JP3304163B2 - Electrolytic in-process dressing grinding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic in-process dressing grinding apparatus which can prevent unevenness in dressing of a grinding tool in profile grinding of a workpiece such as a lens.

[0002]

2. Description of the Related Art Generally, grinding of a workpiece such as a lens is performed by rotating a grinding tool and swinging the workpiece with the grinding tool. However, there has been a problem that the grinding tool is clogged, the grinding ability is reduced, and grinding takes a long time. In order to solve the above problem, a method has been devised in which grinding is performed while electrolytically in-process dressing the processing surface of a grinding tool. As an apparatus for performing such a grinding method, for example, Japanese Patent Application Laid-Open No. HEI 5-16064 has been proposed. It is disclosed in the gazette.

FIG. 7 is a schematic configuration diagram showing the above-mentioned grinding apparatus. A grinding tool 2 having conductivity is integrally formed at the tip of a rotating shaft 1 connected to a driving device (not shown). The grinding tool 2 is formed by bonding abrasive grains of diamond powder or the like with a conductive bond, and the tip is formed on a hemispherical processing surface 3. The member to be processed (work) 4 is in contact therewith. The workpiece 4 is held by a holding plate 5.

A concave portion is formed in the center of the upper surface of the holding plate 5, and the concave portion has a substantially bar-shaped spherical core 6a having a spherical tip.
Is engaged. The upper end of the kansashi 6 is connected to a pressurizing device 7, which is connected to and held by a swing drive device 8. A ring-shaped electrode 9 surrounding the workpiece 4 is suspended from the outer peripheral wall of the holding plate 5, and the electrolytic surface 9 a of the electrode 9 has a slight gap 1 with the processing surface 3 of the grinding tool 2. Is provided.

A DC power supply 10 for generating a pulse voltage for electric discharge machining is provided near the holding plate 5. The (+) pole of the DC power supply 10 is a brush 1 that contacts the outer peripheral surface of the rotating shaft 1.
1 is connected to a grinding tool 2. The (−) pole of the DC power supply 10 is connected to the electrode 9 via the wrench 6 and the holding plate 5. The DC power supply 10 and the swing driving device 8 are connected to and controlled by a control device 12.

[0006] A pipe 13 connected to a water supply device (not shown) is provided near the electrode 9, and the electrode 9 and the grinding tool 2 are provided.
Is provided so that a coolant (cooling medium) 14 can be supplied to the gap 1 between the two.

When the workpiece 4 is ground by using the grinding apparatus having the above configuration, the driving of the holding plate 5 (oscillation center O) and the rotation of the grinding tool 2 are simultaneously performed, and the grinding tool 2 is rotated.
The coolant 14 is supplied to a gap 1 between the processed surface 3 of the electrode 9 and the electrolytic surface 9a of the electrode 9. Then, by the voltage applied to the grinding tool 2 and the electrode 9 by the DC power source 10, electrolysis is generated on the processing surface (abrasive surface) 3 of the grinding tool 2, and the entire processing surface of the grinding tool 2 is dressed. The swing in the grinding tool is performed by the control device 12, and the timing of the application of the voltage by the DC power supply 10 is also performed by the control device 12.

[0008]

However, in the above-mentioned conventional grinding apparatus, there is a problem that the electrolytic action is concentrated on the edge portion of the grinding tool 2 and the bond protrusion is promoted more than other portions. That is, as shown in the partial sectional view of the ring-shaped electrode 9 and the grinding tool 2 in FIG.
Since the coolant 14 also intervenes on the outer side of the point P of the electrode surface 9a on the extension of a, electrolysis occurs intensively between the electrolytic surface 9a and the etching portion 2b of the grinding tool 2 at the shortest distance, Dressing of the edge portion 2b is performed more than other portions in accordance with the amount of electrolysis. For this reason, there is a problem that bond elution occurs more than necessary at the edge portion 2b, the shape is broken from the outer periphery of the grinding tool 2, and the shape accuracy of the workpiece 4 is reduced accordingly. In addition, the removal of the abrasive grains is promoted by the bond elution, so that the grinding tool 2
There is a problem that the amount of the dropped abrasive grains interposed in the gap between the workpiece 4 and the workpiece 4 increases, and the workpiece 4 is scratched.

The present invention has been made in view of the above-mentioned problems of the prior art, and prevents the concentration of electrolysis at the edge of the grinding tool, maintains the shape of the grinding tool, and reduces the size of the dropped abrasive grains. It is an object of the present invention to provide an electrolytic in-process dressing grinding apparatus capable of performing grinding without causing scratches on a workpiece due to rolling.

[0010]

In order to achieve the above object, the present invention relates to a rotatable conductive grinding tool connected to an anode of a DC power supply, and a conductive grinding tool connected to a cathode of a DC power supply. In an electrolytic in-process dressing grinding apparatus for supplying a coolant between an electrode that can be arranged opposite to a processing surface of the conductive grinding tool and electrolytically dressing the processing surface, a metal powder or a metal powder is formed on a peripheral surface of the conductive grinding tool. A conductive layer made of a paste mixed with is provided.

[0011]

According to the above construction, while the voltage is applied between the electrode and the conductive grinding tool, the conductive grinding tool is rotated to electrolytically dress the work surface of the conductive grinding tool. At this time, the electrolysis concentrates on the metal or the conductive layer provided on the peripheral surface of the conductive grinding tool, and the elution of the metal or the conductive layer is promoted more than the above-mentioned processed surface. Electrolytic dressing of the processed surface is performed without concentration.

[0012]

Embodiment 1 First, before describing a specific embodiment of the present invention, an outline of the present invention will be described. The outline of the present invention is to provide a conductive grinding tool rotatably connected to the anode of the DC power supply, and to provide a ring-shaped electrode connected to the cathode of the DC power supply so as to be able to oppose the processing surface of the conductive grinding tool,
In an electrolytic in-process dressing grinding apparatus provided with a means for supplying a coolant between the conductive grinding tool and the electrode, a conductive layer made of a paste obtained by mixing metal or resin with metal powder on a peripheral surface of the conductive grinding tool. Was provided. According to the above configuration, the workpiece is relatively swung along the working surface of the conductive grinding tool, and the coolant is supplied between the working surface of the conductive grinding tool and the electrode (electrolytic surface). Grind the workpiece. And
When the electrolytic surface and the center of the processing surface overlap, the conductive grinding tool is rotated at least once while applying a voltage between the electrode and the conductive grinding tool to perform electrolytic dressing of the processing surface. At this time, electrolysis concentrates on the conductive layer provided on the peripheral surface of the conductive grinding tool, elution of the conductive layer is promoted from other portions (processed surface), and the processed surface is not concentrated on the edge portion of the conductive grinding tool. Electrolytic dressing of the entire surface is performed. Next, a specific embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a partial cross section of an electrolytic in-process dressing grinding device (hereinafter, referred to as a grinding device) according to a first embodiment of the present invention, and FIG. The grinding apparatus according to the present embodiment has a grinding tool 21 having conductivity and having an upper surface, that is, a processing surface 21a formed in a spherical shape.
Are integrally provided at the tip of the rotary shaft 22 connected to a drive source device (not shown). Rotary shaft 22, the center of curvature O ₁ of the processing surface 21a as a fulcrum mounted for spherical center swinging motion, and is rotatably held about the axis by the lower shaft base over scan 24 via a bearing 23.

Above the processing surface 21a of the grinding tool 21,
A holder 26 is provided for holding a workpiece 25 having a workpiece surface 25a having a shape corresponding to the workpiece surface 21a in a state where the workpiece surface 21a and the workpiece surface 25a are in contact with each other. The lower surface, which is a holding portion of the holder 26, is a work surface 25a.
And is formed in the same shape as the opposite side surface of the device to hold the opposite side surface. The holder 26 is held by the wrench 27 in a state where the tip spherical portion of the bar-shaped wrench 27 is engaged in a spherical recess formed at the center of the upper surface. The kansashi 27 is connected to a pressurizing device (not shown). As a result, the workpiece 21 is pressed by the wrench 27 via the holder 26 and swings on the processing surface 21a with the center of the upper surface of the holder 26 as a fulcrum.

A ring-shaped electrode 28 is fixed to the outer peripheral surface of the holder 26, and is provided such that its electrolytic surface 28a is opposed to the processing surface 21a of the grinding tool 21 through a predetermined gap in a non-contact manner. Have been. The cathode of the DC power supply 29 is connected to the Kansashi 27, and the electrode 28 is electrically connected to the cathode of the DC power supply 29 via the holder 26.

The anode of the DC power supply 29 is connected to the power supply brush 30, the terminal 31 and the guide 3
2 is electrically connected to the grinding tool 21 via the conductive portion 32a. The terminal 31 is fixed on the lower shaft base 24 at a position parallel to the rotation shaft 22, and is fixed to a tip end of an arm 33 that can swing around a spherical center in conjunction with the rotation shaft 22.

The guide 32 is fixed to a guide holding portion 34 of the apparatus main body so as to face the terminal 31. The guide 32 is provided with a conductive portion 32a connected to the anode of the DC power supply 29 and an insulating portion 32b.
Is disposed such that the terminal 31 is in contact when the position on the processing surface 21a at the center of rotation of the grinding tool 21 and the electrolytic surface 28a of the electrode 28 coincide with each other or are located in the vicinity thereof.

A copper alloy layer 35 is provided on the outer peripheral surface of the grinding tool 21.
Is formed, and is electrically connected to the anode of the DC power supply 29 via the grinding tool 21. In the figure, 36 is a grinding tool 2
The coolant nozzle supplies the coolant 37 to a gap between the first processing surface 21a and the electrolytic surface 28a of the electrode 28.

In the grinding apparatus having the above-described structure, the coolant 37 is supplied from the coolant nozzle 36, and the grinding tool 21 is rotated and oscillatingly moved to rotate the grinding tool 21. The work surface 25a is ground by the work surface 21a of the grinding tool 21. The terminal 31 fixed to the tip of the arm 33 swings around the center of curvature O ₁ of the processing surface 21 a in conjunction with the swing of the rotating shaft 22. During this swing, the terminal 3
Electric current flows only when 1 contacts the conductive portion 32a of the guide, and an electrolytic action occurs between the electrode 28, the grinding tool 21, and the copper alloy layer 35. When the terminal 31 and the conductive portion 32a come into contact with each other, the rotation center of the processing surface 21a and the electrolytic surface 28a coincide with or approach each other. Therefore, the entire processing surface 21a is electrolytically dressed.

At this time, since the outer peripheral surface of the grinding tool 21 is covered with the copper alloy layer 35, the electrolytic action is concentrated on the edge 35a of the copper alloy layer 35. For this reason, the elution of the copper alloy layer 35 is promoted, but the bond elution at the end face of the grinding tool 21 is at the same level as the other processing surface 21a, and the entire surface of the processing surface 21a is evenly electrolyzed.

According to this embodiment, since the electrolytic action is not concentrated on the end face of the grinding tool 21 and the electrolytic dressing of the entire surface of the processing surface 21a can be performed uniformly, the shape of the processing surface 21a can be maintained. The workpiece 25 can be machined with high precision, and the amount of the abrasive grains falling off can be reduced, so that it is possible to prevent the workpiece 25 from being scratched by the rolling of the abrasive grains. Further, even when the workpiece 21 contacts the copper alloy layer 35, the oxide serves as a cushion and does not scratch.

Similar effects can be obtained by using an aluminum alloy instead of a copper alloy. Further, the workpiece 21
Fine abrasive grains (diamond, cerium oxide, alumina) may be mixed into the alloy as a lubricant in order to reduce friction at the time of contact.

[0022]

[Embodiment 2] FIG. 3 is a schematic configuration diagram showing a second embodiment of the present invention in partial cross section. In the present embodiment, instead of the copper alloy 35 in the first embodiment, the point that the low melting point metal layer 40 is disposed on the outer peripheral surface of the grinding tool 21 and the workpiece 25 is changed from a concave shape to a convex shape, The difference is that the machining surface 21a of the grinding tool 21 is changed from a convex shape to a concave shape accordingly, and the other components are composed of the same components, and the same components are denoted by the same reference numerals and description thereof is omitted. I do. As the low melting point metal forming the low melting point metal layer 40, for example, a Bi-Sn based metal or a Zn based metal can be used.

In this embodiment, the concave processing surface 21a of the grinding tool 21 is brought into contact with the convex processing surface 25a of the workpiece 25, and the center of curvature O ₂ of the processing surface 21a is used as a fulcrum. The workpiece 25 is ground by swinging the heart in the same manner as in the first embodiment. At the time of this grinding, the electrode 28 is provided with the first embodiment.
Is applied at the same position as described above, and the electrolytic dressing of the processing surface 25a is performed. At this time, the electrolytic action is concentrated on the edge portion 40a of the low melting point metal layer 40 as in the first embodiment.

According to the present embodiment, as in the first embodiment, the shape of the grinding tool 21 can be prevented from collapsing. Further, since the low-melting metal layer 40 is softer than the metal bond (iron, bronze, nickel) of the grinding tool 21, it has a great effect in preventing scratches due to friction with the workpiece 25. In addition, since the low melting point metal can be sintered at a low temperature after the sintering of the grinding tool, it becomes easy in the production method. Note that fine abrasive grains (diamond, cerium oxide, alumina) may be mixed into the low melting point metal as a lubricant for reducing friction when the workpiece 25 contacts.

FIG. 4 is a sectional view showing a modification of the grinding tool according to the second embodiment. The grinding tool 21 of the modification is used when a hole 41 is provided at the center of the grinding tool 22 and grinding is performed while supplying coolant from the hole 41, and the inner peripheral surface of the hole 41 is similar to the outer peripheral surface. Low melting metal layer 4
0 is provided. For this reason, similarly to the outer peripheral surface, it is possible to prevent the shape of the central portion of the processing surface 21a from being deformed, and it is possible to prevent the generation of scratches on the workpiece by abrasive grains.

[0026]

Third Embodiment FIG. 5 is a schematic configuration diagram showing a third embodiment of the present invention in a partial cross section. This embodiment is different from the first embodiment in that the number of the workpieces 25 to be processed is changed from one to many, and a plurality of holders 51 are provided instead of the electrodes 28 and the holders 26. , Except that the silver paste 50 is provided on the outer peripheral surface of the grinding tool 21 in place of the copper alloy layer 35, and the other components are composed of the same components, and the same components are given the same numbers, The description is omitted.

The silver paste 50 provided on the outer peripheral surface of the grinding tool 21 is formed by mixing silver powder into epoxy resin to the extent that conductivity can be obtained. Also, a large number of workpieces 2
The multi-piece holder 51 for holding 5 is electrically connected to the cathode of the flow-through power supply 29 through the screwdriver 27 and is configured to also serve as the electrode 28 of the first embodiment.

In this embodiment, the electrolytic action concentrates on the edge 50a of the silver paste 50. Other operations are the same as those of the first embodiment.

According to the present embodiment, since the strength of the silver paste 50 is substantially equal to the resin strength, it is very soft and brittle, so that it has a great effect in preventing the occurrence of scratches due to friction with the workpiece 25. Further, it can be applied to a finished product of a normal metal bond grinding tool and bonded at about 150 degrees. Note that fine abrasive grains (diamond, cerium oxide, alumina) may be mixed into the silver paste 50 as a lubricant for reducing friction when the workpiece 25 contacts.

[0030]

Fourth Embodiment FIG. 6 is a schematic structural view showing a fourth embodiment of the present invention in a partial cross section. In this embodiment, the first embodiment is used.
Instead of the grinding tool 21 in the above, a large number of pellet grinding tools 61 are attached to an attaching jig 60, and the difference is that a copper alloy layer 62 is provided on each outer peripheral surface of the pellet grinding tools 61. The configuration is composed of the same components, and the same components are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, a large number of pellet grinding tools 61 held on a rotating shaft via an attaching jig 60
Is swung around the swing center O ₁ as a fulcrum, and the workpiece 25 is swung.
Grinding is performed. Then, when the electrode 28 coincides with or is located near the center of rotation on the surface of the bonding jig 60, the terminal 31 and the conductive portion 32a contact each other, and the processing surface of each pellet grinding tool 61 is the same as in the first embodiment. Electrolytic dressing. At this time, the electrolytic action concentrates on the edge portion 62a of the copper alloy layer 62, and the electrolytic dressing is performed as in the case of the single grinding tool 21 of the first embodiment.

According to the present embodiment, the same effect as in the first embodiment can be obtained by using a large number of pellet grinding tools 61 as the grinding tools.

[0033]

As described above, according to the electrolytic in-process dressing grinding apparatus of the present invention, the conductive layer is provided on the peripheral surface of the grinding tool, and the electrolytic action is applied to the conductive layer during the electrolytic dressing of the processing surface of the grinding tool. Since the concentration can be performed, it is possible to prevent the electrolysis from being concentrated on the edge portion of the grinding tool, and to perform a uniform electrolytic dressing on the entire surface of the processing surface. Thus, it is possible to perform the grinding while maintaining the shape of the grinding tool, preventing the removal of the excessive abrasive grains, and preventing the workpiece from being scratched by the rolling of the dropped abrasive grains.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention in a partial cross section.

FIG. 2 is a view taken in the direction of arrow A in FIG. 1;

FIG. 3 is a schematic configuration diagram showing a second embodiment of the present invention in a partial cross section.

FIG. 4 is a sectional view showing a modification of the grinding tool according to the second embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a third embodiment of the present invention in a partial cross section.

FIG. 6 is a schematic configuration diagram showing a fourth embodiment of the present invention in a partial cross section.

FIG. 7 is a schematic configuration diagram showing a conventional electrolytic in-process dressing grinding apparatus.

FIG. 8 is an explanatory diagram for describing a problem of a conventional electrolytic in-process dressing grinding device.

[Explanation of symbols]

 21 Grinding Tool 25 Workpiece 28 Electrode 29 DC Power 35,62 Copper Alloy Layer 40 Low Melting Metal Layer 50 Silver Paste 61 Pellet Grinding Tool

Claims (1)

(57) [Claims] 1. A coolant between a rotatable conductive grinding tool connected to an anode of a DC power supply and an electrode connected to a cathode of the DC power supply and capable of being arranged facing a processing surface of the conductive grinding tool. And an electrolytic in-process dressing grinding apparatus for electrolytically dressing the machined surface, wherein an electroconductive layer made of a paste obtained by mixing metal or resin with metal powder is provided on a peripheral surface of the electroconductive grinding tool. In-process dressing grinding device.