a spring, the spherical discharge electrode may be damaged due to overtightening of the screw. There is a possibility of deforming the spherical shape. By adopting a configuration in which the spherical discharge electrode is pressed using a spring, the spherical discharge electrode can be pressed against the spherical discharge electrode mounting plate with an appropriate force with high accuracy.

  Further, when the electrode surface of the sphere discharge electrode 0102 is changed from a deteriorated spherical surface to an unused spherical surface by rotating the sphere, the spherical shape of a part of the sphere is deteriorated by the electric discharge machining. The spherical discharge electrode can be accurately pressed against the spherical discharge electrode mounting plate 0104 even when the spherical shape changes due to expansion and contraction, and the electrode surface can be accurately reproduced even when the sphere is rotated. Therefore, the entire sphere can be used as the electrode surface. When the sphere is rotated, it is preferable that the deteriorated spherical surface and the sphere discharge electrode mounting plate are not in contact with each other.

  Further, when the spherical discharge electrode 0102 is pressed using the spring 0107, the diameter of the spherical body used as the spherical discharge electrode with respect to the fixed portion can be given a certain width by the expansion and contraction of the spring, and the shape of the electrode surface Can be changed. Further, by adjusting the elastic force of the spring 0107, the exposure amount of the spherical discharge electrode can be changed to change the shape of the electrode surface.

  As the spring 0107, a leaf spring described later can be used in addition to the coil spring. Furthermore, it is good also as a structure which presses the spherical discharge electrode 0102 using an elastic body like rubber instead of a spring, a piston cylinder, etc. FIG.

  The “pressing device” 0108 is a device connected to the spring 0107, transmits the elastic force received from the spring pressed by the pressing plate 0105 to the spherical discharge electrode, and presses the spherical discharge electrode 0102 against the spherical discharge electrode mounting plate 0104. It is an instrument to do. It is preferable that the surface of the pressing device in contact with the spherical discharge electrode is configured to stabilize the center of the spherical discharge electrode on an extension line of the central axis of the pressing device. For example, it is conceivable that the surface of the pressing device that comes into contact with the spherical discharge electrode is recessed so as to form a conical side surface with the central axis of the pressing device as the axis and the bottom surface as the spherical discharge electrode side. In addition, the electrode 0101 for electric discharge machining of this invention can also consider the structure which presses a spherical discharge electrode directly with a spring not including a pressing instrument (FIGS. 1-3).

  The pressing plate 0105 may be configured to be connected to the spherical discharge electrode mounting plate 0104 by “screws” 0109. At that time, the distance between the pressing plate and the spherical discharge electrode mounting plate can be kept constant by connecting the pressing plate and the spherical discharge electrode mounting plate using the “spacer” 0110.

  Further, a “chuck” 0111 may be attached to the pressing plate 0105 in order to connect to the electric discharge machining apparatus. The shape and size of the chuck are appropriately changed according to the electric discharge machining apparatus to be connected. The chuck may be configured to be connected to the pressing plate by “screw” 0112 or may be integrated with the pressing plate. When the voltage is supplied to the spherical discharge electrode 0102 through the chuck, the voltage is supplied from the chuck through the pressing plate, the spring 0107, and the pressing device 0108, or from the chuck to the pressing plate, the screw 0109 or the spacer 0110, It is conceivable that the material is supplied via the spherical discharge electrode mounting plate 0104.

  FIG. 2 is a schematic view showing an example of an electric discharge machining electrode 0101 having a plurality of spherical discharge electrodes 0102. (A) is a top view, (b) is a bottom view, and (c) is a side view. The spherical discharge electrode mounting plate 0104 shown in FIG. 2 is provided with four through holes 0106, so that four spherical discharge electrodes can be attached. By providing a plurality of spherical discharge electrodes, it is possible to perform electric discharge machining at a plurality of positions at the same time, and in a shorter time than using an electric discharge machining electrode having a single spherical discharge electrode, The mold can be manufactured.

  When a plurality of spherical discharge electrodes 0102 are provided in the electric discharge machining electrode 0101, it is preferable that the electrode surfaces that are exposed surfaces from the fixed portions of the respective spheres are the same. In the present invention, since the spherical discharge electrode is fixed by the spring 0107, when the electrode surface deteriorated by the electric discharge machining is changed to an unused spherical surface, the spherical discharge electrode of each spherical discharge electrode depending on the degree of deterioration of the sphere and the rotation amount is used. The change of the fixed position can be prevented and the electrode surfaces can be made the same. The electrode surface of each sphere can be changed depending on the shape of the lens element of the lens array manufacturing mold to be manufactured.

  When the spherical discharge electrode mounting plate 0104 includes a plurality of through holes 0106, the intervals between the through holes are arranged at an arrangement pitch that is a natural number multiple of the arrangement pitch of the lens elements of the lens array manufacturing mold to be manufactured. It is desirable. This is because the distance between the through holes is the same as the arrangement pitch of the lens elements of the lens array manufacturing mold, and the distance between the lens elements is not uniform unless it is a natural number multiple.

  Further, when the spherical discharge electrode mounting plate 0104 is provided with a plurality of through holes 0106 and the electric discharge machining electrode 0101 is provided with a plurality of spherical discharge electrodes 0102, the application of voltage to each spherical discharge electrode can be individually controlled. Such a configuration may be adopted. Then, by applying a voltage only to a part of the spherical discharge electrodes during the electric discharge machining, the electric discharge machining can be performed using only the spherical discharge electrodes to which the voltage is applied. By adopting this configuration, the lens elements of the lens array manufacturing mold to be manufactured can be arranged more freely.

  FIG. 3 is a schematic diagram showing an example of a fixing portion different from the fixing portion described above. In this example, a leaf spring is used to press the spherical discharge electrode. (A) is a top view, (b) is a bottom view, (c) is a side view, and (d) is a perspective view of a spherical discharge electrode placement device. For example, the fixing portion 0301 in this example is mainly composed of a substrate 0302, a spherical discharge electrode placement device 0303, and a leaf spring 0304. By pressing and fixing the spherical discharge electrode using a leaf spring, the spherical discharge electrode can be fixed with high precision, and the same effect as the above-described fixing portion is brought about.

  In the fixing portion 0301 shown in FIG. 3, when the electrode surface of the spherical discharge electrode 0102 is deteriorated, a spherical surface that is not deteriorated by rotating the spherical discharge electrode can be used as a new electrode surface. It is preferable that the surface of the discharge electrode not deteriorate is in contact. The contact between the sphere and the substrate occurs at only one point, and if the spherical surface of the contact point is not deteriorated, the sphere discharge electrode can be fixed as before rotation even if the sphere discharge electrode is rotated. The electrode surface can be reproduced.

  The “plate spring” 0304 may be connected to the substrate 0302, the spherical discharge electrode placement device 0303, and the substrate 0302 by, for example, a screw 0305, and press the spherical discharge electrode 0102. The arrangement of the spherical discharge electrode is determined by a spherical discharge electrode placement device, but it is preferable that the spherical discharge electrode is arranged at a predetermined position even by pressing a leaf spring. For example, the protrusions 0308 having the same length and recessed at the tip of the spherical surface are provided radially at predetermined positions of the leaf spring, and the spherical discharge electrodes are arranged at the center of each protrusion by pressing the spherical discharge electrodes with the protrusions. Can do. The exposed surface of the spherical discharge electrode exposed from the leaf spring is the electrode surface of the electric discharge machining electrode 0101. When the spherical discharge electrode is fixed by the leaf spring, details such as the shape and thickness of the leaf spring are not limited as long as at least a part of the spherical discharge electrode is exposed from the leaf spring as an electrode surface. For example, even if it is the structure which presses a some spherical discharge electrode with one leaf | plate spring, the structure which provides and presses a leaf | plate spring for every spherical discharge electrode may be sufficient.

  A hole 0306 is provided in the “spherical discharge electrode placement device” 0303 (FIG. 3D). “Hole” 0306 is a spherical discharge electrode placed inside the hole, and when connecting the substrate 0302 and the leaf spring 0304 via the spherical discharge electrode placement device, at least a part of the spherical discharge electrode serves as an electrode surface. It is a hole for arranging the spherical discharge electrode at a specific position of the fixing portion 0301 so as to be exposed from the leaf spring. It is desirable that the hole is a through hole that does not cause a gap between the hole and the spherical discharge electrode. By adopting this configuration, the spherical discharge electrode can be accurately positioned at a desired position. The shape of the hole may be a square or the like as long as the spherical discharge electrode can be disposed. The material may be a conductor or an insulator. In this figure, four holes are provided, and four spherical discharge electrodes are provided. However, the number of holes provided in the spherical discharge electrode placement tool depends on the lens array manufacturing mold to be manufactured. It can be changed accordingly.

  In addition, the board | substrate and the spherical discharge electrode arrangement | positioning instrument may be united. In this case, the hole 0306 is not a through hole but a blind hole. In the case of a configuration including a plurality of spherical discharge electrodes 0102, it is desirable that all blind holes have the same depth. It is desirable to make the height of the exposed parts of all the spheres the same by making all the blind holes the same depth.

Note that a “chuck” 0307 may be attached to the substrate 0302 in order to connect to the electric discharge machining apparatus. The shape and size of the chuck are appropriately changed according to the electric discharge machining apparatus to be connected. The chuck may be configured to be connected to the substrate by screws 0305. When the voltage is supplied from the chuck to the sphere discharge electrode, the structure supplied from the chuck through the substrate, the structure supplied from the chuck through the sphere discharge electrode placement device, the chuck from the substrate, Various paths are conceivable, such as a spherical discharge electrode placement device, a configuration supplied via a leaf spring.
<Effect>

By adopting the configuration as described above, it is possible to provide an electrode for electric discharge machining suitable for manufacturing a lens array manufacturing mold with good shape accuracy of the spherical surface of the electrode surface and low manufacturing cost.
<< Embodiment 2 >>
<Overview>

The present embodiment relates to an electric discharge machining method and an electric discharge machining apparatus for a lens array manufacturing mold using an electrode for electric discharge machining suitable for manufacturing the mold for manufacturing a lens array shown in the first embodiment.
<Configuration>

FIG. 4 shows an example of functional blocks of the electric discharge machining apparatus for the lens array manufacturing mold shown in the present embodiment. For example, it is considered that the electric discharge machining apparatus 0401 shown in the present embodiment includes an electric discharge machining unit 0402, a moving unit 0403, a workpiece fixing unit 0404, a high voltage generation unit 0405, and a control unit 0406. It is done.
<Specific configuration>

  “Electrical discharge machining unit” 0402 is a lens having an arrangement pitch that is a natural number multiple of the arrangement pitch of lens elements of a lens array manufacturing mold to be manufactured later by performing electric discharge processing on the lens array manufacturing mold material. It has a function of producing element shapes. The electric discharge machining portion includes the electric discharge machining electrode 0101 described in the first embodiment. The number of lens element shapes to be manufactured depends on the number of spherical discharge electrodes installed on the electric discharge machining electrode used for the electric discharge machining electrode.

  The “moving unit” 0403 has a function of moving the position where the electric discharge machining unit 0402 performs electric discharge machining by a length that is a natural number times the arrangement pitch of the lens elements of the lens array manufacturing mold. The movement may be controlled by a control unit 0406 described later.

  FIG. 5A shows an example of the processing sequence of the lens element 0501 of the electric discharge machining apparatus 0401 when the electric discharge machining electrode 0101 having one spherical discharge electrode 0102 is used. The electric discharge machining unit performs electric discharge machining at the position of each number, and when machining is completed, the moving unit 0403 moves the object 0502 fixed to the electric discharge machining electrode 0101 or the workpiece fixing unit 0404 to the next numbered position. The electric discharge machining step is performed again at that position. Each lens element may be processed at a constant arrangement pitch 0503, but the arrangement pitch can be appropriately determined according to the lens array manufacturing mold to be manufactured.

  FIG. 5-2 shows an example of the processing order of the lens element 0501 of the electric discharge machining apparatus 0401 when the electric discharge machining electrode 0101 having four spherical discharge electrodes 0102 is used. In this figure, the four spherical discharge electrodes are installed at an arrangement pitch that is twice the arrangement pitch of the lens elements of the lens array manufacturing mold. Also in this example, electric discharge machining is performed in the order of the numbers shown in the figure. Compared to the case of FIG. 6, since the number of discharge electrodes is four times, a desired lens array manufacturing mold can be manufactured four times faster.

  FIG. 5C shows another example of the processing order of the lens element 0501 of the electric discharge machining apparatus 0401 when the electric discharge machining electrode 0101 having four spherical discharge electrodes 0102 is used. In FIG. 5-3, the production of 25 lens elements is scheduled. In this case, at the time of the third electric discharge machining, the spherical electric discharge electrode already exists at the position where the lens element machining has already been completed at the first electric discharge machining. In that case, there is generally no problem even if a voltage is applied to the spherical discharge electrode at the already processed position. However, it is also conceivable that machining waste exists between the machined position and the spherical discharge electrode and hinders machining. In this case, this problem can be avoided by cutting off the application of voltage to the spherical discharge electrode existing at the position where the machining is completed. Similarly, in the sixth electric discharge machining and the seventh to ninth electric discharge machining, it is not possible to apply a voltage to the spherical discharge electrode at the position where the lens element machining is completed.

  In the case of electric discharge machining, the distance between the workpiece 0502 and the electric discharge machining electrode 0101 is also important. Therefore, it is desirable that the moving unit 0403 also has a function of moving the electric discharge machining electrode to an appropriate distance from the workpiece. For example, when processing a lens element, the workpiece is gradually processed into a concave shape, but it has a function to keep the distance between the workpiece and the electrode for electric discharge machining constant during electric discharge machining. Can be considered.

  The “workpiece fixing portion” 0404 has a function of fixing the workpiece 0502 that is a material of the lens array manufacturing mold.

  The “high voltage generating unit” 0405 has a function of generating electric discharge by applying a high voltage between the electric discharge machining unit 0402 and the workpiece fixing unit 0404. It is conceivable that the generation of the high voltage is controlled by the control unit 0406.

The “control unit” 0406 has a function of giving an instruction to each functional unit in order to implement the electric discharge machining method of the present embodiment. It is conceivable that the arrangement pitch 0503 of the lens elements of the lens array manufacturing mold to be manufactured is input to the control unit.
<Process flow>

  FIG. 6 shows an example of an electric discharge machining method for a lens array manufacturing mold by the lens array manufacturing mold electric discharge machining apparatus of the present embodiment. First, in the electric discharge machining step, the electric discharge machining electrode is disposed at the electric discharge machining position. Next, a high voltage is applied between the electrode for electric discharge machining and the work piece, and the material for the lens array production mold is subjected to electric discharge machining, so that a natural number of arrangement pitches of the lens elements of the lens array production mold is obtained. A lens element shape having a double arrangement pitch is produced (S0601). When the processing of the lens elements is completed, the position to be subjected to electric discharge machining is moved by a natural number times the arrangement pitch of the lens array of the lens array manufacturing mold (S0602), and the lens array manufacturing mold is moved to the moved position. The material is subjected to an electric discharge machining step. By repeatedly performing S0601 and S0602 until processing of all lens elements is completed, a desired lens array manufacturing mold can be manufactured.

  It is conceivable that the shape accuracy of the surface of the electrode surface in the electric discharge machining electrode deteriorates due to the electric discharge machining a plurality of times, and usually the entire electric discharge machining electrode needs to be replaced at that time, but the spherical electric discharge electrode in the present invention In this case, the surface used as the electrode surface by rotation can be easily changed within the same spherical discharge electrode, and the entire spherical surface can be used as the electrode surface, which is efficient.

When the deterioration of the electrode surface of the spherical discharge electrode 0102 is confirmed, electric discharge machining is performed by rotating the spherical discharge electrode so that the deteriorated electrode surface does not become a newly used electrode surface. The spherical discharge electrode can be used as long as a spherical surface that is not deteriorated by rotation can be used as an electrode surface, and can be replaced with a new sphere when the entire spherical surface deteriorates. The spherical discharge electrode in the present invention is fixed by a spring, and the spherical discharge electrode can be rotated by hand by pressing the spring even when the spherical discharge electrode is mounted on the fixed portion. In order to prevent the spherical discharge electrode from deteriorating, it is also possible to provide a mechanism for constantly rotating the spherical discharge electrode during electric discharge machining so that the surface used as the electrode surface is always changed.
<Effect>

  By adopting the above-described configuration, it is possible to efficiently manufacture a lens array manufacturing mold.

  In this example, the result of manufacturing a lens array manufacturing mold using the electric discharge machining method of the lens array manufacturing mold described in Embodiment 2 is shown. The contents described in this embodiment do not limit the present invention.

  FIG. 13 shows an outline of the electric discharge machining method for the lens array manufacturing mold performed in this embodiment. The workpiece 0502 was installed in the processing oil 1302 on the stage 1301, the electric discharge machining electrode 0101 was brought close to the workpiece, and electric discharge machining was performed at an appropriate position of the workpiece to produce a lens element.

  FIG. 7 shows an outline of the electric discharge machining electrode 0101 used in this example. (A) is the perspective view which image | photographed the electrode for electrical discharge machining, (b) is a design drawing of a side surface. In this example, an electrode for electric discharge machining using one spherical discharge electrode 0102 was used. The diameter of the sphere of the spherical discharge electrode was 4 mm, and the diameter of the through hole provided in the spherical discharge electrode mounting plate was 3.8 mm. The material of the sphere was oxygen-free copper. The electric discharge machining electrode was attached to an electric discharge machining apparatus (EA-12E, manufactured by Mitsubishi Electric Corporation), and electric discharge machining was performed.

  FIG. 8 shows a top view of a lens array manufacturing mold designed in this embodiment. The arrangement pitch of the lens elements 0501 is 0.9 mm, the processing depth of the lens elements is 0.5 mm, and the design radius of curvature (R) of the lens elements is 2.3 mm. processed. The numbers given to the lens elements are the processing order of the lens elements in the electric discharge machining. As a material for the lens array manufacturing mold, a steel material having sufficient strength at high temperature and high pressure was used. Moreover, both surfaces of the steel material to be used were subjected to grinding finish so as not to affect the electric discharge machining, and those having high surface flatness were used.

  The steel material was adjusted so that the flatness of the processed surface of the steel material was ± 5 μm or less with respect to 50 mm. When this mounting accuracy is used, the error due to the installation of the workpiece in the processing depth direction with respect to the processing region of each lens element designed in the present embodiment is ± 0.3 μm or less.

  When performing electrical discharge machining on the steel material for the first time, first, the discharge electrode and the steel material were contact-detected at the processing start point of the first lens element, and this detected position was set as the origin in the depth direction of the processed surface. Thereafter, each lens element was subjected to electric discharge machining to process the lens element. When the processing of each lens element was completed, the electric discharge machining electrode was moved to the next element position to perform electric discharge machining, and electric discharge machining was performed up to 16 elements. The processing order was performed in the order of numbers shown in FIG.

  The result of having observed the processed lens array manufacturing metal mold | die with the optical microscope in FIG. 9 is shown. The concave portion is each lens element 0501, and it can be confirmed that 16 lens elements are produced.

  Next, the cross-sectional shape of each lens element of the produced lens array manufacturing mold was measured using a laser probe non-contact three-dimensional measuring device (manufactured by Mitaka Kogyo, NH-3). The resolution of this measuring instrument is 0.1 μm in the in-plane direction of the processed surface and 0.05 μm in the direction perpendicular to the processed surface. As an example of the measurement result, FIG. 10 shows a cross-sectional shape between AA ′ in FIG.

  FIG. 11 shows the result of obtaining the radius of curvature from the cross-sectional shape of the manufactured lens element 0501 using the least square method. The curvature radius was calculated as an average value of measurement results in two directions perpendicular to each other. As a result of processing 16 lens elements, it was found that the average radius of curvature was between 2.2 mm and 2.4 mm, and it was possible to manufacture a lens array manufacturing mold having lens elements as designed. The standard deviation of the radius of curvature of each lens element was 57 μm.

  FIG. 12 shows an example of the shape error of the processed lens element 0501. The shape error is obtained by subtracting the designed lens element shape from the processed lens element shape. The horizontal axis in FIG. 12 indicates the distance from the tip of the spherical shape, and the vertical axis indicates the error from the design value of the spherical shape. This figure is the result of the 16th lens element processed. This shape error is about 10 μm, and it can be seen that high-precision machining was possible. This error was the same in other lens elements.

0101: Electrode for electric discharge machining 0102: Spherical discharge electrode 0103: Fixed part 0104: Spherical discharge electrode mounting plate 0105: Press plate 0106: Through hole 0107: Spring 0108: Press instrument 0109: Screw 0110: Spacer 0111: Chuck 0112: Screw 0113: Protrusion 0301: Fixing portion 0302: Substrate 0303: Spherical discharge electrode placement device 0304: Leaf spring 0305: Screw 0306: Hole 0307: Protrusion 0401: Electric discharge machining device 0402: Electric discharge machining portion 0403: Moving portion 0404: Fixing workpiece Unit 0405: high voltage generation unit 0406: control unit 0501: lens element 0502: work piece 0503: arrangement pitch S0601: electric discharge machining step S0602: moving step 1301: stage 1302: processing oil

Claims (9)

A spherical discharge electrode comprising a sphere,
A fixing portion that presses and fixes the spherical discharge electrode with a spring so that at least a part of the spherical discharge electrode is exposed to the workpiece side;
An electrode for electric discharge machining.   The electrode for electric discharge machining according to claim 1, wherein the voltage is applied to the spherical discharge electrode through the fixed portion.   The electric discharge machining electrode according to claim 1, comprising a plurality of the spherical discharge electrodes.   The electrode for electrical discharge machining according to any one of claims 1 to 3, wherein the spherical discharge electrode is one of a copper sphere, a copper tungsten sphere, and a graphite sphere.   The plurality of spherical discharge electrodes are arranged at an arrangement pitch that is a natural number multiple of the arrangement pitch of lens elements of a lens array manufacturing mold that is planned to be produced by electric discharge machining using the spherical discharge electrodes. Or the electrode for electrical discharge machining of Claim 4 which depends on Claim 3.   An electric discharge machining apparatus comprising the electric discharge machining electrode according to claim 1. An electric discharge machining method for a mold for manufacturing a lens array using the electric discharge machining electrode according to any one of claims 1 to 5,
An electric discharge machining step for producing a lens element shape having an arrangement pitch that is a natural number multiple of the arrangement pitch of lens elements of the lens array production mold by subjecting the lens array production mold material to electric discharge machining;
A moving step of moving the position to be subjected to electric discharge machining by a length that is a natural number times the arrangement pitch of the lens elements of the lens array manufacturing mold;
An electric discharge machining method for producing a mold for producing a lens array by repeating the above.   A mold for manufacturing a lens array manufactured using the electric discharge machining method according to claim 7.   A lens array manufactured using the lens array manufacturing mold according to claim 8.