JP2002001659A - Truing method and grinding device in plane grinding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a truing method and a grinding device capable of carrying out a highly accurate truing in a short time, in a plane grinding device. SOLUTION: In a plane grinding device 1 using a conductive grinding wheel 21, an electric discharge truing electrode 3 is disposed facing a circular grinding surface 21a of a grinding wheel 2 and is made a traverse movement in a range including the largest and smallest peripheral edges of the circular grinding surface 21a to carry out an electric discharge truing, when the velocity of the traverse movement of the electric discharge truing electrode 3 is controlled to keep constant a peripheral velocity of the circular grinding surface 21a facing the electrode 3, thereby achieving a uniform truing throughout the entire periphery of the circular grinding surface 21a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a truing method and a grinding device for a surface grinding device, and more particularly, to a surface grinding device using a conductive grindstone such as a metal bond diamond wheel using a discharge action. The present invention relates to a discharge truing technique for performing truing.

[0002]

2. Description of the Related Art In recent years, as one of the advanced precision processing techniques,
Attention has been paid to grinding technology using superabrasive grindstones.Particularly, diamond grindstones made by combining diamond abrasive grains with resin-based or metal-based bonding materials are the most suitable grindstones for grinding hard and brittle materials such as ceramics. It is preferably used.

In a surface grinding apparatus using such a superabrasive grindstone as a grinding wheel, truing of a grinding wheel is conventionally performed by the following method.

[0004] If a vertical double-ended surface grinder using a metal bond diamond grindstone is taken as an example of a grinding grindstone, the truing is performed as shown in FIG. A sharpening whetstone b for truing is inserted between a, and a bond (bonding material) B on the surface of the grinding whetstone is scraped off with loose abrasive grains of the whetstone whetstone b, and the abrasive grains A of the grinding whetstone are projected (dressing). While shaping the ground surface (truing).

That is, the truing of the superabrasive grindstone in the surface grinding apparatus has been performed by pressure working (lapping technique) using loose abrasive grains of the sharpening grindstone b as a tool.

[0006]

However, the conventional truing using such a wrapping technique has the following problems, and an improvement thereof has been desired.

That is, in the truing of the grinding wheel using the lapping technique, since the forming of the grinding wheel is performed by the grinding action of the free abrasive grains, the edge of the abrasive grain of the grinding wheel is worn, and the sharpness of the abrasive grains becomes dull. was there. Moreover,
In the case of such a lapping technique, there is also a problem that it takes a long time to form the grinding wheel.

In particular, in the truing of a double-ended surface grinder, as shown in FIG. 9B, if the balance of the pressure applied to the sharpening wheel b by the grinding wheels a during the truing is lost, Since the arm c supporting the grindstone b is bent, accurate molding is difficult, and there has been a problem that high-accuracy truing cannot be performed.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a truing method and a grinding apparatus capable of performing truing with high accuracy in a short time in a surface grinding apparatus. Is to do.

[0010]

In order to achieve the above object, a method for truing a conductive grinding wheel according to the present invention is a surface grinding apparatus for grinding a workpiece on an annular grinding surface of a rotationally driven grinding wheel. In the case where the annular ground surface is formed by a conductive grindstone in which abrasive grains are bonded by a conductive bonding material, the discharge truing electrode is disposed facing the annular ground surface, and the position of the discharge truing electrode is changed. Discharge truing is performed on the annular grinding surface while being traversed relative to the annular grinding surface.

That is, according to the present invention, in truing of a surface grinding apparatus, an electric discharge truing electrode is arranged facing an annular grinding surface of a grinding wheel, and the electric discharge truing electrode is relatively traversed along the annular grinding surface in the surface direction. By performing discharge truing while moving, truing is realized without contact with the ground surface of the surface grinding device. That is, in this method, discharge truing is performed while sliding one or both of the annular ground surface and the discharge truing electrode facing each other in the surface direction so that they do not contact each other. In addition, in addition to the grinding surface of a so-called cup-shaped grinding wheel,
A grinding surface of a disk-shaped grindstone having a recess in the center is included.

Therefore, according to this method, truing of the grinding wheel can be performed in a short time without damaging the cutting edge of the grinding wheel. In addition, since the discharge truing electrode performs the discharge truing without contacting the ground surface, it is possible to perform the truing with high precision even in the double-sided surface grinding apparatus.

In a preferred embodiment of the truing method, when the discharge truing electrode is traversed relative to the annular grinding surface, the discharge truing electrode is moved to the outermost peripheral edge of the annular grinding surface. And traverse movement within a range including the innermost peripheral edge.
Further, during the traverse movement, the traverse movement speed of the discharge truing electrode or the rotation speed of the grinding wheel is adjusted so that the removal amount per unit area of the annular grinding surface facing the discharge truing electrode is constant.

That is, by traversing the discharge truing electrode within a range including the outermost peripheral edge and the innermost peripheral edge of the annular ground surface, the entire surface of the annular ground surface can be trued. By maintaining a constant removal amount per unit area of the annular grinding surface facing the surface, uniform truing can be performed over the entire annular grinding surface.

In order to realize the above-mentioned truing method, the surface grinding device of the present invention is a surface grinding device provided with a grinding wheel using a conductive grinding wheel having abrasive grains bonded by a conductive bonding material. A discharge truing electrode disposed to face the annular grinding surface of the grinding wheel, and a truing electrode drive for traversing the discharge truing electrode within a range including the outermost peripheral edge and the innermost peripheral edge of the annular grinding surface. Means, and control means for controlling the traverse movement speed of the discharge truing electrode by the truing electrode driving means.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS.

FIG. 1 shows an example of a surface grinding apparatus according to the present invention. The surface grinding device 1 is a double-sided surface grinding device on the vertical axis, and is mainly composed of grinding wheels 2 and 2, a discharge truing electrode 3, a truing electrode driving means 4 and a control means 5. In the illustrated embodiment, the grinding wheels 2 and 2 are provided so as to be rotatable about an axis x of the grinding wheel shaft by grinding wheel driving means (not shown). Thereby, the cutting operation in the axial direction can be performed.

The grinding wheel 2 is provided with a conductive grinding wheel 21 in which abrasive grains are bonded by a conductive bonding material, and an annular grinding surface (annular grinding surface) is provided on an end surface of the conductive grinding wheel 21.
21a are formed. Specifically, for the conductive grindstone 21, for example, so-called superabrasive grains such as minute diamond abrasive grains and CBN (cubic boron nitride) abrasive grains are used as the abrasive grains A. A metal bond or a conductive resin bond containing a conductive substance is preferably used as the bonding material B of the abrasive grains A (see FIG. 5A for the state of the abrasive grains A and the bonding material B).

The grinding wheel 2 is electrically connected to the (+) pole of the DC power supply 7 through a power supply line 6a. Specifically, as shown in FIG. 1, a brush-like power supply 61a is provided at the end of the power supply line 6a.
The above-mentioned grindstone shaft is brought into contact with a in a rotatable state, so that direct-current power can be supplied to the grindstone wheel 2 (specifically, the conductive grindstone 21) via the grindstone shaft.

The discharge truing electrode 3 is an electrode for applying discharge truing to the annular ground surface 21a, and is electrically connected to the (-) pole of the DC power supply 7 through a power supply line 6b. ing. The discharge truing electrode 3 is an electrode (rotary electrode) having a narrow and small disk shape rotatably attached to a tip of a truing electrode driving means 4 described later (rotary electrode).
Cylindrical electrode surface 3 facing annular grinding surface 21a of grinding wheel 2
It is set to 1.

The truing electrode driving means 4 is shown in FIG.
As shown in FIG. 5, the apparatus is for traversing the discharge truing electrode 3 in a range including the outermost peripheral edge 21b and the innermost peripheral edge 21c of the annular grinding surface 21a. It has the structure shown in FIG.

The truing electrode driving means 4 is shown in FIG.
As shown in FIG. 5, a base 41, a swivel 42 provided on the base 41 so as to be rotatable via a swivel driving means (not shown), and an arm member fixedly mounted on the swivel 42 43 as a main part.

The rotating shaft 32 of the discharge truing electrode 3 is rotatably held at the tip of the arm member 43 via a bearing 431 (see FIG. 4). The discharge truing electrode 3 can be driven to rotate by being linked with the electrode rotation driving means 44 via a mechanism.

Specifically, in the present embodiment, the electrode rotation driving means 44 is constituted by an electric motor 441 fixedly provided on the swivel table 42, and the output shaft 442 of the motor 441 is connected to the arm member. A bearing 432 is provided on the base end side
Is held through. The pulley 32 serves as a power transmission mechanism on the rotation shaft 32 and the output shaft 442, respectively.
1, 443 are provided, which are linked by a belt 444.

A power supply 6 for connecting to the (-) pole of the DC power supply 7 is provided at the tip of the rotary shaft 32.
1b is provided so that a (-) voltage can be applied to the discharge truing electrode 3. Accordingly, a ceramic bearing is preferably used as the bearing 431 of the rotating shaft 32 from the viewpoint of preventing leakage.

The truing electrode driving means 4 has a coolant supply means 45 for supplying a coolant (coolant) for cooling the discharge truing electrode 3 during discharge truing, which will be described later. And a coolant removing means 46 for removing the used coolant.

The coolant supply means 45 includes a coolant supply source (not shown), a coolant outlet 451 provided at the tip of the arm member 43 facing the inner side surface of the discharge truing electrode 3, and a coolant supply connection connecting these. And a pipe 452. Further, the coolant pressurized and supplied from the coolant supply source is blown from the coolant outlet 451 to the inner surface of the discharge truing electrode 3 through the pipe 452.

On the other hand, the coolant removing means 46 is connected to the discharge truing electrode 3 by the coolant supply means 45.
This is a means for removing the coolant sprayed on the surface to secure electrical insulation between the cylindrical electrode surface 31 of the discharge truing electrode 3 and the annular grinding surface 21a of the conductive grindstone 21. The coolant is removed by air injection.

Specifically, the coolant removing means 46
Is composed of an air supply source (not shown), an air injection nozzle 461 provided at the tip of the arm member 43 so as to face the cylindrical electrode surface 31 of the discharge truing electrode 3, and an air supply pipe 462 for connecting these pipes. Be composed. Then, air pressurized and supplied from the air supply source is blown from the tip of the air injection nozzle 461 to the cylindrical electrode surface 31 of the discharge truing electrode 3 via the pipe 462,
Thereby, the coolant attached to the cylindrical electrode surface 31 is removed.

In the present embodiment, since the grinding device 1 is a double-sided surface grinding device having a vertical axis, the air injection nozzles 461 correspond to the number of the grinding wheels 2 as shown in FIG. An upper and lower pair is provided on the side surface of the arm member 43.
Further, since the air injection nozzle 461 is provided to secure electrical insulation between the discharge truing electrode 3 and the conductive grindstone 21 as described above, the air injection nozzle 461 is capable of injecting air into these gaps. The nozzle is mounted so that the air jet direction at the tip of the nozzle can be adjusted (see the two-dot chain line in FIG. 3). Further, the tip of the air injection nozzle 461 is connected to the coolant injection port 45.
The coolant supplied from the discharge truing electrode 3
Fig. 4
As shown in the figure, the eccentricity is provided slightly outside the center of the cylindrical electrode surface 31.

The control means 5 is a control center for controlling the operation of each part of the surface grinding apparatus 1, and is specifically constituted by a microcomputer storing a predetermined control program. That is, the control means 5 controls the operations of the grinding wheel driving means, the grinding wheel cutting driving means, the turning driving means, the electrode rotation driving means 44, and the like. In addition, the traverse movement (moving direction and moving speed) of the discharge truing electrode 3 and the application of voltage to the electrode, and the pressurizing operation of the coolant supply source and the air supply source can be controlled in association with each other. I have.

In the surface grinding apparatus 1 configured as described above, when the grinding wheel 2 is trued,
On-machine discharge truing of the grinding wheel 2 is performed by the control means 5 controlling the grinding wheel 2 and the discharge truing electrode 3 as described below.

A: Basic principle and basic operation of truing
Work First, when the start of the truing, the control means 5
Sets the interval between the grinding wheels 2 and 2 and the rotation speed of the grinding wheels 2 and 2 in a predetermined state,
The discharge truing electrode 3 is driven to rotate at a predetermined rotation speed.

In parallel with these processes, the control means 5 turns on the power of the DC power supply 7 and
2 and a predetermined voltage are applied to the discharge truing electrode 3.

When these processes are completed, the control means 5 operates the turning drive means of the turning table 42 to move the discharge truing electrode 3 from the outermost peripheral edge 21b of the annular grinding surface 21a to the outermost. The traverse movement is performed toward the inner peripheral edge 21c (see FIG. 2A).

At this time, (+) is applied to the annular grinding surface 21a.
Is applied to the discharge truing electrode 3 (−).
Is applied, the discharge truing electrode 3
As a result, a discharge action occurs between the two electrodes, whereby the metal bond B portion of the conductive grindstone 21 is dissolved and removed as shown in FIG. 5 (a), and the annular grinding surface 21a is newly formed. . In the present embodiment, the coolant injected from the coolant outlet 451 is in a mist state by the air injected from the air injection nozzle 461, and is interposed between the annular ground surface 21 a and the discharge truing electrode 3. Therefore, the discharge effect is increased.

The process of forming the annular ground surface 21a by the discharge action will be described in more detail. First, as shown in FIG. 6, the discharge truing electrode 3 is moved from the outermost end 21b to the innermost end of the annular ground 21a. The metal bond B on the surface of the annular grinding surface 21a is dissolved and removed by traversing the portion 21b (see FIG. 6A).

The traverse movement causes the discharge truing electrode 3 to move to the innermost end 2 of the annular ground surface 21a.
1c (see FIG. 6 (b)), a predetermined cutting operation is applied to the grinding wheels 2 and 2 to traverse the discharge truing electrode 3 again toward the outermost end 21b (FIG. 6). (c)).

The traverse movement of the discharge truing electrode 3 and the cutting operations of the grinding wheels 2 and 2 are repeated until the annular grinding surface 21a is formed into a desired shape.

As described above, according to the surface grinding apparatus 1 shown in the present embodiment, the truing of the grinding wheels 2 is performed by using the electric discharge truing technique.
Since the truing is performed in a non-contact manner, the truing of the double-sided surface grinding apparatus can be performed with high accuracy without bending the arm member 43 as shown in FIG. 5 (b).

B: Traverse Movement Speed Control As described above, in the surface grinding apparatus 1 of the present invention, the grinding wheels 2 and 2 are trued while the discharge truing electrode 3 is traversed along the annular grinding surface 21a. In the case where the rotation speeds of the grinding wheels 2 and 2 are maintained at a constant rotation speed, the discharge truing electrode 3 is traversed at a constant speed. Can not be trued.

For this reason, in the surface grinding apparatus 1 of the present embodiment, the control means 5 sets the following so that the circumferential velocity of the annular grinding surface 21a facing the discharge truing electrode 3 is almost constant during the traverse movement. The traverse movement speed is controlled as described above.

That is, in the present embodiment, the traverse movement of the discharge truing electrode 3 is realized by the rotational drive of the turning drive means.
In synchronization with the traverse movement of the discharge truing electrode 3,
The traverse speed is reduced when the discharge truing electrode 3 is located near the outer periphery of the annular grinding surface 21a, and is increased when the discharge truing electrode 3 is located near the inner periphery of the annular grinding surface 21a. Control for adjusting the rotation speed of the driving means is performed to keep the removal amount per unit area of the annular ground surface 21a facing the discharge truing electrode 3 constant.

In controlling the traverse movement speed, the rotation speed of the turning drive means is kept constant.
The rotation speed of the grinding wheel 2 may be adjusted in synchronization with the traverse movement of the discharge truing electrode 3.

As described above, in the present embodiment, the removal amount per unit area of the annular ground surface 21a facing the discharge truing electrode 3 during the traverse movement is made constant.
Since the traverse moving speed of the discharge truing electrode 3 or the rotation speed of the grinding wheel 2 is controlled, uniform truing is realized over the entire surface of the annular grinding surface 21a.

With respect to the control of the traverse movement speed, if the grinding wheel 2 to be trued has an irregularity (gap) on the annular grinding surface 21a due to a shape loss or the like, the above-mentioned traverse movement speed is controlled. With only the above control, it is necessary to repeatedly perform the above-described traverse movement to completely remove these gaps. Therefore, the control of the above-described traverse movement speed is desirably modified by the control means 5 as follows.

That is, in this case, the DC power supply 7
A discharge voltage detecting means (not shown) for detecting a discharge voltage during discharge truing is provided to detect the discharge voltage, and the traverse moving speed is corrected based on the discharge voltage.

Specifically, when the surface of the grinding wheel is projected, the discharge voltage is reduced, while when the surface of the grinding wheel is depressed, the discharge voltage is increased. If the surface is protruding, the traverse movement speed is slowed to remove the metal bond B at the protruding portion intensively, while if the whetstone surface is depressed, the traverse movement speed is increased to remove the metal bond B. Reduce the amount. In other words, by correcting the traverse movement speed according to the unevenness of the whetstone surface, repetition of the traverse movement of the discharge truing electrode 3 can be reduced, thereby realizing truing in a short time.

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, in the above-described embodiment, the case where the present invention is applied to a double-sided surface grinding machine having a vertical axis has been described. However, the present invention is not limited to the double-sided surface grinding apparatus having a vertical axis, and is shown in FIG. The present invention can be applied to such a double-sided surface grinding device having a horizontal axis, and further to a so-called single-headed surface grinding device as shown in FIG. In other words, the present invention can be applied to any type of surface grinding device as long as it performs discharge truing while relatively traversing the discharge truing electrode 3 along the annular grinding surface 21a of the surface grinding device 1. Applicable.

Further, in the above-described embodiment, the form of the rotary electrode which is rotationally driven is shown as the discharge truing electrode 3, but a fixed electrode which is not rotationally driven can be adopted as the discharge truing electrode.

Further, in the above-described embodiment, the case where the arm member 43 is swung to traverse the discharge truing electrode 3 has been described.
As shown in (b), the discharge truing electrode 3 can be traversed by moving the arm member 43 forward and backward.

In the above embodiment, the case where the discharge truing electrode 3 is slid when the discharge truing electrode 3 is traversed is described. However, the discharge truing can be performed by sliding the grinding wheel 2.

Further, in the above embodiment, the annular grinding surface 2
Although the case where 1a is flat is shown, by changing the cutting amount of the grinding wheel 2 in synchronization with the traverse movement of the discharge truing electrode 3, it is possible to truing to a shape as shown in FIG. 8, for example.

[0055]

As described in detail above, according to the present invention,
In the truing of a surface grinding device using a conductive grinding wheel, the discharge truing is performed while traversing the position of the discharge truing electrode relative to the annular grinding surface of the surface grinding device, so the time required for truing is conventionally reduced. It can be greatly shortened than truing using the lap technology.

Further, since the truing is performed without contact between the discharge truing electrode and the annular grinding surface, the abrasive grains of the grinding wheel do not wear and the sharpness of the abrasive grains is not dull. Can do it. In particular, in the truing of a double-sided surface grinding device, the distortion caused by the bending of the arm as in the conventional case can be eliminated, and more accurate truing can be realized.In addition, two grinding wheels can be trued simultaneously by one truing operation. Work time can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a vertical double-ended double-sided surface grinding apparatus to which a truing method of a conductive grindstone according to the present invention is applied.

FIG. 2 is an explanatory view showing a state of traverse movement of a discharge truing electrode in the surface grinding device.

FIG. 3 is a side view showing a schematic configuration of a truing electrode driving means for traversing a discharge truing electrode in the surface grinding apparatus.

FIG. 4 is a plan view showing a schematic configuration of the truing electrode driving means.

5A and 5B are explanatory views for explaining a method of truing a conductive grindstone according to the present invention. FIG. 5A shows the principle of electric discharge truing in a vertical double-ended surface grinding device, and FIG. The state of the arm member at the time of truing of the apparatus is shown.

FIG. 6 is an explanatory diagram showing an example of a process of electric discharge truing in the surface grinding device according to the working procedure.

FIG. 7 is an explanatory view showing an application example of a truing method of a conductive grindstone according to the present invention. FIG. 7 (a) shows an application example to a double-sided surface grinding device with a horizontal axis, and FIG. An example of application to a head surface grinding device is shown.

FIG. 8 is an explanatory view showing an example of forming a ground surface using the truing method.

9A and 9B are explanatory diagrams for explaining a truing method of a grinding wheel in a conventional surface grinding apparatus. FIG. 9A is an enlarged view showing a state of a grinding wheel at the time of truing, and FIG. 2 shows the state of the arm member that supports the dressing grindstone in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Surface grinding apparatus 2 Grinding wheel 21 Conductive grindstone 21a Annular grinding surface 3 Discharge truing electrode 31 Cylindrical electrode surface 4 Truing electrode drive means 41 Base 42 Swivel table 43 Arm member 45 Coolant supply means 451 Coolant ejection port 46 Coolant removal means 461 Air injection nozzle 5 Control means 6a, 6b Power supply line 61a, 61b Power supply 7 DC power supply device A Abrasive B Binding material

Claims (8)

[Claims] 1. A surface grinding apparatus for grinding a workpiece on an annular grinding surface of a rotationally driven grinding wheel, wherein the annular grinding surface is formed by a conductive grindstone having abrasive grains bonded by a conductive bonding material. In the formed one, the discharge truing electrode is disposed facing the annular grinding surface, and the discharge truing is performed on the annular grinding surface while traversing the position of the discharge truing electrode relatively to the annular grinding surface. A truing method for a surface grinding apparatus, comprising: 2. The truing method for a surface grinding apparatus according to claim 1, wherein the discharge truing electrode is traversed within a range including an outermost peripheral edge and an innermost peripheral edge of the annular grinding surface. . 3. The traverse movement speed of the discharge truing electrode or the rotation speed of the grinding wheel is adjusted so that the peripheral speed of the annular grinding surface facing the discharge truing electrode during the traverse movement is constant. The truing method for a surface grinding device according to claim 2, wherein 4. A surface grinding apparatus provided with a grinding wheel using a conductive grinding wheel having abrasive grains bonded by a conductive bonding material, comprising: a discharge truing electrode disposed to face an annular grinding surface of the grinding wheel; A truing electrode driving means for traversing the discharge truing electrode within a range including the outermost peripheral edge and the innermost peripheral edge of the annular ground surface; and controlling a traverse movement speed of the discharge truing electrode by the truing electrode driving means. A surface grinding apparatus, comprising: 5. The surface grinding apparatus according to claim 4, wherein the truing electrode driving means has a structure for rotating the discharge truing electrode along the annular grinding surface. 6. The surface grinding apparatus according to claim 4, wherein said truing electrode driving means has a structure for moving said discharge truing electrode forward and backward along said annular grinding surface. 7. The surface grinding apparatus according to claim 4, wherein the discharge truing electrode is in the form of a rotary electrode. 8. The apparatus according to claim 7, further comprising: means for injecting a coolant to a side surface of the rotary electrode; and means for injecting air toward a gap between the annular grinding surface and the rotary electrode. Surface grinding equipment.