JP2000042919A - Superprecise grinding method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide superprecise grinding technique for realizing highly efficient and acurate grinding working, in superprecise grinding working utilizing electrolysis in-process dressing. SOLUTION: In a grinding device using a metal bond grinding wheel as a grinding wheel 4, and performing electrolysis dressing during grinding working, a machining allowance grinding surface 4b is formed on the inlet side of a workpiece by truing, and also a finishing working surface 4c is formed on an outlet side. Successively feeding the workpiece W is started in a condition for producing an oxide coat (e) by electrolysis dressing. Consequently highly efficient grinding can be performed to the workpiece W with the coat (e) separated in the surface 4b, while highly accurate grinding can be performed by residual oxide coat (e) in the surface 4c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-precision grinding method and a grinding apparatus, and more particularly to a grinding technique using a super-abrasive grindstone utilizing electrolytic in-process dressing.

[0002]

2. Description of the Related Art In recent years, as one of the advanced precision processing techniques,
Attention has been paid to ultra-precision grinding technology using super-abrasive grindstones. Particularly, diamond grindstones that combine diamond abrasive grains with a metal-based bonding material (metal bond) are ideal for grinding hard and brittle materials such as ceramics. It is suitably used as a simple whetstone.

[0003] The truing and dressing of such a superabrasive grindstone is difficult with conventional general mechanical truing and dressing techniques, and the work takes a long time. was there.

[0004] For this reason, recently, an electric truing and dressing technique such as discharge truing and electrolytic dressing has been increasingly applied, focusing on the fact that this kind of superabrasive grindstone has conductivity.

[0005] That is, the discharge truing is to perform truing using a discharge action, and is generally applied to the truing of a metal bond grindstone. In the case of a centerless grinding machine equipped with a grinding wheel made of a metal-bonded diamond grinding wheel, this discharge truing has a grinding wheel with a (+) pole and faces the grinding wheel surface (cylindrical grinding surface) of the grinding wheel. The discharge truer (discharge truer electrode) composed of a metal disk provided at regular intervals is used as a negative electrode, and positive and negative voltages are applied to these wheels while rotating the grinding wheel and the discharge truer at a predetermined speed. Thus, the metal bond portion on the surface of the grinding wheel is dissolved and removed by the discharge action between the two electrodes, so that the protruding state of the abrasive grains on the grinding surface is formed and maintained.

[0006] On the other hand, the electrolytic dressing, which performs dressing using an electrolytic action, is also generally applied to dressing of a metal bond grindstone. A typical example of this electrolytic dressing is Electrolytic In-process Dressing (EL).
ID), a metal bond
Taking a centerless grinder equipped with a grinding wheel made of diamond grinding wheels as an example, the grinding wheel has a (+) pole,
Dressing electrodes provided at regular intervals opposite to the grinding wheel surface (cylindrical grinding surface) of the grinding wheel are used as (-) poles, and a coolant (electrolyte) is supplied to these gaps during grinding of the workpiece. By flowing a direct current, the metal bond portion on the ground surface is eluted by the electrolytic action.

FIG. 6 shows a specific mechanism during the electrolytic dressing. FIG. 6 (a) shows a state in which the grinding wheel surface of the metal bond grinding wheel a having the (+) pole is worn, and the gap between the grinding wheel surface and the electrode surface of the dressing electrode b having the (-) pole. A DC current is supplied while a coolant (electrolyte) is supplied to the battery. Then, by the electrolytic action, first, the metal component (iron) d in the metal bond c on the grinding wheel surface elutes and ionizes, and a chip pocket is formed on the grinding wheel surface (FIG. 6 (b)). An oxide film e of the metal component d is formed on the surface of the grinding wheel (FIG. 6C).
The oxide film e maintains the protruding state of the abrasive grains f on the grindstone surface, and the oxide film e imparts elasticity to the holding of the abrasive grains. As a result, highly accurate grinding is realized. I have.

[0008]

However, such conventional techniques, particularly ELID grinding, have the following problems, and further improvements have been demanded.

That is, in the conventional ELID grinding, due to the difficulty of truing of a metal bond grindstone, the shape of the grindstone surface after truing is relatively flat as shown in FIG. ) Shape.

[0010] For this reason, if it is attempted to perform high-efficiency grinding by sulfeed grinding or traverse grinding using a grinding wheel having a flat grinding wheel surface as described above, a notch is given to the workpiece W, As shown in FIG. 5 (b), as the work W progresses, the soft oxide film e formed on the grindstone surface is scraped and peeled off, and when the work W passes through the grindstone surface, Was completely removed (FIG. 5 (c)).

In other words, when a high-efficiency grinding process is performed by the conventional ELID grinding, the oxide film e on the surface of the grinding wheel is completely removed by the passage of the workpiece W, and the abrasive grains have elasticity. However, there is a problem in that the advantage of ELID grinding that high precision grinding is realized by holding the above can not be enjoyed.

The present invention has been made in view of such a conventional problem, and has as its object to mainly provide a high-efficiency and high-precision grinding in ultra-precision grinding using electrolytic in-process dressing. An object of the present invention is to provide an ultra-precision grinding technology capable of realizing a grinding process.

[0013]

In order to achieve the above object, the ultra-precision grinding method of the present invention uses a conductive metal bond grindstone in which abrasive grains are bonded by a conductive metal bond as a grinding wheel. In a grinding machine that performs electrolytic dressing on the grindstone surface of a neutral metal bond grindstone,
Prior to the electrolytic dressing, truing is performed on the grinding wheel so as to form a machining allowance grinding portion having a predetermined shape and a finishing portion having a predetermined shape.

Further, the ultra-precision grinding device of the present invention uses a conductive metal bond grindstone in which abrasive grains are bonded by a conductive metal bond as a grinding wheel, and performs electrolysis on the grindstone surface of the conductive metal bond grindstone. In a grinding device for performing dressing, the grinding device includes a truing device, and the truing device forms a tapered surface for grinding a machining allowance of a workpiece on an entrance side of the workpiece on a grinding wheel surface of the grinding wheel. In addition, a tapered surface for performing finishing by the electrolytic dressing is formed on the outlet side of the workpiece.

In the present invention, a metal bond grindstone capable of performing highly efficient grinding is used as a grindstone of a grinder for performing electrolytic dressing. First, by truing the surface of the grindstone, a tapered surface (grinding portion) for grinding a machining allowance of the workpiece is formed on the entrance side of the workpiece on the surface of the grindstone, and the above-mentioned is also formed on the exit side of the workpiece. A tapered surface (finish portion) is formed so that the finish process can be performed by an oxide film formed on the surface of the grindstone by electrolytic dressing (see FIG. 2A).

Next, electrolytic dressing is performed to form an oxide film on the grindstone surface (see FIG. 2 (b)). In this state, a workpiece is fed from the inlet side of the grinding wheel. As a result, the workpiece starts to contact with the tapered surface for machining of the cut formed on the entrance side, and as a result, the oxide film formed on the tapered surface for machining of the cut as the feeding of the workpiece progresses. On the other hand, the workpiece is subjected to highly efficient grinding by the metal bond portion appearing after the peeling (see FIG. 2 (c)).

Then, when the grinding further proceeds, and the workpiece passes through the tapered surface for the off-set grinding, it passes through the tapered surface for finishing provided on the outlet side of the grinding wheel. At this time, the tapered surface formed here,
By forming the taper with an inclination opposite to that of the taper surface for the above-mentioned grinding for grinding, and setting this inclination to an inclination capable of finishing with an oxide film, the oxide film on the taper surface for the finishing process can be machined. Finishing is performed on the passing workpiece without being removed by the passing of the workpiece (see FIG. 2 (d)).

As a result, high-efficiency grinding is performed on the tapered surface for take-off grinding, and high-precision grinding is performed on the subsequent tapered surface for finishing by using an elastic oxide film. Grinding that satisfies the two conditions of efficiency and high accuracy is realized.

In the above description, the inlet side of the workpiece means the side where the workpiece is put into the grinding wheel in the case of through grinding, and the outlet side of the workpiece similarly means the workpiece. Means the side discharged from the grinding wheel. Therefore, when one or both of the grinding wheel and the workpiece move and perform grinding as in traverse grinding, the side of the grinding wheel where grinding is started is defined as the inlet side, and the opposite side to the inlet side is used. The whetstone portion at the position is the exit side.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an embodiment of the ultra-precision grinding apparatus according to the present invention. The grinding device 1 is specifically a centerless grinding machine, which includes an electrolytic dressing device 2 as a dressing device and a discharge truing device 3 as a truing device.

The basic structure of the centerless grinding machine is the same as that of a conventional well-known grinding machine. The centerless grinding machine mainly includes a grinding wheel 4, an adjusting wheel 5, a blade 6, and the like. Is rotatably supported by the adjusting wheel 5 and the blade 6, and is ground while being passed through between the grinding wheel 4 and the adjusting wheel 5 in the axial direction.

The grinding wheel 4 is made of a conductive metal bond whetstone in which abrasive grains are bonded by a conductive metal bond, and the whetstone surface 4a is a substantially cylindrical cylindrical grinding surface. As abrasive grains, fine diamond abrasive grains or CBN
(Cubic boron nitride) So-called superabrasives such as abrasives are used.

Although not specifically shown, the grinding wheel 4 is rotatably supported on a grinding wheel base (not shown) via a grinding wheel shaft 7 and is linked to a rotary drive source via a power transmission mechanism. Have been. The grinding wheel 4 is electrically connected to a (+) pole of a power supply 9 via a power supply 8.

In the electrolytic dressing apparatus 2, the dressing electrode 10 is arranged at a position deviating from a grinding position of the grinding wheel 4, that is, a rotational support position of the workpiece W (an upper position of the grinding wheel 4 in the illustrated case). In addition, although not shown, an electrolytic solution supply nozzle is provided between the grinding surface 4a of the grinding wheel 4 and the annular electrode surface 10a of the dressing electrode 10. A power supply 11 is connected to the dressing electrode 10, and the power supply 11 is electrically connected to the (−) pole of the power supply 9.

The discharge truing device 3 has a discharge truing electrode 31 disposed on the opposite side of the adjusting wheel 5 with respect to the grinding wheel 4. In other words, the discharge truing device 3
Is disposed on the upstream side in the rotation direction of the grinding wheel 4 with respect to the electrolytic dressing apparatus 2.

The discharge truing electrode 31 is specifically in the form of a small disk having a narrow width, and its outer peripheral surface portion is
The cylindrical electrode surface 31a is opposed to the grinding surface 4a of the grinding wheel 4.

Although not specifically shown, the discharge truing electrode 31 is rotatably supported on the discharge truing electrode base via a discharge truing electrode shaft arranged in parallel with the grinding wheel shaft 7 and has a power source. It is linked to a rotary drive source via a transmission mechanism. As a result, the discharge truing electrode 31 is driven to rotate in a state where the electrode surface 31a is opposed to the grinding surface 4a of the grinding wheel 4 so as to be parallel to the grinding surface 4a.

The discharge truing electrode 31 is slidable in a direction (arrow direction) parallel to the grinding wheel shaft 7 of the grinding wheel 4, and is linked to a slide drive source to grind the grinding wheel 4. The traverse moves in the direction of the grinding wheel axis 7 along the surface 4a.

The discharge truing electrode 31 is used together with the electrolytic dressing electrode 10 to discharge and switch electrodes.
A power supply 9 is supplied via an electrolysis switching unit (switching operation unit) 12.
Is electrically connected to Specifically, the discharge truing electrode 31 is electrically connected to the discharge / electrolysis switching unit 12 via the power supply 32, and the discharge / electrolysis switching unit 12 is electrically connected to the (−) pole of the power supply 9. Being
The negative electrode is a discharge truing electrode. Therefore, by manually or automatically switching the discharge / electrolysis switching unit 12, the discharge truing electrode 31 is switched.
And the electrolytic dressing apparatus 10 are selectively switched.

In the centerless grinding machine configured as described above, the workpiece W is driven to rotate on the surface of the workpiece while being center-rotated and supported by the adjusting wheel 5 driven to rotate by the blade 6. Grinding is performed by the grinding wheel surface 4a of the grinding wheel 4, and during this grinding, the dressing device 2 performs in-process electrolytic dressing according to the properties of the grinding surface 4a as needed.

In this electrolytic dressing, an electrolytic solution supply nozzle (not shown) supplies an electrolytic coolant between the grinding surface 4a and the annular electrode surface 10a of the dressing electrode 10, and the grinding wheel 4 and the dressing electrode 10 DC current is supplied to the Then, due to the electrolytic action, the conductive metal component on the grinding surface 4a is eluted, the clogging on the grinding surface 4a is removed in-process, and the projected state of the abrasive grains is recovered and maintained.

In this case, as shown in FIG. 6 (b), the metal component in the metal bond c is ionized by the electrolytic action and elutes into the coolant. As a result, the ground surface 4a f is held by the elastic oxide film e (FIG. 6C).

As a result, a sufficient amount of abrasive grains can be obtained on the grinding surface 4a, and the abrasive grains f are held elastically by the elasticity of the oxide film e. High grinding accuracy (surface roughness) can be obtained without occurrence.

By the way, in the grinding apparatus 1 of the present invention, prior to such grinding, the ground surface 4a is tooled into a predetermined shape by the discharge truing by the discharge truing apparatus 3.

That is, the discharge truing here is:
Of the grinding surface 4a on which the above-mentioned electrolytic dressing is performed, the work W is ground between the grinding wheel 4 and the adjusting wheel 5 (that is, the work entrance side). Grinding surface (cutting grinding portion) 4b for forming the workpiece W is formed on the discharge side (exit side) of the workpiece W.
Finishing surface (finishing part) 4 for applying finishing to the surface
c is formed.

Specifically, the discharge truing electrode 31
In the direction parallel to the grinding wheel axis 7 of the grinding wheel 4 (the direction of the arrow).
Then, discharge truing is performed while sliding the workpiece so that the ground surface 4a has a shape as shown in FIG. 2 (a).

That is, by discharge truing, a tapered surface having an inclination corresponding to the allowance L of the workpiece W is formed on the inlet side of the workpiece as the replacement grinding surface 4b, and the tapered surface is continuously connected to the replacement grinding surface 4b. As a result, a tapered surface having a gentle inclination in the direction opposite to the above-mentioned stock removal grinding surface 4b toward the exit side of the workpiece W is formed as the finish processing surface 4c. As described later, this is based on the premise that the oxide film e formed on the replacement grinding surface 4b by electrolytic dressing is peeled off by the workpiece W during grinding.
This is because the oxide film e formed on the finish processing surface 4c partially remains even when the workpiece W passes. Therefore, the inclination of the machining surface 4b is determined according to the machining allowance of the workpiece W as described above, while the finishing surface 4b is determined.
The inclination of c is extremely small such that the oxide film e remains.

In the present embodiment, a tapered surface 4d for discharging the workpiece is formed by the truing so as to be continuous with the finishing surface 4c so that the inclination becomes steeper. This corresponds to the conventional spark-out zone. Here, FIG. 2 (a) is an explanatory drawing emphasized for understanding the shapes of the above-mentioned stock removal grinding surface 4b, finish processing surface 4c, and part 4d for discharging the workpiece.

This discharge truing is performed at any time during the grinding process or while the grinding process is stopped, depending on the properties of the grinding surface 4a of the grinding wheel 4. Specifically, the discharge truing electrode 31 is applied to the grinding surface 4a. While being traversed while rotating, the grinding wheel 4 and the discharge truing electrode 3
1, a DC current is applied to the ground surface 4a.
Is melted and removed by the discharge action to form chip pockets, and the protrusion amount of abrasive grains on the grinding surface 4a is made uniform.

In this case, the electrode surface 31a and the ground surface 4a
To prevent intrusion of cooling water etc. into the discharge area between
Cooling air is supplied from a cooling air nozzle (not shown) to this discharge area.

When the discharge truing is completed, the discharge / electrolysis switching unit 12 subsequently operates
From the discharge truing electrode 31 to the electrolytic dressing electrode 1
0 is operated so as to operate, and the above-described electrolytic dressing by the electrolytic dressing apparatus 2 is performed in-process.

As described above, before the electrolytic dressing, the predetermined tapered surfaces 4b to 4d are formed on the ground surface 4a by truing. In this state, by performing in-process electrolytic dressing, the present invention provides:
The workpiece W is processed with high efficiency and high precision as described below.

FIG. 2 shows the working process at that time. First, the ground surface 4a is trued into the above-described predetermined shape by the discharge truing (see FIG. 2 (a)). When electrolytic dressing is performed in this state, an oxide film e is formed over the front surface of the ground surface 4a (see FIG. 2A). (See FIG. 2 (b)).

When the workpiece W is fed in the direction of the arrow, the corners of the workpiece W start to contact the above-described grinding surface 4b, and are formed on the grinding surface 4b as the workpiece W advances. At the same time as the oxide film e is peeled off, the allowance is ground by the allowance grinding surface 4b. At this time, since the abrasive grains are held by the metal bond having a strong holding force on the replacement grinding surface 4b after the oxide film e has fallen, highly efficient grinding is realized by the replacement grinding surface 4b (FIG. 2 (c)).

On the other hand, the workpiece W, of which the machining allowance has been ground by the machining ground surface 4b, reaches the subsequent finishing machined surface 4c as the workpiece W advances. On the finishing surface 4c, the oxide film e is peeled off by the workpiece W in the same manner as the above-mentioned machining surface 4b, but here, the tapered surface is formed by the machining surface 4b.
Since only the uppermost layer of the oxide film e is peeled off, a part of the oxide film e remains on the finishing surface 4c (FIG. 3). reference).

Therefore, the workpiece W is moved to the finishing surface 4c.
When passing through, high-precision grinding is realized by the abrasive grains held elastically by the oxide film e.
In other words, the workpiece W that has been subjected to high-efficiency grinding on the stock removal grinding surface 4b has high precision grinding on the finishing surface 4c by the abrasive grains held as loose abrasive grains by the remaining oxide film e. Processing is performed. Further, at this time, since the metal bond portion of the grinding wheel does not directly contact the workpiece W due to the remaining oxide film e, so-called mirror grinding can be performed without scratching the surface of the workpiece W. Become.

Then, the finished workpiece W is
The workpiece is discharged to the outside through the tapered surface 4d for discharging the workpiece, which is provided continuously to the finishing surface 4c.

As described above, according to the present invention, the grinding surface 4a is replaced by the discharge truing by using a tapered surface having a strong inclination for grinding and a gentle taper surface for finishing which is provided continuously in the opposite direction. In addition, two effects of high-efficiency grinding, which is an advantage of a metal bond grinding wheel, and high-precision grinding by ELID grinding are simultaneously exhibited.

The above-described embodiment merely shows a preferred embodiment of the present invention, and the present invention is not limited to this, and various design changes can be made within the scope.

For example, the above-described embodiment shows a case where the present invention is applied to a through-feed type centerless grinder as shown in FIG. 4 (a). It can also be applied to grinding machines of other grinding methods.

In other words, when applied to a cylindrical grinding machine in FIG. 4B, and when applied to a surface grinding machine in FIG.
1 shows an example of a schematic configuration when applied to a double-sided surface grinder. In any of these cases, the above-mentioned machining surface 4b is provided on the entrance side where the workpiece W is fed into the grindstone, and the finishing surface 4c is provided on the side opposite to the entrance side. Note that, in these illustrated examples, the case where the workpiece W moves is shown, but it is of course possible to adopt a configuration in which a cut is made by moving the grindstone side.

In the above-described embodiment, the discharge truing device is shown as the truing device. However, it is needless to say that the truing can be performed by a mechanical truing device. Further, in the above-described embodiment, the configuration in which the electrolytic dressing is performed during the grinding is shown. However, the electrolytic dressing may be performed prior to the grinding.

[0054]

As described in detail above, according to the present invention,
In ultra-precision grinding using electrolytic dressing,
As a grinding whetstone, using a conductive metal bond whetstone in which abrasive grains are bonded by a conductive metal bond, in a grinding device that performs electrolytic dressing on the whetstone surface of the conductive metal bond whetstone, grinding prior to electrolytic dressing Since the grinding wheel is formed with a predetermined grinding portion having a predetermined shape and a truing is performed to form a finishing portion having a predetermined shape, highly efficient and highly accurate grinding can be performed.

More specifically, of the grindstone surface, a tapered surface for grinding the machining allowance of the workpiece is formed at the entrance side of the workpiece, and the finish processing by the electrolytic dressing is performed at the exit side of the workpiece. As the tapered surface of the grinding wheel is formed, high-efficiency grinding is performed on the inlet side of the grinding wheel due to peeling of the oxide film by feeding in the workpiece, and the residual oxide film is formed on the tapered surface for finish processing. High-precision finish grinding is performed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a centerless grinding machine according to an embodiment of the present invention.

FIG. 2 is an enlarged schematic diagram showing a truing shape, an electrolytic dressing process, and a grinding process in the centerless grinding machine.

FIG. 3 is an enlarged schematic view showing a state of an oxide film on a grinding wheel surface in a grinding process of the centerless grinding machine, and FIG. 2 (d).
It corresponds to.

FIG. 4 is an explanatory diagram illustrating a schematic configuration when the present invention is applied to another type of grinding machine.

FIG. 5 is an enlarged schematic view corresponding to FIG. 2, showing a grinding process in conventional ELID grinding.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Grinding device 2 Electrolytic dressing device 3 Discharge truing device 4 Grinding wheel 4a Grinding surface of grinding wheel (grinding wheel surface) 4b Grinding grinding surface (grinding grinding portion) 4c Finish processing surface (finish processing portion) 4d Tapered surface for discharging workpiece Reference Signs List 5 adjustment wheel 6 blade 8 power supply 9 power supply 10 dressing electrode 10a annular electrode surface of dressing electrode 11 power supply 31 discharge truing electrode 31a cylindrical electrode surface of discharge truing electrode 32 power supply 12 discharge / electrolysis switching unit (switching operation unit) W Workpiece

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[Procedure amendment]

[Submission date] October 26, 1998 (1998.10.
26)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a centerless grinding machine according to an embodiment of the present invention.

FIG. 2 is an enlarged schematic diagram showing a truing shape, an electrolytic dressing process, and a grinding process in the centerless grinding machine.

FIG. 3 is an enlarged schematic view showing a state of an oxide film on a grindstone surface in a grinding process of the centerless grinder;
This corresponds to (d).

FIG. 4 is an explanatory diagram illustrating a schematic configuration when the present invention is applied to another type of grinding machine.

FIG. 5 is an enlarged schematic view corresponding to FIG. 2, showing a grinding process in conventional ELID grinding.

FIG. 6 is an explanatory diagram illustrating a dressing mechanism in electrolytic dressing.

[Description of Signs] 1 Grinding device 2 Electrolytic dressing device 3 Electric discharge truing device 4 Grinding wheel 4a Grinding surface of grinding wheel (grinding wheel surface) 4b Grinding grinding surface (grinding grinding part) 4c Finishing work surface (finish working part) 4d Workpiece Tapered surface for discharge 5 Conditioning wheel 6 Blade 8 Power supply 9 Power supply 10 Dressing electrode 10a Annular electrode surface of dressing electrode 11 Power supply 31 Discharge truing electrode 31a Cylindrical electrode surface of discharge truing electrode 32 Power supply 12 Discharge / electrolysis switching unit (Switch operation part) W Workpiece

Claims (5)

[Claims] 1. A grinding apparatus for performing electrolytic dressing on a grindstone surface of a conductive metal bond grindstone using a conductive metal bond grindstone having abrasive grains bonded by a conductive metal bond as a grinding grindstone, An ultra-precision grinding method characterized by performing a truing process to form a pre-set grinding portion having a predetermined shape and a finishing portion having a predetermined shape on the grinding wheel prior to dressing. 2. The ultra-precision grinding method according to claim 1, wherein the truing is performed while the grinding of the grinding wheel is stopped. 3. The ultra-precision grinding method according to claim 1, wherein said electrolytic dressing is performed during grinding of a grinding wheel. 4. A grinding apparatus for performing electrolytic dressing on a surface of a conductive metal bond grindstone using a conductive metal bond grindstone having abrasive grains bonded by a conductive metal bond as the grinding grindstone, The apparatus is provided with a truing device, and by this truing device, a tapered surface for grinding a machining allowance of a workpiece is formed on an inlet side of a workpiece on the grinding wheel surface of the grinding wheel, and the above-described truing device is provided on an outlet side of the workpiece. A grinding apparatus characterized by forming a tapered surface for performing finishing by electrolytic dressing. 5. A continuation of the finishing taper surface,
5. The grinding device according to claim 4, wherein a tapered surface for discharging the workpiece is further formed on the outlet side of the workpiece.