Composite grinding wheel, method for manufacturing optical lens using the same, and centering device

Abstract

To provide a composite grinding wheel which enables grinding such as rough grinding, middle grinding and finish grinding with one grindstone, gives a uniform and smooth ground surface by the finish grinding, and can suppress generation of white spot defects in a subsequent blacking (black layer forming) step, a method for manufacturing an optical lens using the same, and a centering device.SOLUTION: There is provided a composite grinding wheel for grinding an optical lens, wherein the optical lens has a contour part on the outer peripheral side and a plane part, the composite grinding wheel has a plurality of grinding parts, and the plurality of grinding parts have a first plane grinding part for rough grinding or middle grinding at least the plane part of the optical lens and a second plane grinding part for finish grinding the plane part.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a composite grinding wheel used for grinding optical lenses. The present invention also relates to a method for manufacturing an optical lens and a centering device using the same. [Background technology]

[0002] 2. Description of the Related Art An in-vehicle camera unit is attached to the front or rear of a vehicle as a system for assisting a driver. These vehicle-mounted camera units are widely used not only to supplement the visibility around the vehicle, but also to obtain information on obstacles ahead and vehicles ahead, as well as information on vehicles behind the vehicle, and for parking assistance. The optical lenses used in this type of vehicle-mounted camera are often composed of a first lens that is exposed to the outside and multiple sub-lenses located inside it. The first lens has a convex surface on the front side, a flat surface on the back side, and a concave surface on the inner periphery thereof. When such an optical lens is housed in a holder, an anti-reflection layer is formed on the flat surface of the lens by painting it black or the like. Therefore, if there are pit-like defects on the ground surface of the flat portion, there is a problem in that white spots appear on the black surface when viewed from the front of the lens. Conventionally, the grinding process for this type of optical lens has used different grinding wheels for each grinding step, such as rough grinding, medium grinding, and finish grinding, but this requires the grinding wheels to be replaced frequently and multiple grinding machines.

[0003] Patent Document 1 discloses a tandem grinding wheel having a first abrasive layer with a grit size of #270 and a second abrasive layer with a grit size of #400, but the purpose of this is to increase the processing speed of lenses that require a large amount of removal, such as molded lenses, and not to improve the processing quality of the flat surface of an optical lens. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-90467 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide a composite grinding wheel that can perform grinding processes such as rough grinding, medium grinding, and finish grinding with a single grinding wheel, produces a uniform and smooth grinding surface in the finish grinding, and suppresses the occurrence of white spots in the subsequent black coating (formation of a black layer) process, as well as a manufacturing method for optical lenses using the same and a core removal processing device. [Means for solving the problem]

[0006] The composite grinding wheel of the present invention is a composite grinding wheel for grinding optical lenses, wherein the optical lens has an outer peripheral outer portion and a flat portion, and the composite grinding wheel has a plurality of grinding portions, each of which has at least a first surface grinding portion for rough or medium grinding and a second surface grinding portion for finish grinding the flat portion of the optical lens. For rough grinding or medium grinding, it is preferable to use a grindstone with an abrasive grain size of #80 to #500, and for finish grinding, it is preferable to use a grindstone with a finer grain size than those used for rough grinding or medium grinding, for example, one with a grain size of #500 to #1200.

[0007] The composite grinding wheel according to the present invention is characterized in that it is intended for grinding optical lenses having a flat surface on the back side.

[0008] In the present invention, the composite grinding wheel preferably further includes a first outer contour grinding portion for performing rough or medium grinding and / or a second outer contour grinding portion for performing finish grinding of the outer contour of the optical lens.

[0009] In the present invention, the first surface ground portion and / or the second surface ground portion may have a traverse ground portion and a relief recess on the inner peripheral side thereof. Here, the traverse grinding section refers to grinding by traversing (moving laterally) the horizontal grinding surface of a rotating grinding wheel along the flat surface of the optical lens, and is opposed to pressure grinding, in which the grinding surface of the grinding wheel is pressed against the surface of the optical lens to be ground. Therefore, if an escape recess is formed on the inner peripheral side of this composite grinding wheel, in the direction in which the draver grinding portion advances relative to the optical lens, grinding powder is easily swept into this escape recess, making it easier to supply grinding water to the grinding surface.

[0010] The method for manufacturing an optical lens according to the present invention is a method for manufacturing an optical lens using a composite grinding wheel as described in any one of claims 1 to 3, characterized in that a flat surface of the optical lens is roughly or medium ground in a first flat surface grinding section and then finish ground in a second flat surface grinding section, thereby suppressing the occurrence of white spots when a black layer is then formed on the flat surface.

[0011] In addition, the core removal processing apparatus of the present invention is characterized in that it comprises a rotation-controlled wheel grinding wheel consisting of a composite grinding wheel described in any one of claims 1 to 3, a position control means for the X-axis, which is the cutting direction of the wheel grinding wheel, and a Y-axis, which is perpendicular to the cutting direction, and a holding means for chuck an optical lens. Effect of the Invention

[0012] The composite grinding wheel according to the present invention can perform a series of grinding steps, namely rough grinding, medium grinding and finish grinding, of an optical lens, with a single composite grinding wheel. In particular, the finishing quality of the flat surface of the optical lens is improved, and the defect known as marbling, which occurs when white spots appear on the coated surface during the subsequent blackening process, can be reduced. [Brief description of the drawings]

[0013] [Figure 1] 1 shows an example of the configuration of an optical lens centering device using the composite grinding wheel according to the present invention as a wheel grinding wheel, where (a) shows a holding means for the optical lens, and (b) shows a schematic diagram of the state in which the optical lens is rotated and ground by the composite grinding wheel. [Diagram 2](a) shows the external appearance of the composite grinding wheel (wheel grinding wheel), (b) shows its front view, and (c) shows the AA line cross-sectional view. [Diagram 3] 1A and 1B show the steps for rough or medium grinding of the flat surface of an optical lens, and 1C shows the steps for rough or medium grinding of the outer peripheral surface of the optical lens and chamfer grinding of the upper surface. [Figure 4] (a) to (c) show the flow of finish grinding of the flat surface of an optical lens. [Diagram 5] As Example 2, (a) and (b) show an example of rough or medium grinding of a flat surface of an optical lens by traverse grinding, and (c) shows an example of chamfer grinding of an outer peripheral portion and an upper surface of an optical lens. [Figure 6] 1(a) to 1(c) show an example of finish grinding of a flat surface of an optical lens by traverse grinding. [Figure 7] As Example 3, an example of a composite grinding wheel in which a first surface grinding section (rough and medium grinding) and a second surface grinding section (finish grinding) are arranged upside down compared to Example 1 will be described. [Figure 8] Shown are examples of micrographs of a ground surface that has been roughly ground with grit size #400 and a ground surface that has been finish ground with grit size #800. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention is intended to perform core removal processing of optical lenses, and is characterized in that a single grinding wheel is formed as a composite wheel that is used to perform finish grinding after rough grinding and medium grinding in order to prevent the occurrence of white spots when a black layer is formed on the flat surface of the optical lens in a subsequent process, and that a rough or medium grinding portion and a finish grinding portion are combined in one grinding wheel. Therefore, the composite grinding wheel according to the present invention is not limited in structure as long as it can meet the above-mentioned objective.

[0015] FIG. 1 shows an example of the configuration of an optical lens centering device using a composite grinding wheel 10 according to the present invention. An example in which the composite grinding wheel 10 is manufactured as a wheel-type grinding wheel as shown in FIG. 2 will be described. The optical lens holding means has a bell clamp structure consisting of a support portion 2 below the optical lens 1 and a clamp 3 that descends from above. The holding means rotates in the state shown in FIG. 1(b), and the chuck state of the optical lens is centered. Thereafter, the optical lens is ground by the rotating composite grindstone 10 while the rotation of the optical lens is controlled. Therefore, in the rotating mechanism of the composite grinding wheel 10, in FIG. 1(b), the position is controlled at least in the X-axis direction, which is the horizontal cutting direction of the grinding wheel, and in the Y-axis direction, which is perpendicular to the vertical direction. Although the centering device shown in FIG. 1 is an example in which the optical lens is clamped in the vertical direction, it can also be clamped in the horizontal direction.

[0016] FIG. 2 shows an example of the shape of the composite grinding wheel 10 as a first embodiment. This embodiment has a wheel portion 11, a mounting hole 11a in the center thereof, and a ground portion 20 on the outer circumferential surface. An enlarged view of the grinding portion 20 is shown in FIG. The grinding portion 20 is an electroplated grindstone having abrasive grains fixed to a base metal by a plating layer. In Figure 3(a), the grinding area is divided by a horizontal dotted line, and abrasive grains for rough grinding are electrodeposited on the outer peripheral surface of the upper R1 area, while abrasive grains for finish grinding are electrodeposited on the outer peripheral surface of the lower R2 area.

[0017] Optical lens 1 has a convex upper surface, a concave portion in the center of the lower surface, a flat portion 1b on the outer periphery thereof, and a circular outer portion 1a on the side surface. The optical lens 1 to which the present invention is applied is an optical lens having a flat portion on the lower surface side, and having a black layer formed thereon by black painting or the like in a post-process after grinding.

[0018] Next, the flow of the grinding process will be described. As shown in Figure 3(a), the R1 area for rough grinding has a first surface grinding portion 21a consisting of a horizontal surface for rough grinding the flat portion 1b of the optical lens 1, and a first contour grinding portion 21b in the vertical direction for rough grinding the outer peripheral portion 1a of the optical lens 1, and also has a chamfer grinding portion 21c for chamfer grinding the upper side (convex portion side) of the outer portion 1a as necessary. The chamfered shape may be a C-chamfer or a stepped chamfer shape. The composite grinding wheel 10 advances in the X-axis direction relative to the optical lens 1 that is being rotated and held, and the first surface grinding portion 21a of the grinding wheel, which is rotationally controlled as shown in Figure 3(b), is pressed against the lens from below in the Y-axis direction to perform rough grinding. This ground surface is designated as 1b-g1. Next, after the composite grinding wheel 10 is retreated, contour grinding and chamfer grinding are performed in the first contour grinding section 21b and the chamfer grinding section 21c, as shown in FIG. 3(c). This ground surface is designated as 1a-g1.

[0019] Next, the finish grinding will be described. The R2 region of the composite grinding wheel 10 has a second horizontal surface grinding portion 22a for finish grinding. If necessary, a second outer contour ground portion 22b may be provided in the vertical direction. This second outer shape grinding section 22b can be used when finish grinding of the outer shape portion 1a of the optical lens is required. In the embodiment shown in Figure 4, the composite grinding wheel 10 is advanced in the X-axis direction as shown in Figure 4(a), and the optical lens 1 and the composite grinding wheel 10 are rotated relative to each other as shown in Figure 4(b), while pressing the second surface grinding portion 22a against the flat surface of the optical lens 1. As a result, the flat surface is finish-ground to become a ground surface 1b-g2. By using the composite grinding wheel 10 according to the present invention, rough grinding and finish grinding can be performed continuously with one composite grinding wheel.

[0020] An example of the shape of the grinding portion 20 of the composite grindstone of the second embodiment is shown in FIG. Description of the same parts as in the first embodiment will be omitted, and the differences will be mainly described. This example has a slightly lower step grinding portion 21d at the outer peripheral end of the first surface grinding portion 21a in the R1 region, and the second surface grinding portion 22a in the R2 region is a traverse grinding portion, with a recessed escape recess 22c formed inside it. In the rough grinding, a rotating composite grinding wheel 10 cuts into the flat surface portion 1b of the optical lens 1 while traverse grinding is performed as shown in FIG. 5(a). FIG. 5(b) shows the state after rough grinding has been completed, with a ring-shaped protrusion 1c remaining on the flat surface of the optical lens at the stepped ground portion 21d. This is to prevent chipping (defects) from occurring at the boundary between the flat surface portion 1b and the inner concave surface portion. FIG. 5(c) shows a state in which rough grinding and chamfer grinding of the outer portion 1a are being carried out. If necessary, grinding of the outer portion 1a may be performed first, and then traverse grinding as shown in Figs. 5(a) and 5(b) may be performed.

[0021] Next, as shown in FIG. 6(a), the composite grinding wheel 10 is advanced so as to move the second surface grinding portion (traverse grinding portion) 22a in the traverse direction. At this time, grinding debris falls easily into the recess 22c, and grinding water and the like also flows in easily. Furthermore, since the ring-shaped protrusion 1c is ground in the finish grinding stage, chipping is reduced.

[0022] FIG. 7 shows an example of a composite grinding wheel 10 according to the third embodiment. In this Example 3, the R1 region for rough grinding and medium grinding is provided below the dotted line as shown in FIG. 7(b), and the R2 region for finish grinding is provided above the dotted line, and the abrasive grains are fixed to the base metal by electroplating. In this case, too, as shown in FIG. 7(c), a relief recess 22c may be formed on the inner peripheral side of the second surface ground portion 22a, and traverse grinding may be performed.

[0023] FIG. 8 shows a photograph of the flat surface 1b of the optical lens 1 which has been roughly ground with #400 grit and then finish ground with #800 grit using the composite grinding wheel 10 according to the present invention. The surface ground with #400 grit had a surface roughness of Ra: 1.2074 μm and Rz: 27.2743 μm, and chipping as large as 76 μm was also observed. In contrast, the surface ground with #800 grit had a surface roughness of Ra: 0.8928 μm and Rz: 15.1845 μm, which was smaller and the occurrence of chipping was reduced. It is estimated that finish grinding with #800 grit will reduce white spot defects during the subsequent black coating process. [Explanation of symbols]

[0024] 1 Optical Lenses 1a External shape 1b Plane part 10 Composite grinding wheel (wheel grinding wheel) 11 Wheel section 11a Mounting hole 20 Grinding section 21a First surface grinding section 21b First external grinding section 21c Chamfer grinding section 22a Second surface grinding section

Claims

1. A composite grinding wheel for grinding optical lenses, comprising: The optical lens has an outer peripheral portion and a flat portion, The composite grinding wheel has a plurality of grinding portions, The composite grinding wheel is characterized in that the plurality of grinding sections include a first surface grinding section for rough or medium grinding and a second surface grinding section for finish grinding at least the flat surface of the optical lens.

2. 2. The composite grinding wheel according to claim 1, further comprising a first outer contour grinding portion for rough or medium grinding of the outer contour of the optical lens and / or a second outer contour grinding portion for finish grinding of the outer contour of the optical lens.

3. 2. The composite grinding wheel according to claim 1, wherein the first surface grinding portion and / or the second surface grinding portion has a traverse grinding portion and a relief recess on the inner peripheral side thereof.

4. A method for manufacturing an optical lens using the composite grindstone according to any one of claims 1 to 3, A method for manufacturing an optical lens, characterized in that a flat surface of the optical lens is roughly or intermediately ground in a first surface grinding section and then finish-ground in a second surface grinding section, thereby suppressing the occurrence of white spots when a black layer is then formed on the flat surface.

5. An optical lens centering device comprising: a rotation-controlled wheel grinding wheel made of the composite grinding wheel according to any one of claims 1 to 3; position control means for the X-axis cutting direction of the wheel grinding wheel and a Y-axis perpendicular to the cutting direction; and holding means for chuck- ing an optical lens.

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