JP2010253593A - Recessed spherical surface grinding device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide recessed spherical surface grinding device and method capable of machining a deep recessed spherical surface closer to a semi-spherical surface, for instance, into a highly smooth and highly accurate recessed spherical surface with high efficiency. <P>SOLUTION: This recessed spherical surface grinding device includes a spherical tool 12 having a surface constituted of a conductive grinding tool 13, a prescribed diameter and roundness, a tool holding tool 14 for freely movably holding a lower part from a center of the spherical tool 12, a workpiece holding tool 18 for holding a workpiece having a semi-spherical upper recessed hole in contact with an upper part from the center of the spherical tool 12, a relative position adjusting device 20 for adjusting a relative position of the spherical tool 12 and the workpiece by moving the workpiece holding tool 18 or the tool holding tool 14, an ELID device 22 for performing electrolytic dressing for the surface of the spherical tool 12, and a random driving device 30 for driving the spherical tool 12 along the surface at random. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a concave spherical grinding apparatus and method for making a concave spherical surface surrounding a spherical surface highly smooth and highly accurate.

  The wear resistance of an artificial joint is an important factor that most affects the life of the artificial joint. However, under the present circumstances, since the life of the artificial joint is shorter than the remaining life of the patient due to wear and the patient is forced to perform reoperation, there is an urgent need to improve the wear resistance.

  FIG. 1 is a schematic diagram showing the structure of an artificial joint. A spherical bone head 51 is fixed to the stem 52, and a portion having a convex spherical surface of the bone head 51 contacts a concave spherical surface of the socket 53, thereby constituting a sliding surface of the joint. However, long-term relative sliding causes slack between the sliding surfaces, and this slack dominates the life of the artificial joint.

  In order to extend the life of the artificial joint, it is essential to optimize the material of the socket 53 and the bone head 51 and improve the surface roughness and shape accuracy. However, the conventional prosthetic joint material has a problem that its life is short because a combination of a polyethylene socket and a metal bone head is the mainstream.

  Accordingly, the inventors of the present invention have previously created and filed a patent document 1 as means for processing the spherical surface of the bone head 51. As processing means for the concave spherical surface of the socket 53, for example, Patent Documents 2 and 3 have already been disclosed.

Patent Document 1 aims to process a ceramic that is a hard and brittle material as compared with metal into a spherical surface that is smoother and more accurate than metal.
Therefore, in this processing method, as shown in FIG. 2, the grinding step (A) and the electrolytic dressing step (B) are performed alternately. In the grinding step (A), the workpiece 61 having the spherical surface 61a is driven to rotate about a rotation axis z passing through the center O and orthogonal to the horizontal axis y while swinging the workpiece 61 about the horizontal axis y passing through the center O of the spherical surface. At the same time, a conductive grindstone 64 having a concave spherical surface 64a fitted to the spherical surface 61a of the workpiece is supported so as to be swingable along the spherical surface 61a of the workpiece, a constant load is applied toward the workpiece, and the concave spherical surface 64a The workpiece is ground by rotating around a vertical axis passing through the center. In the electrolytic dressing step (B), the conductive grindstone 64 is rotationally driven about a vertical axis passing through the center of the concave spherical surface 64a, and a certain gap is provided between the conductive grindstone 64a and the concave spherical surface 64a to position the cathode 67. The concave spherical surface 64a is electrolytically dressed.

Patent Document 2 aims at a spherical machining apparatus that does not require tool position adjustment due to grinding wheel wear.
Therefore, as shown in FIG. 3, in this apparatus, a total type grindstone 71 for grinding and polishing a workpiece W such as a lens having a spherical surface is attached to the lower end of a tool shaft 72 which is an upper shaft that is held vertically and rotated. And pressed against the workpiece W by the air cylinder 73. The workpiece W is held by a workpiece shaft 75 which is a lower shaft via a spacer 74, and the workpiece W and the grinding stone 71 are slid by the swinging of the inclined workpiece shaft 75 and the accompanying rotation by the rotating grinding stone 71. It is.

Patent Document 3 aims to improve machining efficiency and shorten machining time in the grinding of an axisymmetric aspherical shape in which the workpiece surface of the workpiece to be ground is an arbitrary shape regardless of whether it is concave or convex. And
For this reason, as shown in FIG. 4, the ultraprecision machining apparatus moves the tool grindstone 87 relative to the workpiece surface of the workpiece 88 that is being rotated to move the tool grindstone 87 while rotating it. Grind. Here, as the tool grindstone 87, a cylindrical shape having a circular cross-sectional shape at the tip is used, and the cylindrical shape which is the rotation axis of the workpiece 88 and the rotation axis of the tool grindstone 87 is used. Grinding is performed by relatively moving the workpiece 88 and the tool grindstone 87 while controlling the angle formed with the central axis based on the radius of curvature in the diameter direction at the processing point of the workpiece 88 to be ground. Is.

Japanese Patent Application Laid-Open No. 2002-263959, “Spherical grinding method and apparatus” JP 2005-14168, “Spherical surface processing apparatus” JP 2008-68337 A, “Grinding Method and Grinding Device”

  In Patent Document 1 described above, spherical processing with a surface roughness of 4 nmRa and a roundness of 0.5 μm is realized for ceramics. In addition, by applying this means to a metal material, spherical processing with high smoothness and high accuracy can be similarly performed. However, this method has a problem that the concave spherical surface of the socket cannot be processed.

Since patent document 2 uses the grindstone 71 of a total type, there exists the characteristic which can process the concave spherical surface fitted with the grinding surface of the grindstone 71. FIG. However, when the concave spherical surface of the workpiece (workpiece) is deep (for example, close to a hemispherical surface), the grinding speed varies greatly between the vicinity of the center of rotation of the grindstone 71 and the vicinity of the outer periphery, so there is a variation in surface roughness and roundness. As a result, the entire inner surface of the concave spherical surface could not be processed with high smoothness and high accuracy.
Further, in this apparatus, it is difficult to electrolytically dress the grinding surface of the grindstone 71 during the grinding process, and the grindstone 71 is likely to be clogged, resulting in low machining efficiency (efficiency).

Patent Document 3 has a feature that an arbitrary shape of an axisymmetric concave spherical surface and concave aspherical surface can be processed. However, if the workpiece (workpiece) has a deep concave spherical surface (for example, close to a hemispherical surface), it is indispensable to downsize the tool or extend the shank. There were problems such as vibration.
Further, with this apparatus, it is difficult to perform electrolytic dressing on the grinding surface of the tool grindstone 87 during grinding, and the tool grindstone 87 is likely to be clogged, resulting in low machining efficiency (efficiency).

  The present invention has been developed to solve the above-described problems. That is, an object of the present invention is to provide a concave spherical grinding apparatus and method capable of processing, for example, a deep concave spherical surface close to a hemispherical surface into a highly smooth concave surface with high accuracy and high efficiency.

According to the present invention, a spherical tool whose surface is made of a conductive grindstone and has a predetermined diameter and roundness,
A tool holder that holds a portion below the center of the spherical tool in a freely movable manner;
A random driving device that randomly drives the spherical tool along its surface;
A workpiece holder for holding a workpiece having a hemispherical upper concave hole that comes into contact with an upper portion of the spherical tool;
A relative position adjustment device that moves the workpiece holder or the tool holder to adjust the relative position of the spherical tool and the workpiece;
There is provided an ELID device that electrolytically dresses the surface of the spherical tool.

According to a preferred embodiment of the present invention, the spherical tool has recesses arranged dispersed on the surface thereof,
The random driving device includes two or more liquid injection nozzles arranged in different directions with respect to the concave portion, and a random injection device that randomly injects a predetermined liquid through the two or more liquid injection nozzles.

According to another embodiment of the present invention, the spherical tool has a ferromagnetic body at a position offset from the center,
The random driving device includes two or more magnetic field generating coils that apply magnetic fields in different directions to the ferromagnetic material, and a random power supply device that randomly supplies power to the two or more magnetic field generating coils.

According to another embodiment of the present invention, the spherical tool has a permanent magnet having an NS pole inside,
The random drive device includes two or more magnetic field generating coils that apply a rotational force to the permanent magnet in different directions, and a random power supply device that randomly supplies power to the two or more magnetic field generating coils.

  According to another embodiment of the present invention, the random driving device includes two or more rotational driving rollers that contact the surface of the spherical tool and rotationally drive the spherical tool in different directions, and power to the two or more rotational driving rollers. And a random power supply device that randomly supplies power.

  According to another embodiment of the present invention, the random drive device includes a magnet for attracting the spherical tool to a tool holder by a magnetic force, and a rotation drive device that rotationally drives the tool holder about a vertical axis. And a random power supply device that randomly changes the power supplied to the rotary drive device.

In addition, the tool holder has a lower recessed hole that surrounds a lower part closer to the center of the spherical tool,
A conductive liquid supply device for supplying a conductive liquid to the surface of the lower concave hole is provided.

  The ELID device applies an ELID cathode facing a part of a spherical tool with a certain gap, an anode brush contacting another part of the spherical tool, the spherical tool plus through the anode brush, and And an ELID power supply device for applying the ELID cathode to the negative.

Further, according to the present invention, the lower portion of the surface of the spherical tool having a predetermined diameter and roundness made of a conductive grindstone is held free to move,
Driving the spherical tool randomly along its surface;
Holding a work having a hemispherical upper concave hole that comes into contact with the upper part of the center of the spherical tool;
There is provided a concave spherical grinding method characterized by adjusting the relative position of the spherical tool and the workpiece and grinding the upper concave hole of the workpiece with the spherical tool while electrolytically dressing the surface of the spherical tool. The

  According to the method and apparatus of the present invention described above, the spherical tool has a predetermined diameter and roundness, the lower part is held free from the center of the spherical tool by the tool holder, and the spherical tool is Since it is driven randomly along the surface, the concave spherical surface of the workpiece is deep, for example close to a hemispherical surface, by adjusting the relative position of the spherical tool and the workpiece and grinding the upper concave hole of the workpiece with the spherical tool However, the contact speed (that is, the grinding speed) with the spherical tool is the same in the vicinity of the center and the outer periphery of the upper concave hole of the workpiece, and the surface roughness and roundness of the concave spherical surface can be made uniform.

In addition, since the surface of the spherical tool is made of a conductive grindstone, the upper concave hole of the workpiece is ground with the spherical tool while electrolytically dressing the surface of the spherical tool with an ELID device. It can be processed with high accuracy.

It is a schematic diagram which shows the structure of an artificial joint. It is a schematic diagram which shows the processing method of patent document 1. FIG. It is a schematic diagram of the spherical surface processing apparatus of patent document 2. FIG. It is a schematic diagram of the processing apparatus of patent document 3. It is a 1st embodiment figure of a concave spherical grinding device of the present invention. It is 2nd Embodiment figure of the concave spherical surface grinding apparatus of this invention. It is 3rd Embodiment figure of the concave spherical surface grinding apparatus of this invention. It is 4th Embodiment figure of the concave spherical surface grinding apparatus of this invention. It is 5th Embodiment figure of the concave spherical surface grinding apparatus of this invention. It is 6th Embodiment figure of the concave spherical surface grinding apparatus of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

FIG. 5 is a first embodiment of the concave spherical grinding apparatus of the present invention.
In this figure, the concave spherical grinding apparatus of the present invention includes a spherical tool 12, a tool holder 14, a work holder 18, a relative position adjusting device 20, an ELID device 22, and a random driving device 30.

  A workpiece 10 to which the present invention is applied is, for example, a socket illustrated in FIG. The material of the workpiece 10 is preferably a metal having high wear resistance, corrosion resistance, toughness, biocompatibility and hardness (for example, a Co—Cr alloy), but other metals or ceramics which are hard and brittle materials. There may be.

The surface of the spherical tool 12 is made of a conductive grindstone 13 and has a predetermined diameter and roundness.
The spherical tool 12 has a spherical surface that fits into the concave spherical surface of the socket illustrated in FIG.
The conductive grindstone 13 is a metal bond grindstone, and a composite bond material in which a metal (for example, cast iron, copper) and a resin are mixed is used as the bond material. The abrasive grains are preferably diamond abrasive grains or CBN. The grain size of the abrasive grains is, for example, # 4000, # 8000, # 40000, # 120,000 (average grain sizes of 4.1, 1.8, 0.3, 0.13 μm) should be used.
The spherical tool 12 is not limited to a perfect spherical shape, and may be an aspherical shape.

The tool holder 14 holds a portion below the center of the spherical tool 12 so as to be freely movable.
Further, the tool holder 14 has a lower concave hole 14 a that surrounds a lower part closer to the center of the spherical tool 12. The inner surface of the lower concave hole 14a is a spherical surface that is slightly larger than the spherical tool 12, and the conductive liquid for electrolytic grinding flows through the gap, and the spherical tool 12 is floated by hydraulic pressure, so that the spherical tool 12 is almost non-resistance. And you can move freely.

  In FIG. 5, the concave spherical grinding apparatus of the present invention further includes a conductive liquid supply device 24 for supplying a conductive liquid to the surface of the lower concave hole 14a. The conductive liquid supply device 24 is installed outside the tool holder 14, and supplies the conductive liquid to the surface of the lower concave hole 14 a through a liquid flow path 24 a provided in the tool holder 14. The path and number of the liquid flow paths 24a are arbitrary.

In this example, the tool holder 14 has a magnet 16 that attracts the spherical tool 12 to the tool holder 14 with a magnetic force. The magnet 16 may be single or plural.
The magnet 16 attracts the spherical tool 12 to the tool holder 14 by magnetic force, and is sufficiently smaller than the roundness error of the upper concave hole 10a required for the workpiece 10, and the center position of the spherical tool 12 is within the error. Always hold.
The magnetic strength of the magnet 16 is arbitrary as long as the spherical tool 12 can move freely with almost no resistance. For example, when the amount of liquid ejected by the random ejection device 32 (described later) is large, or when the tool holder 14 is directed downward, the magnetic strength of the magnet 16 should be increased.

With the above-described configuration, the gap between the lower concave hole 14a and the spherical tool 12 is sufficiently smaller than the roundness error of the upper concave hole 10a required for the workpiece 10, and the center position of the spherical tool 12 is within the error. It always comes to hold.
In the present invention, the magnet 16 is not essential and can be omitted as long as the center position of the spherical tool 12 can always be held within the above error.

  The workpiece holder 18 holds the workpiece 10. In this example, the workpiece holder 18 grips the upper end of the workpiece 10, but the present invention is not limited to this, as long as the workpiece 10 can be gripped and moved integrally.

The relative position adjusting device 20 is, for example, a three-dimensional moving device, and moves the workpiece holder 18 or the tool holder 14 to adjust the relative position between the spherical tool 12 and the workpiece 10.
The relative position adjusting device 20 also has a mechanism that can pressurize with a constant pressure.
In this example, the tool holder 14 is fixed at a fixed position, and the work holder 18 is moved up and down (in the z-axis direction of the xyz axis) by the relative position adjusting device 20.
In addition, this invention is not limited to this, The workpiece holder 18 may be fixed to a fixed position, and the tool holder 14 may be moved. Further, the movement of the work holder 18 or the tool holder 14 is not limited to the vertical movement, and may move two-dimensionally or three-dimensionally.

  The ELID device 22 includes an ELID cathode 22a, an anode brush 22b, and an ELID power supply device 22c, and electrolytically dresses the surface of the spherical tool 12.

The ELID cathode 22a faces a part of the spherical tool 12 with a certain gap.
In this example, the ELID cathode 22a is an arc-shaped ring member positioned with a gap between the workpiece 10 and the workpiece holder 18, and the inner surface of the ELID cathode 22a is always set to maintain a constant gap with the outer surface of the spherical tool 12. Has been. This gap is set within a range in which the surface of the spherical tool 12 can be electrolytically dressed while flowing a conductive liquid in the meantime.
In addition, the installation position of the ELID cathode 22a is not limited to this example, and may be installed inside the work holder 18, for example.

The anode brush 22 b contacts another part of the spherical tool 12. In this example, the ELID cathode 22 a is positioned between the workpiece 10 and the workpiece holder 18 and contacts a part of the spherical tool 12. The position of the anode brush 22b may be as far as possible from the ELID cathode 22a, for example, in this example, on the opposite side of the ELID cathode 22a with the spherical tool 12 interposed therebetween.
Further, the contact between the anode brush 22b and the spherical tool 12 is made as small as possible so that the spherical tool 12 can be freely moved with almost no resistance as long as the spherical tool 12 can be applied positively via the anode brush 22b. It has become. For example, it is possible to provide a conductive hair made of conductive fibers on a part of the anode brush 22b, and to supply an electric current to the conductive bond material through this touch.
In addition, the installation position of the anode brush 22b is not limited to this example, For example, you may install in the inside of the workpiece | work holder 18. FIG.

  The ELID power supply 22c applies the spherical tool 12 to the plus (+) via the anode brush 22b, and applies the ELID cathode 22a to the minus (−). The applied power source may be a direct current power source or a direct current pulse power source as long as a desired electrolytic dressing is possible.

  The random drive device 30 drives the spherical tool 12 at random along the surface thereof. A specific example of the random drive device 30 will be described later.

Using the apparatus described above, in the method of the present invention,
(A) Using the workpiece holder 18, the surface is composed of the conductive grindstone 13, and the lower part of the center of the spherical tool 12 having a predetermined diameter and roundness is held movably,
(B) Random drive device 30 drives spherical tool 12 randomly along its surface;
(C) The workpiece 10 having the hemispherical upper concave hole 10a that is in contact with the upper part of the spherical tool 12 is held by the workpiece holder 18;
(D) The relative position of the spherical tool 12 and the workpiece 10 is adjusted by the relative position adjusting device 20, and the surface of the spherical tool 12 is electrolytically dressed by the ELID device 22. To grind.

  According to the above-described method and apparatus of the present invention, the spherical tool 12 has a predetermined diameter and roundness, and the tool holder 14 holds the portion below the center of the spherical tool 12 so as to be freely movable. 30, the spherical tool 12 is randomly driven along the surface thereof, so that the relative position between the spherical tool 12 and the workpiece 10 is adjusted, and the upper concave hole 10 a of the workpiece 10 is ground by the spherical tool 12. Even when the concave spherical surface is deep, for example, close to a hemispherical surface, the contact speed (that is, the grinding speed) with the spherical tool 12 is the same in the vicinity of the center of the upper concave hole 10a and the vicinity of the outer periphery of the workpiece 10, and the surface of the concave spherical surface 10a Roughness and roundness can be made uniform.

  Further, since the surface of the spherical tool 12 is made of the conductive grindstone 13, the upper concave hole 10a of the workpiece 10 can be ground with the spherical tool 12 while electrolytically dressing the surface of the spherical tool 12 with the ELID device 22.

FIG. 6 is a second embodiment of the concave spherical grinding apparatus of the present invention.
In this example, the spherical tool 12 has concave portions 12a arranged on the surface thereof.
In addition, the random drive device 30 includes two or more liquid injection nozzles 31 arranged in different directions with respect to the concave portion 12 a of the spherical tool 12, and a random injection that randomly injects a predetermined liquid via the two or more liquid injection nozzles 31. And an injection device 32.

The recess 12a of the spherical tool 12 is, for example, an arc-shaped recess, and receives the spray pressure of the liquid to drive the spherical tool 12 along the surface. The shape, size, number, and dispersion state of the recesses 12a are arbitrary.
The formation of the recess 12a is not essential, and may be a recess that is normally present on the surface of the conductive grindstone 13 made of abrasive grains and a bonding material as long as the spherical tool 12 can be driven along the surface.

  The liquid sprayed from the liquid spray nozzle 31 is preferably the above-described conductive liquid for electrolytic grinding. In this case, the above-described conductive liquid supply device 24 can be omitted.

The liquid sprayed by the random spray device 32 is not limited to the electroconductive liquid for electrolytic grinding, but may be other liquids such as tap water or distilled water. In this case, the amount of liquid injected by the random injection device 32 does not impair the function of the conductive liquid from the conductive liquid supply device 24, and the gap between the lower recessed hole 14a and the spherical tool 12 is always within the above-described range. Set to hold.
Other configurations are the same as those in FIG.

  With the above-described configuration, the spherical tool 12 is floated by hydraulic pressure, and in a state where the spherical tool 12 is free to move freely with almost no resistance, the liquid is randomly ejected through the two or more liquid ejecting nozzles 31 to form a spherical shape. The tool 12 can be driven randomly along its surface.

FIG. 7 is a diagram showing a third embodiment of the concave spherical grinding apparatus of the present invention.
In this example, the spherical tool 12 has a ferromagnetic body 12b (for example, an iron ball) at a position offset from the center.
The random drive device 30 includes two or more magnetic field generation coils 33 that apply magnetic fields in different directions to the ferromagnetic body 12b of the spherical tool 12, and a random power supply device that randomly supplies power to the two or more magnetic field generation coils 33. 34.
Other configurations are the same as those in FIG.

  With this configuration, power is randomly supplied to the two or more magnetic field generating coils 33 in a state in which the spherical tool 12 is almost free of resistance and freely moves, and randomly in different directions with respect to the ferromagnetic body 12b of the spherical tool 12. By applying a large magnetic field, the spherical tool 12 can be driven randomly along its surface.

FIG. 8 is a diagram of a fourth embodiment of the concave spherical grinding apparatus of the present invention.
In this example, the spherical tool 12 has a permanent magnet 12c having an NS pole inside. The number of permanent magnets 12c is not limited to a single number, and may be a plurality. Moreover, it is not limited to a center position, You may offset from a center.
The random drive device 30 includes two or more magnetic field generating coils 35 that apply rotational force to the permanent magnet 12c in different directions, and a random power supply device 34 that randomly supplies power to the two or more magnetic field generating coils. .
Other configurations are the same as those in FIG.

  With this configuration, when the spherical tool 12 is almost free of resistance and freely moves, power is randomly supplied to the two or more magnetic field generating coils 35, and randomly increased in different directions with respect to the permanent magnet 12 c of the spherical tool 12. By applying this rotational force, the spherical tool 12 can be randomly driven along its surface.

FIG. 9 is a fifth embodiment of the concave spherical grinding apparatus of the present invention.
In this example, the random driving device 30 is in contact with the surface of the spherical tool 12 and rotationally drives the spherical tool 12 in different directions, and a random power source that randomly supplies power to the two or more rotational driving rollers 36. Device 34.
In the case of this example, it is preferable to provide the above-described magnet 16 (not shown) and press the spherical tool 12 against the rotation drive roller 36 to reduce slip therebetween.
Other configurations are the same as those in FIG.

  With this configuration, power is randomly supplied to two or more drive rollers 36, and the surface of the spherical tool 12 is randomly rotated in different directions by the drive roller 36, so that the spherical tool 12 is randomly aligned along the surface. Can be driven.

FIG. 10 is a diagram of a sixth embodiment of the concave spherical grinding apparatus of the present invention.
In this example, the random drive device 30 includes a magnet 16 that attracts the spherical tool 12 to the tool holder 14 with a magnetic force, a rotation drive device 37 that rotates the tool holder 14 around a vertical axis, and a rotation drive device 37. And a random power supply device 34 that randomly changes the power supplied to the device.
In the case of this example, the magnet 16 is preferably set so that the frictional force between the spherical tool 12 and the tool holder 14 is increased and the spherical tool 12 can be rotated by the rotation of the tool holder 14.
Other configurations are the same as those in FIG.

  With this configuration, the spherical tool 12 can be randomly driven along its surface by inertia by randomly accelerating, decelerating, and reversing the rotational speed of the tool holder 14.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously, unless it deviates from the summary of this invention.

10 Workpiece, 10a Upper concave hole,
12 spherical tool, 12a recess, 12b ferromagnet,
12c permanent magnet, 13 conductive grindstone,
14 Tool holder, 14a Lower concave hole,
16 magnets, 18 workpiece holders,
20 relative position adjustment device, 22 ELID device,
22a ELID cathode, 22b anode brush,
22c ELID power supply,
24 conductive liquid supply device, 24a liquid flow path,
30 Random drive device, 31 Liquid injection nozzle,
32 random injection device, 33 magnetic field generating coil,
34 Random power supply, 36 Rotation drive roller,
37 Rotation drive

Claims (9)

A spherical tool whose surface is made of a conductive grindstone and has a predetermined diameter and roundness;
A tool holder that holds a portion below the center of the spherical tool in a freely movable manner;
A random driving device that randomly drives the spherical tool along its surface;
A workpiece holder for holding a workpiece having a hemispherical upper concave hole that comes into contact with an upper portion of the spherical tool;
A relative position adjustment device that moves the workpiece holder or the tool holder to adjust the relative position of the spherical tool and the workpiece;
A concave spherical grinding machine comprising: an ELID device for electrolytically dressing a surface of the spherical tool. The spherical tool has concave portions arranged dispersed on the surface thereof,
The random drive device includes two or more liquid injection nozzles arranged in different directions with respect to the concave portion, and a random injection device that randomly injects a predetermined liquid through the two or more liquid injection nozzles. The concave spherical grinding apparatus according to claim 1. The spherical tool has a ferromagnetic body at a position offset from the center,
The random drive device includes two or more magnetic field generation coils that apply magnetic fields in different directions to the ferromagnetic material, and a random power supply device that randomly supplies power to the two or more magnetic field generation coils. The concave spherical grinding apparatus according to claim 1, wherein the apparatus is a concave spherical grinding apparatus. The spherical tool has a permanent magnet having an NS pole inside,
The random drive device includes two or more magnetic field generating coils that apply rotational force to the permanent magnet in different directions, and a random power supply device that randomly supplies power to the two or more magnetic field generating coils. The concave spherical grinding apparatus according to claim 1, wherein the apparatus is a concave spherical grinding apparatus.   The random drive device has two or more rotational drive rollers that contact the surface of the spherical tool and rotationally drive them in different directions, and a random power supply device that randomly supplies power to the two or more rotational drive rollers. The concave spherical grinding apparatus according to claim 1, wherein:   The random drive device includes a magnet that attracts the spherical tool to a tool holder with a magnetic force, a rotary drive device that rotationally drives the tool holder around a vertical axis, and power supplied to the rotary drive device at random. The concave spherical grinding apparatus according to claim 1, further comprising a random power supply device to be changed. The tool holder has a lower recessed hole that surrounds a lower part closer to the center of the spherical tool,
The concave spherical grinding apparatus according to claim 1, further comprising a conductive liquid supply device that supplies a conductive liquid to a surface of the lower concave hole.   The ELID device applies an ELID cathode facing a part of a spherical tool with a certain gap, an anode brush contacting another part of the spherical tool, the spherical tool plus through the anode brush, and 2. The concave spherical grinding apparatus according to claim 1, further comprising an ELID power supply device that applies the ELID cathode to minus. The surface is made of a conductive grindstone, and the lower part of the spherical tool having a predetermined diameter and roundness is held in a freely movable manner,
Driving the spherical tool randomly along its surface;
Holding a work having a hemispherical upper concave hole that comes into contact with the upper part of the center of the spherical tool;
A concave spherical grinding method comprising: adjusting a relative position between the spherical tool and the workpiece, and grinding an upper concave hole of the workpiece with the spherical tool while electrolytically dressing a surface of the spherical tool.

Images