End mill, method for manufacturing mold for manufacturing microlens, and device for manufacturing mold for manufacturing microlens

Abstract

Provided is an end mill having a cutting edge section having a convex shape having one curved surface obtained by dividing a tapered body by a plane, the tapered body having a tip section and a circular bottom surface, the tip of the tip section being located on a center line penetrating through the center of the bottom surface, the tapered body having a circumferential side surface, and the circumferential side surface being located on the circumferential side surface. The circumferential side surface includes an expanded-diameter region having a larger diameter than the bottom surface, and the plane includes the centerline.

Description

Technical Field

[0001] The present invention relates to an end mill, a method for manufacturing a mold for manufacturing a microlens, and a device for manufacturing the mold for manufacturing a microlens. Background Art

[0002] Conventionally, there is a known method of forming microlenses by using an R-shaped tool to scan along an R-shaped trajectory when forming a microlens master by mechanical processing (see Figure 1A to Figure 1C The above-mentioned tool is provided with a "clearance" in such a way that the part other than the cutting edge does not contact the workpiece during cutting, such as Figure 2 As shown, there is a manufacturing limitation on the angle of the clearance (relief angle). That is, during cutting, cutting can only be performed at an incident angle at which the "relief" of the tool does not contact the workpiece, so it is difficult to perform cutting of deeper microlenses (deep groove processing).

[0003] Therefore, as a method for processing a microlens capable of deep groove processing, cutting processing using a ball-end end mill with a spherical tip shape can be cited. Figure 3 As shown, by performing cutting while rotating the ball end mill at high speed, it is possible to perform cutting of a relatively deep microlens. As such a ball end mill, for example, FIG. 1 of Patent Document 1 proposes a nose end mill with a rounded shape.

[0004] <Prior Art Literature>

[0005] <Patent Documents>

[0006] Patent Document 1: Japanese Patent Application No. 2013-511394 Summary of the invention

[0007] <Problems to be Solved by the Invention>

[0008] However, the conventional ball end mill has a problem that machining defects (cutting marks) occur due to interference between the rotation center of the end mill and the machined surface (see Figure 4 ). Therefore, as a method to prevent machining defects from occurring on the machined surface, it is conceivable to perform cutting by tilting the rotation axis of the cutting edge of the end mill relative to the workpiece, thereby avoiding interference between the machined surface and the rotation center of the end mill (refer to Figure 5A and Figure 5B However, since the cutting edge of the end mill has a range in which it functions as a cutting edge, namely, an effective edge range (Window Angle: WA), if the rotation axis of the cutting edge of the end mill is tilted, there is a problem that the cutting depth becomes shallower than that of horizontal cutting or vertical cutting (see Fig. 6A and Figure 6B ).

[0009] In addition, since the round-shaped nose end mill has a plurality of cutting blades with two or more blades, there is a problem that the diameter of the cutting blade becomes large and it is not suitable for cutting micro lenses with an outer diameter of 100 μm or less.

[0010] The present invention aims to solve the above-mentioned problems in the prior art and achieve the following objectives. That is, the present invention aims to provide an end mill capable of cutting a deeper microlens without causing processing defects caused by the rotation center of the end mill, a method for manufacturing a mold for manufacturing a microlens using the end mill, and a manufacturing device for manufacturing a mold for manufacturing a microlens having the end mill.

[0011] <Methods used to solve the problem>

[0012] In order to solve the above-mentioned problems, one embodiment of the present invention provides an end mill, characterized in that the end mill has a cutting edge portion in the shape of a convex portion, the convex portion shape has a curved surface obtained by dividing a cone with a plane, the cone has a tip portion and a circular bottom surface, the tip of the tip portion is located on a center line passing through the center of the bottom surface, the cone has a circumferential side surface, the circumferential side surface includes an expanded diameter area, the expanded diameter area has a diameter larger than the bottom surface, and the plane includes the center line.

[0013] <Effects of the Invention>

[0014] According to the present invention, there can be provided an end mill capable of cutting deeper microlenses without causing processing defects caused by the rotation center of the end mill, a method for manufacturing a mold for manufacturing a microlens using the end mill, and a manufacturing device for manufacturing a mold for manufacturing a microlens having the end mill. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1A This is a schematic diagram showing an example of an R-shaped cutter.

[0016] Figure 1B This is a diagram for explaining a method of forming a microlens by scanning an R-shaped tool along an R-shaped trajectory.

[0017] Figure 1C This is a schematic diagram showing a microlens formed by scanning an R-shaped tool along an R-shaped trajectory.

[0018] Figure 2 This is a diagram for explaining that during cutting, cutting can only be performed at an incident angle where the “relief” of the tool does not contact the workpiece, so it is difficult to perform cutting processing of a deep microlens.

[0019] Figure 3This is a diagram for explaining a method of cutting a deep microlens using a ball end mill.

[0020] Figure 4 This is a diagram showing a situation in which machining defects occur due to interference between the rotation center of the end mill and the machined surface when cutting is performed using a ball end mill.

[0021] Figure 5A This is a diagram showing a state where a workpiece is cut using a ball end mill.

[0022] Figure 5B This is a diagram for explaining a method of performing cutting processing by tilting the rotation axis of a ball end mill relative to a workpiece.

[0023] Fig. 6A This is a schematic diagram showing an example of a cutting blade portion of a conventional ball end mill.

[0024] Figure 6B It means that Fig. 6A FIG. 1 is a diagram showing a situation in which the cutting depth becomes shallower when the rotation axis of the cutting edge portion of a conventional ball end mill is inclined compared to horizontal cutting or vertical cutting.

[0025] Figure 7 This is a schematic diagram showing an example of the end mill of the present invention.

[0026] Fig. 8A It is a figure which shows the tapered body for forming the cutting edge part of the end mill of this invention.

[0027] Figure 8B This is a diagram showing a semi-conical body formed by dividing a conical body into two, which constitutes the cutting edge portion of the end mill of the present invention.

[0028] Figure 8C This is a diagram showing a tapered body for forming the cutting edge portion of the end mill of the present invention divided into two equal parts.

[0029] Fig. 9A This is a schematic diagram showing another example of the cutting edge portion of the end mill of the present invention.

[0030] Fig. 9B This is a schematic diagram showing a state in which a microlens is cut using the end mill of the present invention.

[0031] Fig. 10A The CAD drawing of the cutting edge portion of the end mill of Comparative Example 1 is shown.

[0032] Fig. 10B This is a diagram showing a microlens produced using the end mill of Comparative Example 1.

[0033] Fig.11AThis is a CAD drawing showing the cutting edge portion of the end mill of Example 1.

[0034] Fig. 11B This is a diagram showing a microlens array produced using the end mill of Example 1. DETAILED DESCRIPTION

[0035] (End Mill)

[0036] The end mill of the present invention has a cutting blade portion, preferably a shank portion, and may further have other components as necessary.

[0037] The end mill is mounted on, for example, a milling machine or a machining center (M / C), and can be used for various cutting processes by moving it in three-dimensional directions such as a horizontal plane, a vertical plane, or a curved surface.

[0038] <Cutting edge>

[0039] The cutting edge portion is a convex shape having a curved surface obtained by dividing a cone with a plane, the cone having a tip portion and a circular bottom surface, the tip of the tip portion being located on a center line passing through the center of the bottom surface, the cone having a circumferential side surface including an expanded diameter region, the expanded diameter region having a larger diameter than the bottom surface, and the plane including the center line. In this specification, "circular" includes substantially circular, "conical" includes substantially conical, and "convex shape" includes substantially convex shape.

[0040] As a result, the range in which the cutting edge of the cutting edge portion of the end mill functions, namely the effective edge range (WA), can be expanded to a shape greater than 90 degrees and less than 180 degrees. Even if the rotation axis of the cutting edge portion of the end mill is inclined relative to the processing surface of the mold matrix for cutting processing, deeper and higher-quality microlens cutting processing can be performed without causing processing defects caused by the rotation center of the cutting edge portion of the end mill.

[0041] The shape of the convex portion having the curved surface is not particularly limited as long as at least a portion has a curved surface, and can be appropriately selected according to the purpose. For example, a substantially semiconical shape, a substantially semi-elliptical cone shape, a kamaboko (Japanese original: Kamaboko) shape, etc. can be cited.

[0042] In the cutting edge portion, the surface shape of the circumferential side surface in the cross section that is orthogonal to the plane containing the center line and the bottom surface and contains the center line is preferably a curved shape. In this specification, "orthogonal" includes substantially orthogonal. When the surface shape of the circumferential side surface is a curved shape, a deeper and high-quality microlens can be cut.

[0043] The curved shape is preferably an arc shape or an elliptical arc shape, and more preferably an arc shape. Here, "arc" refers to a part of the circumference of a perfect circle. "Elliptical arc" refers to a part of the circumferential side of an ellipse. When the curved shape is an arc shape or an elliptical arc shape, a deeper and higher-quality microlens can be cut with high precision.

[0044] The end mill can rotate around the rotation axis, and the angle (effective blade range (WA)) formed by the straight line connecting the end of the cutting blade portion on the rotation axis side and the center of the cutting blade portion and the straight line connecting the other end and the center of the cutting blade portion is preferably greater than 90 degrees and less than 180 degrees, and more preferably greater than 100 degrees and less than 150 degrees. Thus, even if the rotation axis of the cutting blade portion of the end mill is tilted relative to the processing surface of the mold matrix for cutting, it is possible to perform deeper and high-quality cutting of the microlens without causing processing defects caused by the rotation center of the cutting blade portion of the end mill.

[0045] The rotation axis of the end mill refers to the center of rotation of the end mill when rotational motion is applied to the end mill.

[0046] The center of the cutting blade portion refers to a point on a curve formed by one end portion and the other end portion of the cutting blade portion that is equidistant from the one end portion and the other end portion of the cutting blade portion.

[0047] Furthermore, by providing the cutting edge portion on one side relative to the rotation axis, the cutting edge portion becomes a single-edged edge, and can be applied to the production of a minute microlens with an outer diameter of 100 μm or less.

[0048] The maximum diameter of the surface shape of the circumferential side surface of the cutting edge portion is preferably 100 μm or less, more preferably 10 μm or more and 100 μm or less, and further preferably 10 μm or more and 50 μm or less. When the maximum diameter of the surface shape of the circumferential side surface of the cutting edge portion is 100 μm or less, it can be applied to the cutting of tiny microlenses with an outer diameter of 100 μm or less.

[0049] As the material of the cutting edge portion of the end mill, for example, single crystal diamond, polycrystalline diamond, cubic boron nitride (CBN), ceramics (alumina, titanium carbide, silicon nitride), cermet, cemented carbide, high speed tool steel (HSS), carbon tool steel, etc. can be cited. Among these, single crystal diamond is particularly preferred. When single crystal diamond is used as the material of the cutting edge portion, a beautiful cutting surface can be processed compared to polycrystalline diamond.

[0050] The cutting blade portion having the above-mentioned shape and structure can be produced by, for example, fine precision grinding technology.

[0051] <Handle>

[0052] The shank portion is a portion of the end mill other than the cutting blade portion, and is a portion that rotatably holds the end mill on a machining center (M / C) or a milling machine, for example.

[0053] The shape, size (length, diameter), material, etc. of the shank are not particularly limited and can be appropriately selected according to the purpose, but are preferably designed with high precision in order to suppress vibration when the end mill is rotated at a higher speed.

[0054] The cutting blade is preferably fixed to the shank by brazing. When brazing is used, the cutting blade can be fixed to the shank more firmly than by screwing.

[0055] <Other components>

[0056] The other members are not particularly limited and can be appropriately selected depending on the purpose. For example, a neck portion provided between the handle portion and the cutting blade portion can be mentioned.

[0057] Here, the end mill of the present invention will be described in detail with reference to the drawings. Figure 7 1 is a schematic diagram showing an example of an end mill of the present invention. Figure 7 The end mill 10 includes a cutting blade 1 and a shank 2. The cutting blade 1 is fixed to the shank 2 by brazing. The cutting blade is a single-edged blade and is in a substantially convex shape with a curved surface.

[0058] like Fig. 8A As shown, the cutting blade portion 1 is a semiconical body ( Figure 8B ), the cone 6 has a tip portion 3 and a circular bottom surface 4, the tip 3a of the tip portion 3 is located on the center line CL that passes through the center C of the bottom surface 4, the cone 6 has a circumferential side surface 5 including an expanded diameter area, the expanded diameter area has a larger diameter than the bottom surface 4, and the above plane includes the center line CL. In addition, Figure 8C The plane P containing the center line CL is Figure 8B FIG. 2 is a diagram showing a cutting blade portion 1 having a substantially convex shape (substantially a semiconical shape) with a curved surface divided into two equal parts.

[0059] like Figure 8B and Figure 8C As shown, in the cutting edge portion 1, the surface shape of the circumferential side surface 5 in a cross section orthogonal to the plane P including the center line CL and the bottom surface 4 and including the center line CL is preferably curved, more preferably circular arc or elliptical arc.

[0060] In the cutting edge portion 1, as Fig. 9AAs shown, the angle (effective blade range (WA)) formed by the straight line L1 connecting the end of the cutting blade portion 1 of the end mill on the rotation axis side with the center C1 of the virtual circle 7 of the cutting blade portion and the straight line L2 connecting the other end with the center C1 of the virtual circle 7 of the cutting blade portion 1 is preferably greater than 90 degrees and less than 180 degrees, more preferably greater than 100 degrees and less than 150 degrees, and further preferably greater than 110 degrees and less than 140 degrees.

[0061] like Fig. 9A As shown, when the above-mentioned angle is greater than 90 degrees and less than 180 degrees, the range in which the cutting blade functions (effective blade range (WA)) is expanded, so that the inclination of the rotation axis of the cutting blade portion of the end mill can be made steeper, enabling deep groove processing of tiny microlenses.

[0062] In addition, if Fig. 9B As shown, the cutting edge 1 preferably has a cutting edge on one side relative to the rotation axis of the cutting edge of the end mill. Thus, the cutting edge of the end mill becomes a single-edged blade, which can be used to produce a micro lens with an outer diameter of 100 μm or less.

[0063] According to the end mill of the present invention, it is possible to realize the cutting of deeper micro lenses which is difficult to implement with conventional cutting tools. In addition, for the cutting of micro lenses using the end mill of the present invention, by expanding the effective blade range (WA) of the cutting blade of the end mill, it is possible to realize deep groove processing of micro lenses up to 1 / 2 of the radius of the cutting blade of the end mill without causing processing defects caused by the rotation center of the end mill.

[0064] Therefore, the end mill of the present invention is suitable as an end mill for processing microlenses.

[0065] (Method for manufacturing mold for producing microlens and device for manufacturing mold for producing microlens)

[0066] The method for manufacturing a microlens production mold of the present invention comprises using the end mill of the present invention to process the processing surface of a mold matrix in such a manner that the rotation center of the end mill is not located on the processing surface and the rotation axis of the end mill is tilted at an angle greater than 0 degrees and less than 90 degrees.

[0067] At this time, it is preferable to perform machining while inclining the rotation axis of the cutting blade portion of the end mill at an angle of 40 degrees or more and 80 degrees or less.

[0068] According to the method for manufacturing a mold for producing a microlens of the present invention, deep groove processing of a tiny microlens to about 1 / 2 of the radius (R) of the cutting edge of the end mill can be performed without generating processing defects on the processing surface of the workpiece caused by the rotation center of the cutting edge of the end mill.

[0069] Examples of the material of the mold matrix to be cut include copper, iron, aluminum, aluminum alloy, stainless steel, etc. The surface of the mold matrix preferably has a surface layer made of nickel-phosphorus (Ni—P) plating or copper (Cu) plating.

[0070] The size of the mold is not particularly limited and can be appropriately selected depending on the purpose.

[0071] Examples of the shape of the mold matrix include a flat shape, a stamped shape, and a roll shape.

[0072] The manufacturing device of the mold for producing microlens of the present invention comprises the end mill of the present invention and further comprises other units as required. In addition, as the manufacturing device of the mold for producing microlens, for example, a machining center (M / C) or a milling machine can be directly used.

[0073] The other means may include, for example, a fixing portion provided to extend in a vertical direction relative to a base of the manufacturing apparatus for manufacturing the microlens mold, a stage supported by the fixing portion, and a rotation support member.

[0074] The table is supported by the fixing portion so as to be movable in each of three directions of X, Y, and Z by the driving unit. A mold matrix as a processing object is fixed on the table.

[0075] The rotation support member is supported by the fixed portion in a manner that allows the member to rotate about an axis along the X-axis. The end mill is rotatably fixed to the rotation support member in a manner that the rotation axis extends in a direction orthogonal to the axis along the X-axis. The form of the rotation support member is not limited thereto, and for example, the rotation support member may also rotate about an axis along the Y-axis.

[0076] The microlens manufactured by the method and apparatus for manufacturing a microlens manufacturing mold of the present invention is, for example, a semicircular shape with an outer diameter of less than 100 μm, a depth of 10 μm to 50 μm, and a high-quality microlens that does not produce processing defects caused by the rotation center of the end mill.

[0077] In addition, a microlens array formed by arranging a plurality of microlenses can be applied to fields that control light by focusing, diffusing, reflecting, diffracting, etc., such as liquid crystal displays, optical coupling optical elements, image input devices, etc.

[0078] [Example]

[0079] Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

[0080] (Comparative Example 1)

[0081] In Comparative Example 1, a Fig. 10A The CAD drawing of the cutting edge portion shows a conventional end mill with a cutting edge portion having a radius of 50 μm (R50) and an effective edge range (WA) of 90°. The cutting edge portion of the end mill is made of single crystal diamond.

[0082] The mold base to be cut was made of copper and had a cylindrical shape with a diameter of 132 mm and a length of 250 mm.

[0083] A lathe was used as a manufacturing device for the mold for producing a microlens. The mold matrix was fixed to the lathe and an end mill was held thereon. The end mill was rotated at a speed of 100,000 min. -1 The cutting process is performed by rotating at the above speed.

[0084] like Fig. 10A As shown in FIG. 1 , the effective blade range (WA) of the cutting edge of the end mill of Comparative Example 1 is 90°, and the microlens cutting process is performed by tilting the rotation axis of the cutting edge of the end mill at 45° relative to the processing surface of the mold matrix. As a result, when the cutting depth reaches about 14 μm, as shown in FIG. Fig. 10B As shown, processing defects (cutting marks) are generated on the processing surface of the mold base due to interference of the rotation center, making it difficult to perform deep groove processing of the microlens.

[0085] (Example 1)

[0086] In Comparative Example 1, a Fig.11A The cutting edge portion of the end mill shown in the CAD drawing has a radius of 50μm (R50) and an effective blade range (WA) of 120°. The microlens cutting process was performed in the same manner as in Comparative Example 1, except that the rotation center of the end mill is not located on the processing surface and the rotation axis of the cutting edge portion of the end mill is inclined 60° relative to the processing surface of the mold matrix.

[0087] The results, such as Fig. 11B As shown, a microlens array with a beautiful honeycomb structure with a depth of 24 μm can be cut without generating machining defects on the machining surface of the mold matrix caused by the rotation center of the end mill.

[0088] It can be seen from this that the end mill of Example 1, which expands the effective blade range (WA) of the cutting edge portion to 120°, is able to cut to a depth of 1 / 2 (25 μm) of the radius of 50 μm (R50) of the cutting edge portion of the end mill without causing processing defects on the processing surface caused by the rotation center of the end mill, by making the rotation center of the end mill not located on the processing surface and making the rotation axis of the cutting edge portion of the end mill inclined 60° relative to the processing surface of the mold matrix.

[0089] Hereinafter, preferred embodiments of the present invention will be described.

[0090] <1> An end mill, characterized by comprising:

[0091] A cutting blade portion in a convex shape, wherein the convex shape has a curved surface obtained by dividing a cone with a plane, the cone has a tip portion and a circular bottom surface, the tip of the tip portion is located on a center line passing through the center of the bottom surface, the cone has a circumferential side surface including an expanded diameter area, the expanded diameter area has a diameter larger than the bottom surface, and the plane includes the center line.

[0092] <2> The end mill according to <1> above, wherein in the cutting edge portion,

[0093] The surface shape of the circumferential side surface in a cross section that is orthogonal to a plane that includes the center line and the bottom surface and that includes the center line is curved.

[0094] <3> The end mill according to <2> above, wherein the curved line is an arc shape or an elliptical arc shape.

[0095] <4> An end mill according to any one of <1> to <3> above, wherein the end mill is capable of rotating around a rotation axis, an angle formed by a straight line connecting an end of the cutting blade portion on the rotation axis side and the center of the cutting blade portion and a straight line connecting the other end and the center of the cutting blade portion is greater than 90 degrees and less than 180 degrees, and the cutting blade portion is provided on one side relative to the rotation axis.

[0096] <5> The end mill according to <4> above, wherein the formed angle is not less than 100 degrees and not more than 150 degrees.

[0097] <6> The end mill according to <2> above, wherein a maximum diameter of the surface shape of the circumferential side surface is 100 μm or less.

[0098] <7> The end mill according to any one of <1> to <6>, wherein the cutting blade portion includes single crystal diamond.

[0099] <8> The end mill according to any one of <1> to <7>, comprising a shank portion, wherein the cutting blade portion is fixed to the shank portion by brazing.

[0100] <9> The end mill according to any one of <1> to <8>, wherein the end mill is used for microlens processing.

[0101] <10> A method for manufacturing a mold for manufacturing a microlens, characterized by using the end mill described in any one of <1> to <9> above,

[0102] The machining is performed by tilting the rotation axis of the end mill at an angle greater than 0 degrees and less than 90 degrees with respect to the machining surface of the mold base so that the rotation center of the end mill is not located on the machining surface.

[0103] <11> A device for manufacturing a mold for manufacturing a microlens, comprising the end mill according to any one of <1> to <9>.

[0104] This application claims priority based on Japanese Patent Application No. 2022-116247 filed on July 21, 2022, the entire contents of which are hereby incorporated by reference.

[0105] Explanation of symbols

[0106] 1: Cutting edge

[0107] 2: Handle

[0108] 3: Tip

[0109] 4: Bottom

[0110] 5: Circumferential side

[0111] 6: Cone

[0112] 7: Virtual circle

[0113] 10: End mill

[0114] CL: Centerline.

Claims

1. An end mill, characterized in that: The end mill has a cutting edge portion in a convex shape, wherein the convex shape has a curved surface obtained by dividing a cone with a plane. The cone has a tip portion and a circular bottom surface, the tip of the tip portion is located on a center line that passes through the center of the bottom surface, the cone has a circumferential side surface, the circumferential side surface includes an expanded diameter area, and the expanded diameter area has a larger diameter than the bottom surface, The plane contains the centerline.

2. The end mill according to claim 1, wherein: In the cutting edge portion, The surface shape of the circumferential side surface in a cross section that is orthogonal to a plane including the center line and the bottom surface and includes the center line is a curved line.

3. The end mill according to claim 2, wherein: The curved shape is a circular arc or an elliptical arc.

4. The end mill according to any one of claims 1 to 3, wherein: The end mill is capable of rotating around a rotation axis, and an angle formed by a straight line connecting an end of the cutting blade portion on the rotation axis side and the center of the cutting blade portion and a straight line connecting the other end and the center of the cutting blade portion is greater than 90 degrees and less than 180 degrees, and the cutting blade portion is provided on one side relative to the rotation axis.

5. The end mill according to claim 4, wherein: The angle formed is greater than or equal to 100 degrees and less than or equal to 150 degrees.

6. The end mill according to claim 2, wherein: The maximum diameter of the surface shape of the circumferential side surface is 100 μm or less.

7. The end mill according to any one of claims 1 to 3, wherein: The cutting edge portion includes single crystal diamond.

8. The end mill according to any one of claims 1 to 3, wherein: The end mill has a shank portion, and the cutting blade portion is fixed to the shank portion by brazing.

9. The end mill according to any one of claims 1 to 3, wherein: The end mill is used for microlens processing.

10. A method for manufacturing a mold for manufacturing a microlens, characterized in that: Using the end mill according to any one of claims 1 to 3, The machining is performed by tilting the rotation axis of the end mill at an angle greater than 0 degrees and less than 90 degrees with respect to the machining surface of the mold base so that the rotation center of the end mill is not located on the machining surface.

11. A manufacturing device for a mold for manufacturing a microlens, characterized in that: An end mill according to any one of claims 1 to 3.

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