JPH06297314A - Electrolytic in-process dressing grinding device - Google Patents

Abstract

PURPOSE:To enable uniform electrolytic dressing, in the case where grinding is carried out by arranging a ring-shaped electrode so as to face the working surface of a conductive grinding tool and while supplying coolant therebetween, by providing a conductive layer on the circumferential surface of the grinding tool. CONSTITUTION:A grinding tool 21 is integrally provided to the end of a turning haft 22 that has been supported so as to be oscillatable making a fulcrum of he center O1 of curvature of a working surface 21a, and a work 25 to be worked hat has a surface 25a whose shape corresponds to that of the working surface 21a is arranged above the working surface 21a of the grinding tool 21, while being held by a holder 26. On the outer circumferential surface of the holder 26, a ring-shaped electrode 28 that has been connected to the negative electrode of a d.c. power supply 29 is fixed, and also the negative electrode of the d.c. power supply 29 is connected to a pivot pin 27 for oscillatably holding the holder 26. On the outer circumferential surface of the grinding tool 21, a copper alloy layer 35 as a conductive layer that is connected to the positive electrode of the d.c. power supply 29 is formed. Thereby, electrolytic dressing can be uniformly carried out all over the working surface 21a without concentrating the electrolytic action on the end surface of the grinding tool 21.

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 capable of preventing unevenness in dressing of a grinding tool in copy 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 the grinding tool and swinging the workpiece with the grinding tool. However, there is a problem in that the grinding tool is clogged and the grinding ability is reduced, which requires a long time for grinding. Therefore, in order to solve the above problem, a method of performing grinding while electrolytically in-process dressing the processed surface of the grinding tool has been devised, and an apparatus for carrying out such a grinding method is, for example, JP-A-5-16064. It is disclosed in the official gazette.

FIG. 7 is a schematic configuration diagram showing the grinding device, in which a grinding tool 2 having conductivity is integrally formed at the tip of a rotary shaft 1 connected to a driving device (not shown). The grinding tool 2 is composed of abrasive grains such as diamond powder bonded by a conductive bond, and the tip of the grinding tool 2 is formed on a hemispherical processed surface 3. The processed surface 3 has a corresponding processed surface. The member to be processed (work) 4 that has been held is in contact. The workpiece 4 is held by the holding tray 4 and the holding tray 5.

A concave portion is formed in the central portion of the upper surface of the holding plate 5, and the concave portion has a substantially rod-shaped spherical center 6a.
The kanzashi 6 which has is engaged. The upper end of the kanzashi 6 is connected to the pressurizing device 7, and the pressurizing device 7 is connected to and held by the swing drive device 8. A ring-shaped electrode 9 surrounding the workpiece 4 is vertically provided on the outer peripheral wall of the holding dish 5, and the electrolytic surface 9a of the electrode 9 has a slight gap 1 with the processed surface 3 of the grinding tool 2. It is provided.

A current source 10 for generating a pulse voltage for electric discharge machining is installed near the holding plate 5. The (+) pole of the DC power supply 10 contacts the outer peripheral surface of the rotating shaft 1
It is connected to the grinding tool 2 via 1. Further, the (−) pole of the DC power source 10 is connected to the electrode 9 via the coax 6 and the holding plate 5. The DC power source 10 and the swing drive device 8 are connected to a control device 12 and controlled.

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.
The coolant (cooling medium) 14 can be supplied to the gap 1 between

When the workpiece 4 is ground by using the grinding apparatus having the above-described structure, the grinding tool 2 is simultaneously driven to swing the holding tray 4 (swing center O) and the grinding tool 2 is rotated.
The coolant 14 is supplied to the gap 1 between the processed surface 3 and the electrolytic surface 9a of the electrode 9. Then, the voltage applied to the grinding tool 2 and the electrode 9 by the DC power supply 10 causes electrolysis on the machined surface (abrasive grain surface) 3 of the grinding tool 2 to dress the entire machined surface of the grinding tool 2. The swing in the grinding tool is performed by the control device 12, and the timing of voltage application 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 is also present outside the point P of the electrode surface 9a on the extension of a, electrolysis is intensively generated between the electrolytic surface 9a and the etching portion 2b of the grinding tool 2 which is the shortest distance, Depending on the amount of electrolysis, the edge portion 2b is dressed more often than the other portions. Therefore, bond elution occurs more than necessary at the edge portion 2b, and the shape of the grinding tool 2 collapses from the outer periphery of the grinding tool 2, resulting in a problem that the shape accuracy of the workpiece 4 is reduced. Further, since the removal of the abrasive grains is promoted by the bond elution, the grinding tool 2
There is a problem in that the amount of abrasive grains that have fallen in the gap between the workpiece 4 and the workpiece 4 increases, and the workpiece 4 is damaged.

The present invention has been made in view of the above-mentioned problems of the prior art. It prevents the concentration of electrolysis on the edge portion of the grinding tool, maintains the shape of the grinding tool, and removes the abrasive grains that have fallen off. An object of the present invention is to provide an electrolytic in-process dressing grinding device capable of performing grinding without causing scratches on a member to be processed due to rolling.

[0010]

In order to achieve the above object, the present invention provides a ring-shaped electrode rotatably provided with a conductive grinding tool connected to an anode of a DC power source and connected to a cathode of the DC power source. In the electrolytic in-process dressing grinding device, which is provided so as to be opposed to the processed surface of the conductive grinding tool and has means for supplying a coolant between the conductive grinding tool and the electrode, the peripheral surface of the conductive grinding tool And a conductive layer made of a paste in which metal powder is mixed with metal or resin.

[0011]

According to the above structure, the member to be machined is relatively swung along the machining surface of the conductive grinding tool, and the coolant is provided between the machining surface of the conductive grinding tool and the electrode (electrolytic surface). The workpiece is ground while being supplied. Then, when the electrolytic surface and the center of the processed surface overlap, the conductive grinding tool is rotated at least once while applying a voltage between the electrode and the conductive grinding tool, and the electrolytic dressing of the processed surface is performed. To do. At this time, electrolysis is concentrated on the conductive layer provided on the peripheral surface of the conductive grinding tool, elution of the conductive layer is promoted from other parts (processing surface), and the processing surface is not concentrated on the edge part of the conductive grinding tool. Electrolytic dressing of the entire surface is performed.

[0012]

[Embodiment 1] FIG. 1 is a schematic configuration diagram showing a partial cross section of an electrolytic in-process dressing grinding apparatus (hereinafter referred to as a grinding apparatus) of Embodiment 1 of the present invention, and FIG. It is a figure. In the grinding apparatus of the present embodiment, the grinding tool 21 having conductivity and having the upper surface, that is, the processing surface 21a formed in a spherical shape, is integrated with the tip of the rotary shaft 22 connected to a drive source device (not shown). Is provided for the purpose. Rotating shaft 22
Is provided so as to swing freely about the center of curvature O ₁ of the machined surface 21 a as a fulcrum, and through the bearing 23, the lower shaft base 2
It is held by 4 so as to be rotatable about its axis.

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 the holding portion of the holding tool 26, has a processed surface 25a.
It is formed in the same shape as the opposite side surface and holds this opposite side surface. The holder 26 is held by the hammer 27 in a state where a tip spherical portion of a rod-shaped hammer 27 is engaged in a spherical recess formed in the center of the upper surface of the holder 26. The connector 27 is connected to a pressurizing device (not shown). As a result, the member to be processed 21 is pressed by the hammer 27 via the holder 26 and is swung on the processed 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 its electrolytic surface 28a is provided so as to face the processing surface 21a of the grinding tool 21 in a non-contact manner with a predetermined gap. Has been. The cathode of the direct current 29 is connected to the contact 27, and the electrode 28 is electrically connected to the cathode of the direct current 29 through the holder 26.

The anode of the DC power supply 29 is in contact with the outer peripheral surface of the rotary shaft 22, and the power supply brush 30, the terminal 31, and the guide 3 are provided.
It is electrically connected to the grinding tool 21 through the conductive portion 32a arranged in the second section. The terminal 31 is fixed on the lower shaft base 24 at a position parallel to the rotating shaft 22, and is fixed to the tip end of an arm 33 that is swingable about the center of the ball in conjunction with the rotating shaft 22.

The guide 26 is fixed to the 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 arranged so as to come into contact with the terminal 31 when the position on the processed surface 21a at the center of rotation of the grinding tool 21 and the electrolytic surface 28a of the electrode 28 are located at or near the same.

A copper alloy layer 35 is formed 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 the grinding tool 2
This is a coolant nozzle that supplies the coolant 37 to the gap between the first processed surface 21a and the electrolytic surface 28a of the electrode 28.

In the grinding apparatus having the above structure, the coolant 37 is supplied from the coolant nozzle 36, and the grinding tool 21 is rotated and oscillated in a spherical center to move the workpiece 25 held by the holder 26. 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 pivotally pivots about the center of curvature O ₁ of the processing surface 21a as a fulcrum in conjunction with the pivotal pivoting of the rotary shaft 22. During this swing, the terminal 3
A 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, it means that the center of rotation of the machined surface 21a and the electrolytic surface 28a are aligned or close to each other, and therefore the entire surface of the machined 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 concentrates on the edge portion 35a of the copper alloy layer 35. Therefore, although the elution of the copper alloy layer 35 is promoted, the bond elution at the end surface of the grinding tool 21 is at the same level as that of the other processed surface 21a, and the electrolysis of the entire processed surface 21a is performed uniformly.

According to this embodiment, the electrolytic action is not concentrated on the end surface of the grinding tool 21, and the electrolytic dressing of the entire surface of the machined surface 21a can be performed uniformly, so that the shape of the machined surface 21a can be maintained. The member 25 to be processed can be processed with high accuracy, and the amount of abrasive grains falling off is reduced, so that the member 25 to be processed can be prevented from being scratched by rolling of the abrasive grains. Further, even if the workpiece 21 comes into contact with the copper alloy layer 35, the oxide serves as a cushion and is not scratched.

The same effect can be obtained by using an aluminum alloy instead of the 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]

Second Embodiment FIG. 3 is a schematic configuration diagram showing a second embodiment of the present invention with a partial cross section. In this embodiment, instead of the copper alloy 35 in the first embodiment, a low melting point metal layer 40 is provided on the outer peripheral surface of the grinding tool 21, and the workpiece 25 is changed from a concave shape to a convex shape. In accordance with this, the machining surface 21a of the grinding tool 21 is changed from a convex shape to a concave shape, and other configurations are made of the same constituent parts, and the same constituent parts are designated by the same reference numerals, and the description thereof will be omitted. To 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 the present embodiment, the concave machining surface 21a of the grinding tool 21 is brought into contact with the convex machining surface 25a of the workpiece 25, and the center of curvature O ₂ of the machining surface 21a is used as a fulcrum. The member 25 to be processed is subjected to grinding in the same manner as in Example 1 by swinging the heart. In this grinding process, the electrode 28 has the first embodiment.
Electricity is applied at the same position as in (1) to electrolytically dress the surface to be processed 25a. At this time, the electrolytic action concentrates on the edge portion 40a of the low melting point metal layer 40 as in the first embodiment.

According to this embodiment, it is possible to prevent the shape of the grinding tool 21 from collapsing as in the first embodiment. Further, since the low melting point metal layer 40 is softer than the metal bond (iron-based, bronze-based, nickel-based) of the grinding tool 21, it has a great effect in preventing generation of scratches due to friction with the workpiece 25. Further, since the low melting point metal can be sintered at a low temperature after sintering of the grinding tool, it is easy in terms of manufacturing method. In addition, fine abrasive grains (diamond, cerium oxide, alumina) may be mixed in the low melting point metal as a lubricant for reducing friction at the time of contacting the workpiece 25.

FIG. 4 is a sectional view showing a modification of the grinding tool in the second embodiment. The grinding tool 21 of the modified example is used when a hole 41 is provided at the center of the grinding tool 22 and grinding is performed while supplying a coolant from the hole 41. The inner peripheral surface of the hole 41 is the same as the outer peripheral surface. Low melting point metal layer 4
0 is provided. Therefore, like the outer peripheral surface, it is possible to prevent the shape of the center portion of the machined surface 21a from collapsing, and to prevent scratches on the workpiece due to the 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. In the present embodiment, the number of the members 25 to be processed in the first embodiment is changed from one piece to another piece, and accordingly, a plurality of pieces of holders 51 are arranged instead of the electrodes 28 and the holders 26. The difference is 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 the same components, and the same components are designated by the same reference numerals. However, 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 is obtained. Also, several other workpieces 2
The other several holders 51 for holding 5 are electrically connected to the cathode of the flowing power source 29 via the connector 27, and are configured to also serve as the electrode 28 of the first embodiment.

In this embodiment, the electrolytic action concentrates on the edge portion 50a of the silver paste 50. Other functions are similar to those of the first embodiment.

According to the present embodiment, the strength of the silver paste 50 is substantially equal to the strength of the resin, so that it is very soft and brittle, which is very effective in preventing scratches due to friction with the member 25 to be processed. Further, it can be applied to a finished product of a usual metal bond grinding tool and adhered at about 150 degrees. It should be noted that fine abrasive grains (diamond, cerium oxide, alumina) may be mixed in the silver paste 50 as a lubricant for reducing friction at the time of contacting the workpiece 25.

[0030]

[Embodiment 4] FIG. 6 is a schematic configuration diagram showing Embodiment 4 of the present invention in a partial cross section. In the present embodiment, the first embodiment
In place of the grinding tool 21 in the above, a large number of pellet grinding tools 61 are bonded to a bonding jig 60, and a copper alloy layer 62 is arranged on the outer peripheral surface of each of the pellet grinding tools 61. The structure is composed of the same constituent parts, and the same constituent parts are designated by the same reference numerals, and the description thereof will be omitted.

In the present embodiment, a large number of pellet grinding tools 61 held on the rotary shaft via the attachment jig 60.
By swinging the ball about the swing center O ₁ as a fulcrum.
Grinding process is performed. Then, when the electrode 28 coincides with the center of rotation on the surface of the attaching jig 60 or is located in the vicinity thereof, the terminal 31 and the conductive portion 32a contact each other, and the processed surface of each pellet grinding tool 61 is the same as that in the first embodiment. Electrolytically dressed. At this time, the electrolytic action is concentrated 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 that of the first embodiment can be obtained by using a large number of pellet grinding tools 61 attached to the grinding tool.

[0033]

As described above, according to the electrolytic in-process dressing grinding apparatus of the present invention, a conductive layer is provided on the peripheral surface of a grinding tool, and an electrolytic action is exerted on the conductive layer when electrolytically dressing the machined surface of the grinding tool. Since the concentration can be concentrated, it is possible to prevent the concentration of electrolysis on the edge portion of the grinding tool, and perform uniform electrolytic dressing on the entire processed surface. As a result, the shape of the grinding tool can be maintained, and excessive grinding particles can be prevented from falling off, and grinding can be performed while preventing the workpiece from being scratched due to rolling of the falling abrasive particles.

[Brief description of drawings]

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

FIG. 2 is a view on arrow A in FIG.

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

FIG. 4 is a cross-sectional view showing a modified example of the grinding tool according to the second embodiment of the present invention.

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

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

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

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

[Explanation of symbols]

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

Claims (1)

[Claims] 1. A conductive grinding tool connected to an anode of a DC power supply is rotatably provided, and a ring-shaped electrode connected to a cathode of a DC power supply is provided so as to be opposed to a processed surface of the conductive grinding tool, and In an electrolytic in-process dressing grinding device provided with a means for supplying a coolant between a conductive grinding tool and an electrode, a conductive layer made of a paste obtained by mixing metal powder with metal or resin is provided on the peripheral surface of the conductive grinding tool. An electrolytic in-process dressing grinding device characterized by being provided.