JP2006150481A - Method and device for forming abrasive wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for forming a abrasive wheel which can be applied to highly accurate optical element machining without uniform forming marks in the rotational direction of the abrasive wheel. <P>SOLUTION: The method for forming an abrasive wheel is used for forming an annular abrasive wheel (8) by rotating the annular abrasive wheel (8) used for aspheric surface grinding and a straight cup abrasive wheel (4) on the forming device (1). The straight cup abrasive wheel (4) can be rotationally driven around a first rotary shaft (a Z-axis) so that the forming face of the straight cup abrasive wheel (4) comes into contact with the annular abrasive wheel (8) on both ends of its diameter. The annular abrasive wheel (8) can be rotationally driven around a second rotary shaft (an X-axis) crossing with the first rotary shaft (the Z-axis). The annular abrasive wheel (8) can be formed by executing movement control for relatively moving the straight cup abrasive wheel (4) and the annular abrasive wheel (8) at least in the direction of approaching/separating from each other, in the mutually crossing direction, and in the direction (a B-axis) of changing an angle of the second rotary shaft (the X-axis) of the annular abrasive wheel (8) to the straight cup abrasive wheel (4). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for forming a grindstone used for grinding processing of an optical element and the like, and more particularly to a method and apparatus for forming a grindstone applicable to high-precision grinding.

Optical parts such as lenses and prisms are required to have very high shape accuracy and surface roughness accuracy. As a method of processing such a high-precision optical component, an aspherical surface is used while moving the grindstone in a direction crossing the rotation direction of the workpiece using an annular grindstone and encircling the grindstone machining surface with respect to the workpiece in an arc. A method of performing grinding (parallel grinding method) is disclosed. In this forming method, since the cross-sectional shape of the grindstone 16 is transferred to the workpiece 17 as shown in FIG. 6, it is necessary to use a grindstone having a highly accurate arc-shaped cross-sectional shape. (For example, refer nonpatent literature 1.)
As such a highly accurate grinding wheel shaping and sharpening method, there is a spherical grinding wheel (a) shaping (b) sharpening method shown in FIG. In this method, the cup-type grindstone 18 is cut in one direction with respect to the spherical-shaped grindstone 19 to be formed (cut from the left to the right in the figure) to create a spherical shape, which is conspicuous by the slurry 20. (For example, refer to Patent Document 1.)
In recent years, the shape of aspherical lenses and curved prisms has been diversified for the purpose of improving optical performance. As shown in FIG. 8, when a spherical grinding wheel 21 is used, it interferes with the aspherical work piece 22, If the radius of the grindstone is made small in order to avoid this, there is a problem that sufficient processing accuracy cannot be obtained due to large wear of the grindstone. Therefore, it is necessary to use an annular grindstone having a processed surface with an arc cross-sectional shape smaller than the diameter of the grindstone.

As means for forming the processing surface of the grindstone into an annular shape, a single stone diamond dresser method shown in FIG. 9A and a stainless roll method shown in FIG. 9B are known. As shown in FIG. 9 (a), an annular molding method using a single stone diamond dresser is performed such that the processed surface of the rotating annular grindstone 23 is in contact with the single stone diamond dresser 24 and the processed surface has a desired R shape. The annular shape is formed by relatively moving as described above. Further, in the stainless roll method shown in FIG. 9B, an annular shape is formed on the grindstone processed surface by relatively moving in an arc while contacting the rotating annular grindstone 23 and the stainless roll 25. . (For example, see Patent Document 2.)
JP 2001-260023 A JP 2003-260646 A Journal of Precision Engineering Vol. 68, no. 8, 2002 (pages 1067-1071) "Study on aspherical die machining by parallel grinding method" Yu Saeki, Tsunemoto Tsujikawa, Katsuo Shoji

  By the way, in order to obtain a highly accurate processing result by the parallel grinding method, the cross-sectional shape of the grindstone is highly accurate, and at the same time, no waviness is formed on the work surface of the workpiece. It is necessary that there are no periodic irregularities in the same direction as the rotation direction. However, in the annular grindstone forming means according to the technique of Patent Document 2, as shown in FIGS. 9A and 9B, uniform rotation by the single stone diamond dresser 24 and the stainless steel roll 25 is performed in the rotation direction of the annular grindstone 23. A molding mark 26 is formed. When these grindstones are used for aspherical grinding, the molding marks 26 on the grindstone surface are transferred to the workpiece, so that waviness is formed on the surface of the processed optical element, and sufficient optical performance cannot be obtained. .

  An object of the present invention is to provide a grinding wheel molding method and a molding apparatus that can be applied to high-precision optical element processing without the presence of uniform molding traces in the rotational direction of the grinding stone in view of the above-described conventional situation. is there.

  The first grinding wheel molding method of the present invention is a grinding wheel molding method for molding the annular grinding wheel by rotating an annular grinding wheel and a cup-type grinding wheel used for aspherical grinding on a molding device. The cup-type grindstone that can be driven to rotate around the first rotation axis so that the molding surface of the cup-type grindstone is in contact with the annular grindstone at both ends of the diameter, and the first rotation axis intersects with the first rotation axis. The annular grindstone that can be driven to rotate about two rotation axes, at least the direction in which they are separated from each other, the direction that intersects each other, and the angle of the second rotation axis of the annular grindstone with respect to the cup-shaped grindstone. The annular grindstone is formed by performing movement control for relative movement in a changing direction.

  According to this configuration, at the contact point between the annular grindstone and the cup-shaped grindstone, molding is performed in a direction in which the rotation directions of the annular grindstone intersect with each other. A high-precision annular grindstone is formed.

  The second grinding wheel molding method of the present invention is the first grinding wheel molding method, wherein the movement control includes movement control of the cup-type grinding wheel in the first rotation axis direction, and the annular grinding wheel. It includes movement control in a direction orthogonal to the first rotation axis direction and swing control of the second rotation axis of the annular grindstone.

According to this configuration, the cup-type grindstone and the annular grindstone are moved in the respective rotation axis directions or the annular grindstone is swung in the rotation axis direction, so that a complicated structure is not obtained.
According to the third method for forming a grindstone in the present invention, in the first or second molding method, a GC (Green Silicon Carbide) is formed on a contact surface between the annular grindstone and the cup-shaped grindstone after forming the annular grindstone. ) It is characterized by interposing a slurry having abrasive grains.

According to this configuration, the processed surface of the annular grindstone is noticed with higher accuracy by the supplied GC slurry.
The fourth grinding wheel molding method according to the present invention is characterized in that, in the first to third grinding stone molding methods, the molding surface of the cup-type grinding stone has GC (Green Silicon Carbide) abrasive grains. .

According to this configuration, the grindstone to be molded is formed into an annular shape, and at the same time, it is conspicuous by the GC abrasive grains dropped from the cup-type grindstone.
According to a fifth aspect of the present invention, there is provided a fifth method for forming a grindstone, wherein the annular grindstone is formed by rotating an annular grindstone used for aspherical grinding and a diamond dresser on a molding apparatus. The diamond dresser that can be swiveled around the first rotation axis so that the forming surface of the diamond dresser is in contact with the annular grindstone at both ends of the swivel diameter, and the second that intersects the first rotation axis. The ring-shaped grindstone that can be driven to rotate around the rotation axis of the ring-shaped grindstone is changed at least in a direction in which the ring-shaped grindstone is separated from each other, a direction that intersects each other, and an angle of the second rotation axis of the ring-shaped grindstone with respect to the diamond dresser. The annular grindstone is formed by performing movement control for relative movement in the direction.

  According to this configuration, at the contact point between the annular grindstone and the diamond dresser, the molding is performed in the direction in which the respective rotation directions intersect with each other. Therefore, periodic molding marks are not formed in the rotation direction of the annular grindstone, A high-precision annular grindstone is formed.

  According to the present invention, the grinding wheel to be molded is formed into a high-accuracy annular shape having no uniform molding trace in the direction of rotation of the grinding stone, and high-precision aspherical grinding can be performed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram of the entire molding apparatus according to Embodiment 1, and FIG. 2 is a diagram for explaining the positional relationship between a cup-type grindstone and an annular grindstone. The workpiece shaft spindle 2 on the forming apparatus 1 is installed on the Z-axis slide table 3 so as to be movable back and forth in the rotation axis direction (Z-axis direction). A cup-type grindstone 4 having an inner diameter r made of a metal bond grindstone or vitrified bond grindstone for holding diamond grains of abrasive grain size # 325 is rotatably held at the tip of the workpiece spindle 2. An X-axis slide table 5 that moves in a direction orthogonal to the moving direction of the Z-axis slide table 3 is disposed, and the grindstone shaft spindle 6 is placed horizontally on a B-axis rotary table 7 that is installed on the X-axis slide table 5. Is arranged.

  The formed annular grindstone 8 is formed of a resin bond grindstone that holds diamond abrasive grains having an abrasive grain size of # 3000, and is rotatably held at the tip position of the grindstone shaft spindle 6 via a holding shaft 9. . The slurry supply nozzle 10 is a nozzle for supplying slurry for sharpening the grindstone. As the slurry, GC (Green Silicon Carbide) abrasive grains diluted with a diluent oil are used.

  The effect | action at the time of shaping | molding in Embodiment 1 mentioned above is demonstrated below. In FIG. 2, the shape of the annular grindstone 8 is determined by using the cross-sectional radius a of the donut-shaped ring and the distance b from the center of the ring in the XYZ coordinate system with the center of the annular grindstone 8 as the origin.

It is represented by
FIG. 3 is a view for explaining the positional relationship between the contact points of the cup-type grindstone and the annular grindstone in the shaping and sharpening process of the annular grindstone, (a) is a view seen from the negative direction of the Z axis, and (b) is Y It is the figure seen from the axial plus direction. As shown in FIG. 3, the movement of the XZB axis is controlled so that the Y-axis direction diameter end t of the inner diameter r of the cup-type grindstone is in contact with the desired annular shape. Since the contact is always made at the position of ±± r, the curve s representing the locus of the contact is replaced by y in the above equation (1), and the equations of x and z are expressed as follows.

  Therefore, the molding apparatus is arranged so that the Y-axis direction diameter end t of the inner diameter of the cup-type grindstone 4 is along the curve, and the direction of the rotation axis of the cup-type grindstone is the direction of the normal line set on the curve. An annular shape is formed by controlling the movement of the XZB axis. At this time, the rotational speed of the cup-type grindstone 4 was set to 500 to 1000 rpm, and the rotational speed of the annular grindstone 8 to be formed was set to 100 to 500 rpm. Further, the moving speed of each axis of XZB is set to 0.5 to 4.0 mm / min, and the Z-axis slide table is moved by 0.5 to 2.0 μm each time the B-axis rotary table is swung once, and the ring is formed. A cut was made in the grindstone 8.

  After forming the annular grindstone 8, as shown in FIG. 3B, while maintaining the contact between the annular grindstone 8 and the cup-type grindstone 4 by controlling the movement of each axis of XZB, the slurry supply nozzle 10 # 2000- #. The annular grindstone 8 was sharpened by supplying 4000 GC slurry 11 and interposing it on the grindstone contact surface. Sharpening was performed for 1 to 5 minutes.

  As described above, at the contact point between the annular grindstone 8 and the cup-type grindstone 4, molding is performed in the direction in which the rotation directions intersect with each other. It was not, but was able to obtain the highly accurate annular grindstone 8.

  In addition, the above equation (2) shows the calculation formula for the movement control coordinates of the circular grindstone 8 with the center of the circular grindstone 8 as the origin, but the tip of the circular grindstone 8 or the cross-sectional circle center of the ring It is possible to form the annular grindstone 8 in the same manner by converting the coordinate values of x and z even with the origin as the origin.

  FIG. 4 is a view for explaining the positional relationship between the contact points of the cup-type grindstone and the annular grindstone in Embodiment 2, and is a view seen from the Y-axis plus direction. In the second embodiment, the cup-type grindstone in the first embodiment is a cup-type GC grindstone in which a GC abrasive grain (Green Silicon Carbide) smaller than the grain mesh size of the grindstone to be formed is held by vitrified or a resinoid binder. 12 is composed. Other configurations are the same as those of the first embodiment.

  In the second embodiment, the movement of the XZB axis is controlled in the same manner as in the first embodiment, and at the same time, the ZZ axis slide table is moved with respect to the grinding wheel forming the Z axis slide table. Others are the same as in the first embodiment.

  According to the second embodiment, the cup-type GC grindstone 12 forms the annular grindstone 8, and the dropped GC abrasive grains supply the GC slurry 11 as a slurry. Therefore, as in the first embodiment, it is possible to obtain a highly accurate circular grindstone more efficiently.

  FIG. 5 is a diagram for explaining the positional relationship between the contact points of the single stone diamond dresser and the annular grindstone in the process of forming the annular grindstone according to the third embodiment, and FIG. ) Is a view seen from the Y axis plus direction. In the third embodiment, the cup-type grindstone in the first embodiment is replaced with a single stone diamond dresser 13. As shown in FIG. 5B, the single stone diamond dresser 13 is held at a position separated from the workpiece shaft rotation center by a distance r via a screw 15 at an arbitrary position of the dresser fixture 14.

  In the third embodiment, the single stone diamond dresser 13 is rotated at the turning radius r, and the XZB axis of the molding apparatus is adjusted so that both ends t of the rotation diameter are in contact with a desired annular shape as in the first embodiment. The movement is controlled and the annular grindstone 8 is formed. The sharpening process has the same configuration and operation as in the first or second embodiment.

  According to the third embodiment, as in the first and second embodiments, periodic molding marks are not formed in the rotation direction of the annular grindstone 8, and a highly accurate annular grindstone can be obtained. Since the turning radius of the single stone diamond dresser 13 can be arbitrarily set, it is possible to set the turning position to be optimal for avoiding the interference with the tool due to the B-axis movement.

In the embodiment, only the three XZB axes are controlled. However, in addition to the X axis swing (B axis), the Z axis may be swung, or other axis control may be added. .
Further, the numerical values of the abrasive grain size and speed used in the embodiments are all desirable examples, and the present invention is not limited thereto.

1 is a schematic view of an entire molding apparatus in Embodiment 1. FIG. It is a figure explaining the positional relationship of the cup type grindstone and the annular grindstone in Embodiment 1. FIG. It is a figure explaining the positional relationship of the contact point of the cup type grindstone and the annular grindstone in the shaping and sharpening process of the annular grindstone in Embodiment 1, (a) is a view seen from the Z-axis minus direction, (b) It is the figure seen from the Y-axis plus direction. It is a figure explaining the positional relationship of the contact of the cup type grindstone and the annular grindstone in Embodiment 2, and it is the figure seen from the Y-axis plus direction. It is a figure explaining the positional relationship of the contact point of the single stone diamond dresser and the annular grindstone in the molding process of the annular grindstone in Embodiment 3, (a) is a view seen from the Z-axis minus direction, (b) is Y It is the figure seen from the axis | shaft plus direction. It is a figure explaining the positional relationship of the contact point of a grindstone and a workpiece in nonpatent literature 1. It is a figure explaining the (a) shaping | molding process (b) sharpening process of the spherical shape grindstone in patent document 1. FIG. It is a figure explaining interfering with an aspherical surface work if a spherical shape grindstone is used. It is a figure explaining the means which shape | molds the processed surface of the grindstone in patent document 2 in a ring shape, (a) is a single stone diamond dresser method, (b) is a stainless roll method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Forming apparatus 2 Workpiece axis spindle 3 Z axis slide table 4 Cup type grindstone 5 X axis slide table 6 Grindstone axis spindle 7 B axis rotary table 8 Annular grindstone 9 Holding shaft 10 Slurry supply nozzle 11 GC slurry 12 Cup type GC grindstone 13 Single Stone Diamond Dresser 14 Dresser Fixing Tool 15 Screw 16 Grinding Wheel 17 Workpiece 18 Cup-shaped Grinding Wheel 19 Spherical Shaped Grindstone 20 Spherical Shaped Grindstone 22 Aspherical Workpiece 23 Single Ring Diamond Dresser 25 Single Stone Diamond Dresser 25 Stainless Roll 26 Molding Trace

Claims (8)

In the method of forming a grindstone for forming the annular grindstone by rotating an annular grindstone and a cup-type grindstone used to perform aspheric grinding on a molding device,
The cup-type grindstone that can be driven to rotate about the first rotation axis so that the molding surface of the cup-type grindstone is in contact with the annular grindstone at both ends of the diameter thereof intersects the first rotation axis. The ring-shaped grindstone that can be driven to rotate about two rotation axes, at least a direction in which they are separated from each other, a direction that intersects each other, and an angle of the second rotation axis of the ring-shaped grindstone with respect to the cup-shaped grindstone A method for forming a grindstone, comprising forming the annular grindstone by performing movement control for relative movement in a changing direction.   The movement control includes movement control of the cup-type grindstone in the first rotation axis direction, movement control of the annular grindstone in a direction orthogonal to the first rotation axis direction, and the annular grindstone. The method for forming a grindstone according to claim 1, further comprising: swing control of the second rotation shaft.   3. The method according to claim 1, wherein after forming the annular grindstone, it is conspicuous by interposing a slurry having GC (Green Silicon Carbide) abrasive grains on a contact surface between the annular grindstone and the cup-type grindstone. The method for forming a grindstone according to 1.   The method for molding a grindstone according to any one of claims 1 to 3, wherein the molding surface of the cup-type grindstone includes GC (Green Silicon Carbide) abrasive grains. In the method of forming a grindstone for forming the annular grindstone by rotating an annular grindstone and a diamond dresser used for performing aspheric grinding on a molding apparatus,
The diamond dresser that can be swiveled around the first rotation axis so that the forming surface of the diamond dresser is in contact with the annular grindstone at both ends of the swivel diameter, and the first rotation axis intersects The annular grindstone that can be driven to rotate about two rotation axes, at least a direction in which they are separated from each other, a direction that intersects each other, and an angle of the second rotation axis of the annular grindstone with respect to the diamond dresser A method for forming a grindstone, wherein the annular grindstone is formed by performing movement control for relative movement in a moving direction. In a grindstone forming apparatus for shaping the annular grindstone by rotating an annular grindstone used for performing aspheric grinding and a cup-type grindstone,
The cup-type grindstone that can be driven to rotate around the first rotating shaft and the annular grindstone that can be driven to rotate about the second rotating shaft that intersects the first rotating shaft, A moving means for relatively moving in a direction in which the second rotating shaft of the annular grindstone is changed with respect to the direction of separating and contacting, the direction intersecting with each other, and the cup-shaped grindstone;
Control means for controlling the amount of movement in each direction by the moving means so that the molding surface of the cup-type grindstone is in contact with the annular grindstone at both diameter ends;
An apparatus for forming a grindstone, comprising:   The moving means slides the cup-type grindstone in the direction of the first rotation axis, and slides the annular grindstone in a direction orthogonal to the first rotation axis direction. The grindstone forming apparatus according to claim 6, further comprising: 2 slide means and a rocking means for rocking the second rotation shaft of the annular grindstone.   8. The method according to claim 6, wherein after forming the annular grindstone, it is conspicuous by interposing a slurry having GC (Green Silicon Carbide) abrasive grains on a contact surface between the annular grindstone and the cup-type grindstone. The grindstone forming apparatus described in 1.