JPH11221765A - Gringing device and grinding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding device and a grinding method which can maintain a good grinding property by maintaining a surface property only by a discharge machining and a weak electrolytic function, in a grinding process by a fine abrasive grain grinding wheel. SOLUTION: This grinding device 20 is provided with a grinding wheel 2 grinding a work 3, a spindle 1 to drive to rotate the grinding wheel 2 by fixing it; a spindle driving part 5 to move the grinding wheel 2 together with the spindle 1 up and down and to the left and the right, as well as to control the rotating drive of the spindle 1 by connecting to the spindle 1; a table 4 to fix the wok 3, a table driving part 6 to move the work 3 to the front side and the rear side through the table 4; a nozzle 7a to exhaust and feed a working fluid 7c to the clearance of the grinding wheel 2 and the work 3, a discharge machining head 8 to process the surface of the grinding wheel 2, a discharge machining power source 9 connected electrically to the discharge machining head 8 and the spindle 1 of the grinding work device 20 through leads 10a and 10b; and a nozzle 7b to exhaust and feed the processing liquid 7c to the discharge processing head 8 and the opposite part of the grinding wheel 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding apparatus and a grinding method for performing a grinding process using a grindstone, and more particularly, to a discharge truing method for maintaining the shape of the grindstone in an appropriate shape and a grindstone. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding apparatus and a grinding method capable of simultaneously performing electrolytic dressing for maintaining the shape and performing processing with high shape accuracy.

[0002]

2. Description of the Related Art Conventionally, in grinding processing, when processing a workpiece such as a metal or ceramic with a grindstone in which abrasive grains are bonded by a bonding material, processing chips are generated between the abrasive grains. The adhesion causes clogging, which lowers the grinding performance. In particular, in order to improve the surface roughness of the grindstone, it is necessary to use a grindstone with a small abrasive grain size and a large grindstone. In practice, it is difficult to make full use of it, and it is difficult to stably perform so-called mirror grinding.

As means for solving this problem, Japanese Patent Laid-Open No.
Japanese Patent Application Publication No. 196968 discloses that a metal-bonded grindstone using fine abrasive grains is subjected to dressing (sharpening) during grinding by electrolytic action to perform mirror-surface grinding. This is to eliminate grinding anomalies such as increase in grinding resistance and grinding burn due to clogging of grinding stones, crushing of the processed surface, etc., so that a grinding wheel with a large grinding wheel count can be used, but it is used for dressing. The electrolytic action acts on the processing waste adhering to the surface of the grinding wheel and also on the grinding wheel itself, and in particular, it acts on the metal binder that holds the abrasive grains, dissolving or transforming it, causing the grinding wheel to be consumed or the grinding wheel to be worn. Since the diameter is changed, it is extremely difficult to make the shape accuracy of the workpiece after the grinding process to be a precise shape accuracy of 5 μm or less, particularly 1 μm or less.

In general, when performing grinding, it is necessary to perform truing (shaping) of a grindstone in advance. When using the above-mentioned metal bond whetstone, mechanical processing methods such as a method using a diamond truer and a method using a harder metal bond whetstone have been conventionally known. On the other hand, a large reaction force is applied, so that the processing accuracy is deteriorated due to the displacement of the grindstone, or a desired shape cannot be obtained due to wear of the truer itself.

As a method for solving these problems, Japanese Patent Publication No.
Japanese Patent No. 38346 discloses an electric discharge machining using a traveling wire, in which the machining reaction force is reduced to a negligible level so that the wear of the tool can be ignored. Further, in Japanese Patent Publication No. 2-38346, since truing can be performed on a processing machine that performs grinding, removal of a grindstone can be made unnecessary, and compared with a case where processing was performed using a conventional truing dedicated machine. It is excellent in efficiency and precision.

[0006] On the other hand, Japanese Patent Publication No. 2-38346 presupposes the use of an NC machine tool, in which a grinding wheel is mounted on the NC machine tool for grinding, and in order to perform electric discharge machining, a grinding wheel controlled by an NC device is used. It is no longer necessary to remove the grindstone, but each time the shaping of the grindstone is required, the processing must be interrupted and the shaping must be performed by moving the grindstone to the position where the wire traveling device is installed. In addition, the work efficiency was reduced, and the positioning error caused by moving the grindstone over a long distance was increased, and the processing accuracy was sometimes reduced. Further, in order to perform clogging, it is necessary to separately perform a dressing process, so that the operation time has been long.

Japanese Patent Application Laid-Open No. 3-196968 discloses a method in which an electrode made of a conductive magnet placed in the vicinity of a grindstone is moved in two axial directions, a voltage is applied, and while the dressing is performed by electrolysis, the abrasive grains on the electrode surface are removed. Indicates that truing is performed. In Japanese Unexamined Patent Publication (Kokai) No. 3-196968, since the electrode and the grinding stone are in contact with each other, not only the displacement of the grinding stone or the electrode due to the reaction force occurs, but also the electrode is consumed during truing. The truing accuracy deteriorated like the truing using the processing. Therefore, in JP-A-3-196968, although it is mainly effective for dressing and has the ability of truing to give a shape to a grindstone, the truing accuracy is limited, and particularly high-precision processing cannot be performed. .

On the other hand, in Japanese Patent Application Laid-Open No. Hei 6-210566, a discharge gap in wire electric discharge machining is detected by a wire electric discharge machine having a moving table independent of a grindstone, and the work is ground by the grindstone. This shows that truing of the grindstone according to the shape change of the working surface of the grindstone can be easily performed during processing. This Japanese Unexamined Patent Publication No.
According to Japanese Patent No. 210566, by performing truing of a grindstone in response to a change in shape due to wear of the grindstone caused during processing, extremely high shape accuracy can be realized. Also, since the truing of this whetstone is performed simultaneously with the grinding process, without interrupting the grinding process,
High-precision grinding was realized.

As described above, in the conventional grinding, the processing with extremely small surface roughness can be performed by the electrolytic in-process dressing technique, and the processing with extremely high shape precision can be performed by the discharge truing technique. However, in the above-mentioned grinding processing, the electrolytic in-process dressing technique and the discharge truing technique were not compatible, and it was difficult to perform processing with extremely small surface roughness and extremely high shape accuracy.

On the other hand, a grinding apparatus recently proposed by the applicant includes a discharge truing device and an electrolytic dressing device, and these devices use an aqueous solution of an electrolyte in which discharge truing and electrolytic dressing can be simultaneously generated. It is used to perform both discharge truing and electrolytic dressing. This electric discharge truing apparatus performs electric discharge machining by a direct current power supply of a voltage of 200 V and an electric discharge machining power supply (RC discharge circuit) having a capacitor of a capacity of 100 pF.

In this grinding apparatus, there is an advantage that the deformation of the grinding wheel, which is a drawback of the electrolytic dressing for removing the clogging of the grinding wheel, can be corrected in real time by electric discharge truing. While a strong electrolytic dressing can be performed, a shape collapse can be corrected by truing.

That is, when grinding is performed with a coarse grinding wheel having a grinding wheel number of about 1000, the spacing between the abrasive grains (chip pocket) is large because the abrasive grain size is relatively large, and clogging may occur. Since it does not easily occur, it can be dealt with by relatively weak electrolytic dressing and discharge truing.

[0013]

However, according to the grinding apparatus recently proposed by the present applicant, ultrafine abrasive grains having a large abrasive grain number, for example, 4000th (average grain diameter of 4 μm) are used. When performing mirror finishing with a small surface roughness using a grindstone, clogging is more likely to occur compared to a grindstone using coarse abrasive grains (average particle size: 12 μm) of about 1000 counts, and electrolytic dressing must be strengthened. Must be added to the grinding wheel, causing a large deformation in the shape of the grinding wheel, which will continue to be corrected by electric discharge truing, resulting in excessive wear of the grinding wheel in the radial direction and a grinding wheel to maintain a constant cutting depth. However, there is a problem that the feed control becomes difficult, and the precision of the grinding process is reduced.

Further, since both an electrolytic dressing device and a discharge truing device are required, the grinding machine becomes complicated as a whole, and furthermore, the discharge truing must be provided in accordance with the shape collapse due to the electrolytic dressing. There has been a problem that it is difficult to properly control these.

Therefore, an object of the present invention is to provide a method for maintaining the surface properties only by electric discharge machining and a weak electrolytic action without the need to apply a strong electrolytic dressing even in the case of grinding using a fine abrasive grindstone. An object of the present invention is to provide a grinding apparatus and a grinding method capable of preventing an increase in grinding resistance and maintaining good grindability without causing the problem described above.

[0016]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a conductive grindstone that is driven to rotate with the rotation of a spindle, a table on which a workpiece is mounted, and a movement of the grindstone and the table. A grinding device having a driving means for bringing a grinding wheel and a workpiece into contact with each other, wherein an electrode which is close to and opposed to the grinding wheel, and a process for supplying a working liquid of an aqueous solution containing an electrolyte between the grinding wheel and the electrode A liquid supply means, a discharge power supply connected to the grindstone and the electrode, and applying a voltage for causing a discharge between the grindstone and the electrode; and a discharge in accordance with the grain diameter of the grindstone and the electric resistivity of the machining fluid by controlling the discharge power supply. A control unit is provided for simultaneously applying dressing and truing to the grindstone in accordance with the grain size of the grindstone by supplying energy and electrolytic energy between the grindstone and the electrode to cause a discharge and an electrolytic action between the grindstone and the electrode. Providing grinding apparatus according to claim.

In order to achieve the above object, a grinding process for driving and rotating a conductive grindstone, moving the workpiece and the grindstone, bringing the grindstone into contact with the workpiece, and grinding the workpiece. In the method, an electrode is opposed to a grinding wheel in close proximity, a working fluid of an aqueous solution containing an electrolyte is supplied between the grinding wheel and the electrode, and a discharge energy and an electrolysis corresponding to a particle diameter of the grinding wheel and an electric resistivity of the working fluid are determined. A grinding method characterized by simultaneously applying dressing and truing to a grindstone according to the grain size of the grindstone by supplying energy between the grindstone and the electrode to cause discharge and electrolytic action between the grindstone and the electrode. provide.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The grinding apparatus and the grinding method of the present invention will be described below in detail.

FIG. 1 shows a grinding apparatus according to the present invention. This grinding device includes a grinding machine 20 and an electric discharge machining unit 25. The grinding machine 20 includes a grindstone 2 that grinds the work 3, a main spindle 1 that fixes and rotates the grindstone 2,
A spindle drive unit 5 connected to the spindle 1 for controlling the rotational drive of the spindle 1 and moving the grindstone 2 up and down and left and right together with the spindle 1 as in feeds B and C; and a table 4 for fixing the work 3 , The work 3 is sent through the table 4 and A
Table driving unit 6 that moves back and forth as in
And a nozzle 7a for ejecting and supplying a machining liquid 7c to a gap between the workpiece 3 and the workpiece 3. The electric discharge machining unit 25 includes an electric discharge machining head 8 for machining the surface of the grindstone 2, and an electric discharge machining power supply electrically connected to the electric discharge machining head 8 and the main shaft 1 of the grinding machine 20 via leads 10 a and 10 b. 9 and
The apparatus includes a nozzle 7b which jets and supplies a machining liquid 7c to an opposing portion between the electric discharge machining head 8 and the grindstone 2, and a control unit 100 which controls each unit in the operation described below.

With the above configuration, the ring-shaped grindstone 2 is
The grindstone 2 is fixed to the main shaft 1 of the grinding machine 20, and can be rotated together with the driving of the main shaft 1. Further, while rotating, the grindstone 2 can be moved up and down and left and right like the feeds B and C integrally with the main spindle 1 by the main spindle drive unit 5 of the grinding machine 20. The grindstone 2 is rotated at a high speed and brought into contact with the work 3, so that the abrasive grains on the surface of the grindstone 2 rub the surface of the work 3, and the grinding work is performed by shaving off the surface of the work 3. A processing liquid 7c is ejected and supplied from a nozzle 7a to a gap between the work 3 and the grindstone 2,
Cool, clean, and lubricate the ground surface. The work 3 is fixed to the table 4 of the grinding machine 20.
The table can be moved back and forth by the driving of the table driving unit 6 as indicated by feed A. By controlling the contact point between the grindstone 2 and the work 3 to an arbitrary position in this way, the surface of the work 3 can be processed into a free shape.

On the other hand, an electric discharge machining head 8 is arranged on the main spindle drive unit 5 of the grinding machine 20 at a position different from the contact portion of the grinding wheel 2 with the work 3 so as to face the grinding stone 2. When the spindle 1 moves in the feed B and C directions by the spindle drive unit 5, the electric discharge machining head 8 can also move while maintaining the relative position with respect to the grindstone 2. A voltage is applied between the electric discharge machining head 8 and the grindstone 2 to perform electric discharge machining at an opposing portion between the electric discharge machining head 8 and the grindstone 2, and truing and dressing are performed simultaneously. At this time, due to the principle of electric discharge machining, the conductive grindstone 2 is gradually removed at the discharge location, whereby the shape of the grindstone 2 is maintained constant and machining waste clogged between the abrasive grains of the grindstone 2. Is removed, so that the cutting edge of the abrasive grains is maintained. The electric discharge machining head 8 and the electric discharge machining power supply 9 are connected by a lead 10a, and the electric discharge machining power supply 9 and the grindstone 2 are electrically connected by a lead 10b via a brush (not shown) contacting the main shaft 1. I have. It is appropriate that the polarity at the time of electric discharge is negative on the electric discharge machining head 8 side and positive on the grindstone 2 side. As for the conditions for the occurrence of discharge, the voltage is 50 to 200 V and the capacitor capacity is 100 V.
pF ~ 3300pF, charge resistance is about 1kΩ,
Discharge is generated by a capacitor charge / discharge type discharge generation method (RC circuit). The conditions for generating the discharge are appropriately adjusted depending on the size of the amount of the abrasive grains protruding from the grindstone 2 and the speed of clogging. For example, when the grindstone 2 has a grindstone number of 4000 or more, the voltage is 100 V or less. Is enough.

The distance between the electric discharge machining head 8 and the grindstone 2 is 1
μm to 5 μm, and when a voltage is applied between the electric discharge machining head 8 and the grindstone 2 by the electric discharge machining power supply 9,
Dielectric breakdown occurs. Further, a machining liquid 7c is jetted from a nozzle 7b to a portion where the electric discharge machining head 8 and the grindstone 2 face each other. Here, the rotation of the grindstone 2 during the actual grinding is several thousand rpm.
m or more, and the processing fluids supplied from the nozzles 7a and 7b are mixed immediately even if they are different.
And the nozzle 7b.

FIG. 2 shows the details of the electric discharge machining head 8.
FIG. 2A shows the electric discharge machining head 8 from the front, and FIG.
(B) shows the electric discharge machining head 8 from the side. FIG.
3A, the electric discharge machining head 8 includes a base plate 81 made of an insulator such as ceramic, and a wire traveling mechanism on the base plate 81, and uses a traveling wire 82 as an electrode for electric discharge machining. . The electrode wire 82 has a diameter of about 0.1 mm and is made of brass. Further, the wire running mechanism rotatably supports a feed-out bobbin 83 of the electrode wire 82, a take-up bobbin 91, a brake roller 84, and rotating rollers 85, 86, 87, and 90 on a base plate 81. A required amount of unused electrode wire 82 is wound around the delivery bobbin 83 in advance. Brake roller 8
4, there are three grooves (not shown) for supporting the electrode wires 82. The electrode wires 82 from the delivery bobbin 83 and the electrode wires 82 from the rotating rollers 85 and 86 are separated from each other. To prevent the running electrode wires 82 from interfering with each other. The brake roller 84 is rotatable around the rotation axis. However, a mechanism (not shown) is provided above the rotation axis to suppress the rotation of the brake roller 84 by frictional force to suppress the rotation by the frictional force. A tension is applied to 82 in a direction opposite to the running direction. This prevents the electrode wires 82 from loosening and avoids troubles such as dropping of the electrode wires 82 from the wire guide 89.

The electrode wire 8 coming out of the brake roller 84
Subsequently, the direction of 2 is changed by a rotating roller 87 and sent to a wire guide 89. The guide arm 88 is attached so as to protrude from the base plate 81, and the wire guide 89 is fixed to the distal end of the guide arm 88 by screwing, so that the wire guide 89 does not rotate. A small guide groove (not shown) having the same width (about 0.1 mm) as the diameter of the electrode wire 82 is cut around the wire guide 89, and the electrode wire 82 slides along the guide groove. And run. The guide groove has a depth of about half the diameter of the electrode wire 82 and a half-moon cross section. One half of the guided electrode wire 82 is gripped in a state of protruding outside the wire guide 89. You.
Then, in the portion of the electrode wire 82 exposed to the outside, electric discharge is generated between the grindstone 2 and electric discharge machining.

Electrode wire 82 past wire guide 89
Is sent to a winding bobbin 91 by changing its direction with a rotating roller 90. The winding bobbin 91 is rotated by a motor (not shown) on the back of the base plate 8 and winds the electrode wire 82 that has passed through the wire guide 89 and the rotating roller 90.

With the above-described wire traveling mechanism, the electrode wire 82 performs electric discharge machining on the grindstone 2 at the tip of the wire guide 89 while traveling. Therefore, the electrode wire 82 consumed at the time of discharge is always replaced with a new part by running, and the gap with the grindstone 2 is kept constant. The running speed of the electrode wire 82 is several mm per minute.
To several tens of mm.

In FIG. 2B, the electric discharge machining head 8
Is fixed to a vertical moving table 93 by a mounting shaft 92, and the vertical moving table 93 is connected and fixed at a right angle to a horizontal moving table 94. These two tables 93
And 94, the electric discharge machining head 8
Positioning control is performed on two axes, vertical or horizontal, such as feed D and feed E with respect to the rotation axis 1 of the grindstone 2. Thus, the distance between the grindstone 2 and the electric discharge machining head 8 can be controlled to a distance at which electric discharge machining can be performed, and the electric discharge machining head 8 can be moved over the entire width of the grindstone 2. It can be shaped into a shape.

Next, the working fluid 7c used will be described. The working fluid 7c is supplied by jetting from the nozzles 7a and 7b shown in FIG. The nozzle 7a has a grindstone 2 and a work 3
Supplies the machining fluid 7c to the grinding portion where the
b supplies the machining fluid 7c to the electric discharge machining part where the electric discharge machining head 8 and the grindstone 2 face each other. Processing liquid 7c for grinding part
Is supplied for lubrication, cooling, and cleaning of the grinding portion, while the supply of the machining fluid 7c to the electric discharge machining portion causes an appropriate insulation between the grindstone 2 and the electrode wire 82 to generate electric discharge, and at the same time, the electric discharge is performed. Performed to remove clogged processing waste. here,
Ideally, the machining fluid 7c at these two locations should be supplied separately for each application. However, in practice, the rotation speed of the grindstone 2 is very high, from several thousand to several tens of thousands of rpm. For this reason, since the respective processing liquids from the nozzles 7a and 7b are mixed, it is very difficult to use separate processing liquids to exert independent functions. Therefore, here, the same machining fluid 7c is supplied to satisfy both functions of the grinding portion and the electric discharge machining portion.

The used working fluid 7c is obtained by further diluting a commercially available electrolytic solution for electrolytic dressing from a concentration generally used. This is because the insulation required for electric discharge machining cannot be obtained with the concentration of the generally used electrolytic dressing solution. Actually, when the resistivity of the machining fluid 7c is 0.1 kΩm or more, discharge can be generated, and
At about Ωm or more, stable electric discharge machining can be performed.
The reason why the machining fluid is not an insulating fluid such as oil or pure water used in general electric discharge machining but a weak electrolytic solution is to superimpose the effect of electrolytic dressing around a discharge occurring. .

FIG. 3 shows a state of electric discharge machining. As shown in FIG. 3, the discharge 11 occurs where the distance between the grinding stone 2 and the electrode wire 82 is short (narrow), but the discharge 11 occurs around the circumference because the distance between the grinding stone 2 and the electrode wire 82 is wide. Does not occur. However, at this time, the working fluid 7
Since c contains the electrolyte, an electrolytic current 12 flows between the grindstone 2 and the electrode wire 82. This can provide an effect of eliminating clogging due to the electrolytic dressing. That is,
In the electric discharge machining of the present invention, the effect of electric discharge truing is generated by the electric discharge 11, and at the same time, the effect of electrolytic dressing is generated by the electrolytic current 12. here,
When the resistivity of the working liquid 7c is 10 kΩm or more, the electric discharge machining is good, but the effect of the electrolytic dressing is almost eliminated. Therefore, the resistivity range of the electrolyte 7c is preferably 0.1 kΩm or more and 10 kΩm or less.

FIGS. 4A and 4B show the relationship between the abrasive grain size of the grindstone 2 and the surface roughness of the bonding material of the grindstone 2 generated by electric discharge machining. In the present invention, since the surface of the bonding material 22 of the grindstone 2 is processed by the electric discharge 11 (FIG. 3) of the electric discharge machining, the surface roughness changes according to the electric discharge machining conditions. In FIG. 4A, since the surface roughness 22a of the bonding material 22 generated by the electric discharge machining is smaller than the size of the abrasive grains 21, the protruding cutting edge 21a of the abrasive grains 21
Although the work 3 can be ground, as shown in FIG. 4B, when the surface roughness 22b of the bonding material 22 is larger than the abrasive grains 21, the grindability of the work 3 by the protruding cutting edge 21a of the abrasive grains 21 is obtained. Will be lost. Therefore, it is desirable to set the energy level of the electric discharge machining so that the surface roughness of the bonding material 22 of the grindstone 2 becomes equal to or smaller than the diameter of the abrasive grains 21 by the electric discharge machining.

Next, the electrical discharge machining of the grindstone 2 using the fine abrasive grains 21 having a large grindstone count will be described. When the grinding device is started, the grindstone 2 is controlled to move relative to the work 3 by the spindle drive unit 5, and the abrasive grains 21 on the surface of the grindstone 2 scrape the surface of the work 3 while rubbing the surface. The workpiece 3 is ground to a desired shape and dimensions.
Before clogging of the grindstone 2 progresses due to the grinding process, discharge truing and electrolytic dressing are performed by the electric discharge machining head 8, and the grindstone 2 always maintains an appropriate surface state and cross-sectional shape (FIG. 4A). Is done. At this time, if the grinding dust clogged between the abrasive grains 21 on the surface of the grindstone 2 is conductive, it is directly removed by the electrolytic current 12 of the electric discharge machining. It is removed when the bond material 22 of the grindstone 2 is removed. This makes it possible to remove clogged grinding debris without interrupting the grinding process, to prevent an increase in the grinding resistance of the grindstone 2 and to maintain good grindability.

Here, according to the conventional grinding apparatus, when the diameter of the abrasive grains 21 of the grindstone 2 used is large and coarse (small number), the distance between the abrasive grains 21 (the gap between the abrasive grains 21 ( Chip pockets) are large and processing chips are not easily clogged, and can be dealt with by applying electrolytic dressing in-process.
The effect on shape collapse is small. However, when the diameter of the abrasive grains 21 is 4
In the case of using a fine abrasive grain grinding wheel 2 having a grinding wheel count of 4000 μm or less with a diameter of μm or less, it is necessary to strengthen the electrolytic dressing because clogging occurs immediately.
The shape of the grinding wheel 2 becomes large, and the shape of the grinding wheel 2 is corrected in combination with electric discharge truing. Therefore, the wear of the grinding stone 2 becomes remarkable, and the cost is increased. Also, a change in the cutting amount to 3 occurs.

On the other hand, according to the grinding apparatus of the present invention, the diameter of the abrasive grains 21 is 4 μm or less and the grinding wheel number is 4000.
Even in the grinding process in which clogging is likely to occur due to the fine abrasive grains 2 or more, strong electrolytic dressing is not necessary, and the shape of the grinding wheel 2 is formed by electric discharge truing by electric discharge machining and weak electrolytic dressing generated around the electric discharge machining portion. Processing debris clogged between the abrasive grains 21 can be removed without causing collapse. Therefore, in the grinding apparatus of the present invention, it is possible to use a fine abrasive grain having an abrasive grain number of 4000 or more and a diameter of the abrasive grain 21 of 4 μm or less, and the volume machining speed of the grinding is about 1 mm 3 / h. Suitable for the following precision grinding. In addition, the grinding stone 2 has C
Conductive metal such as BN (cubic boron nitride) or diamond is suitable for the bonding material 22.

[0035]

As described above, according to the grinding apparatus and the grinding method according to the present invention, since the surface of the grindstone is subjected to electric discharge machining by the working fluid of the electrolyte, the grinding by the fine abrasive grindstone is performed. Even in machining, it is not necessary to give a strong electrolytic dressing, the surface properties can be maintained only by electric discharge machining and weak electrolytic action, there is no problem of grinding wheel shape collapse, good increase in grinding resistance, etc. It has become possible to maintain excellent grinding properties.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a grinding apparatus according to the present invention.

FIG. 2 is a schematic diagram showing an electric discharge machining unit used in the grinding machine of the present invention.

FIG. 3 is a diagram showing an overlapping action of discharge truing and electrolytic dressing of the present invention.

FIG. 4 is a view showing an appropriate surface roughness of a grindstone surface by electric discharge machining in the present invention.

[Explanation of symbols]

 Reference Signs List 1 spindle 2 grindstone 3 work 4 table 5 spindle drive unit 6 table drive unit 7a, 7b nozzle 7c working fluid 8 electric discharge machining head 9 electric discharge machining power supply 10 lead 11 electric discharge 12 electrolytic current 20 grinding machine 21 abrasive grain 21a protruding cutting edge Reference Signs List 22 bonding material 22a, 22b surface roughness 25 electric discharge machining part 81 base plate 82 electrode wire 83 sending out bobbin 84 brake roller 85, 86, 87, 90 rotating roller 88 guide arm 89 wire guide 91 winding bobbin 92 mounting shaft 93 vertical movement table 94 horizontal moving table 100 control unit

Claims (10)

[Claims] 1. A conductive grindstone that is driven to rotate with rotation of a spindle, a table on which a workpiece is mounted, and driving means for moving the grindstone and the table to contact the grindstone and the workpiece. A grinding machine having: a working fluid supply unit for supplying a working fluid of an aqueous solution containing an electrolyte between the grinding wheel and the electrode; A discharge power supply connected to apply a voltage for causing a discharge between the grinding wheel and the electrode; and a discharge energy and an electrolytic energy corresponding to a particle diameter of the grinding wheel and an electric resistivity of the working fluid by controlling the discharge power supply. Is supplied between the grindstone and the electrode to cause discharge and electrolytic action between the grindstone and the electrode, so that dressing and truing according to the particle size of the grindstone can be simultaneously performed on the grindstone. A grinding machine comprising a controller for applying to a stone. 2. The grinding apparatus according to claim 1, wherein said electrode is a wire electrode running along a wire guide supported opposite to said grindstone. 3. The processing liquid according to claim 1, wherein the working fluid is 0.1 kΩm or more and 10 kΩ
3. The grinding machine according to claim 1, wherein the machining fluid has an electric resistivity of not more than m. 4. The grinding wheel according to claim 1, wherein said grinding wheel is a fine abrasive wheel having an abrasive grain number of 4000 or more.
The grinding machine as described. 5. The grinding apparatus according to claim 4, wherein said abrasive grains of said grindstone have a grain size larger than the surface roughness of the working surface of said grindstone immediately after said discharging. 6. A grinding method for driving and rotating a conductive grindstone, moving the workpiece and the grindstone, bringing the grindstone into contact with the workpiece, and grinding the workpiece. An electrode is opposed to the grinding wheel in close proximity, a working fluid of an aqueous solution containing an electrolyte is supplied between the grinding wheel and the electrode, and a discharge energy according to a particle diameter of the grinding wheel and an electrical resistivity of the working fluid is provided. Simultaneously applying dressing and truing to the grindstone according to the particle diameter of the grindstone by supplying electrolytic energy between the grindstone and the electrode to cause discharge and electrolytic action between the grindstone and the electrode. A grinding method characterized by the following. 7. The grinding process according to claim 6, wherein the step of facing the electrode includes the step of facing a wire guide to the grindstone and the step of running the wire electrode along the wire guide. Method. 8. The method according to claim 6, wherein the step of supplying the processing liquid is a step of supplying a processing liquid having an electrical resistivity of 0.1 kΩm or more and 10 kΩm or less between the grinding wheel and the electrode. Or the grinding method according to claim 7. 9. The grinding stone according to claim 6, wherein said grinding stone is a fine abrasive grain having a grain count of 4000 or more.
The grinding method described. 10. The grinding method according to claim 9, wherein said abrasive grains of said grindstone have a grain diameter larger than the surface roughness of the working surface of said grindstone immediately after said discharging.