JPH04256575A - Method using thereof dressing method for grinding wheel and grinding method using the same - Google Patents

Abstract

PURPOSE:To generate no deposit on the electrode opposed to a grinding wheel and on the grinding wheel and to execute a stabilized dressing, in the dressing of the grinding wheel that electrolysis is utilized. CONSTITUTION:Current is temporarily inversed, by providing an electrode 4 in opposition to a metal bond grinding wheel 1, flowing a grinding liquid 13 so as to interposing it between the electrode 4 and metal bond grinding wheel 1, flowing current in the specified direction between the electrode 4 and metal bond grinding wheel 1 and switching a switch 9.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sharpening a whetstone in which abrasive grains are held in a conductive binder by electrolytic action, and a grinding method using the same.

0002

2. Description of the Related Art Conventionally, as a method of highlighting a grindstone such as a metal bonded grindstone in which abrasive grains are held in a conductive binder, there is a method that utilizes electrolytic action. This method utilizes the fact that a grinding fluid obtained by diluting a water-soluble grinding fluid with water has weak conductivity, as described in JP-A-1-188266, for example. An electrolytic solution is used as an electrolytic solution, the conductive binder of the grinding wheel is used as one electrode, and the other electrode is provided opposite the grinding wheel to conduct electricity to the grinding liquid, and the bonding agent is dissolved by the electrolytic action at that time. This is a method of sharpening a whetstone.

0003

[Problems to be Solved by the Invention] However, in the conventional grinding wheel sharpening method described above, electrolyzed components and binders in the grinding fluid are deposited on the surface of the grinding wheel and on the electrode provided opposite the grinding wheel. This impedes the dissolution of the binder and reduces the conductivity of the electrode surface, which impedes sharpening and also poses a problem in the grinding process using this grindstone.

[0004] An object of the present invention is to provide a grindstone sharpening method that can perform stable sharpening by removing precipitates generated on a grindstone or an electrode facing the grindstone, and a grinding method using the same. There is a particular thing.

[0005]

[Means for Solving the Problems] A grindstone sharpening method of the present invention to achieve the above object includes the above-mentioned grindstone sharpening method in which a grindstone in which abrasive grains are held in a conductive binder is sharpened by electrolytic action. An electrode is provided opposite the grindstone, and a current is passed between the electrode and the grindstone by interposing a grinding fluid consisting of a water-soluble grinding oil and water, and the direction of the current is temporarily reversed. It is characterized by:

[0006] The current for sharpening the grindstone can have a waveform of a pulse train having components in the reverse direction at regular time intervals.

The current for sharpening the grindstone can have a waveform of a pulse train having a component in the reverse direction every cycle.

The grinding method of the present invention is for grinding a workpiece while sharpening a grindstone using the above-described grindstone sharpening method of the present invention.

[0009]

[Operation] Sharpening progresses by passing an electric current between the electrode and the grinding wheel, and by temporarily reversing this current, precipitates generated on the surface of the grinding wheel or on the electrode placed opposite the grinding wheel are removed. Dissolve and remove with grinding fluid.

[0010] The direction of the current flowing between the electrode and the grinding wheel during sharpening may be such that the binder in the grinding wheel is dissolved by electrolytic action. The electrode may be made negative.

[0011]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of the configuration of a grinding system used to carry out the grindstone sharpening method of the present invention.

The metal bonded grindstone 1 for grinding has a short cylindrical shape, and its peripheral surface is a grindstone portion 1a made of a metal bond and abrasive grains. Further, the portion of the metal bond grindstone 1 other than the grindstone portion 1a is a support body 1b made of metal, and the metal bond grindstone 1 is rotatably rotated in the direction of the arrow shown in the figure by a rotating shaft (not shown) attached to the support body 1b. supported.

A workpiece 6 to be ground is provided below the metal bond grindstone 1 so as to be in contact with the grindstone portion 1a. The workpiece 6 can be made of any industrial material such as metal, glass, or ceramics, and can be cut and moved relative to the metal bond grindstone 1 by the table 7.

An electrode 4 is provided above the metal bonded grindstone 1 so as to face the grindstone portion 1a with a gap therebetween. The interval between the gaps is adjusted as appropriate depending on the material of the binder of the metal bond grinding wheel 1, the grinding fluid, the rated voltage of the DC pulse power source 5, which will be described later, and the like.
It is about 1 mm. As the material of the electrode 4, for example, copper or the like can be used.

The positive electrode of the DC pulse power source 5 is connected to the metal bond grinding wheel 1 through the contact a of the switch 9, which is a double switch.
is switchably connected to the power supply brush 3 in contact with the support 1b of the switch 9 or to the electrode 4 via the contact b of the switch 9, while the negative electrode of the DC pulse power source 5 is connected to the contact b of the switch 9. It is configured to be switchably connected to the electrode 4 via the contact point b of the switch 9, or to the power supply brush 3 via the contact point c of the switch 9. Since the support body 1b is made of metal, the grinding wheel portion 1a of the metal bond grinding wheel 1
A positive or negative voltage will be applied to the bonding agent made of metal. As the DC pulse power source 5, (B) in FIG.
It is possible to output a pulse train current as shown in Figure 2. For example, the voltage and current when on are about 70V and 20A to 15V, respectively.
The voltage is about 0V and 0.3A, and the voltage is turned on for only several microseconds to several tens of microseconds at intervals of several microseconds to several tens of microseconds.

A grinding liquid 13 for dissipating the heat generated during the grinding process and performing the grinding process smoothly is stored in a water tank 2 and supplied to a conduit 10 by a circulation pump 8, which is provided at the tip of the conduit 10. It is designed to eject from two nozzles 11. One of the two nozzles 11 is provided close to the metal bond grinding wheel 1 so as to supply the grinding liquid 13 to the point where the metal bond grinding wheel 1 and the workpiece 6 come into contact (grinding point), and the other The nozzle 11 is provided close to the metal bond grindstone 1 so as to supply the grinding liquid to the gap between the metal bond grindstone 1 and the electrode 6. The grinding liquid 13 spouted from the nozzle 11 is sent to the water collection pan 1.
2 and returned to tank 2.

The grinding fluid 13 is preferably a water-soluble grinding fluid diluted with pure water, and the anion concentration is adjusted by adding an electrolyte. As the pure water, normal ion exchange water can be used. Moreover, the electrolyte here refers to something that dissolves in water and dissociates into anions and cations, and the anion concentration can be controlled by controlling its concentration. In addition, almost the same effect is observed with water-insoluble grinding fluids, such as emulsion types, and even when diluted with city water and without the addition of electrolytes, there may be some differences depending on the time and location of city water sampling. However, it has almost the same effect.

The concentration of the electrolyte added to the grinding fluid 13 is appropriately selected depending on the type of metal bond grinding wheel 1, the voltage applied between the metal bond grinding wheel 1 and the electrode 4, the material of the workpiece 6, the grinding conditions, etc. For example, when hydrochloric acid is used as an electrolyte, the weight concentration of the grinding fluid is 1
It is preferably 0 ppm or more and several hundred ppm or less. If the electrolyte concentration is too high, problems such as corrosion may occur.

Next, the operation of this embodiment will be explained.

First, the circulation pump 8 is activated, and the grinding fluid 13 is jetted out from each nozzle 11. Next, the metal bond grindstone 1 is rotationally driven by a drive means (not shown),
Grinding of the workpiece 6 is started. At the same time, the positive electrode of the DC pulse power source 5 is applied to the contact a of the switch 9, and the negative electrode of the DC pulse power source 5 is applied to the contact b of the switch 9, so that the electrode 4 becomes negative and the metal bond grindstone 1 becomes positive. A DC pulse current from the DC pulse power source 5 is applied as shown in FIG. At this time, since the grinding liquid 13 is supplied to the gap between the metal bond grinding wheel 1 and the electrode 4, the metal bonding agent of the metal bond grinding wheel 1 is the anode, the electrode 4 is the cathode, and the grinding liquid 13 is supplied to the gap between the metal bond grinding wheel 1 and the electrode 4. Electrolysis to form an electrolytic solution is started. Then, the anions of the grinding liquid 13 attack the anode, that is, the binder, and the metal constituting the binder dissolves in the grinding liquid, while the abrasive grains are generally made of diamond, silicon carbide, alumina, etc. Since it is made of electrically insulating material, the abrasive grains will not dissolve. Therefore, only the binder is dissolved, and the metal bond grindstone 1 is sharpened.

FIG. 2 shows the progress of the sharpening described above.

In FIG. 2, the grindstone portion 1a of the metal bond grindstone 1 is depicted as having abrasive grains 22 dispersed in a binder 21 made of an n-valent metal. When a negative voltage is applied to the electrode 4 and a positive voltage is applied to the binder 21, electrons are emitted from the electrode 4 into the grinding liquid 13, anions in the grinding liquid are attracted to the binder 21, and hydrogen ions are attracted to the electrode 4. The metal constituting the binder 21 dissolves in the grinding fluid 13.

The dissolved metal forms a first precipitate 21a on the surface of the electrode 4, and the grinding fluid 13 is electrolyzed to form a second precipitate 13a on the surface of the binder 21, forming a second precipitate 13a on the surface of the electrode 4. A third precipitate 13b is generated on the surface of each. These precipitates 21a, 13a, 13b are formed on the electrode 4, respectively.
If the conductivity is lower than that of the binder 21, it will be difficult for the current that generates the electrolytic action to flow and the progress of sharpening will be hindered. , as the amount of production increases as the sharpening progresses,
The abrasive grains 22 no longer protrude outside the whetstone portion 1a, and no sharpening is performed.

Therefore, each precipitate 21a, 13a, 13b
As shown in FIG. 1, before a large amount of
The negative electrodes of the electrodes are switched to the contact c side of the switch 9 to reverse the polarity, and a DC pulse current from the DC pulse power source 5 is applied so that the electrode 4 is positive and the metal bond grindstone 1 is negative.

At this time, as shown in FIG. 3, electrolytic action occurs in the direction opposite to that shown in FIG. 2, and each precipitate 21a, 1
3a and 13b are dissolved and together with the grinding liquid, the water collection pan 1
2 (see Figure 1). Thereafter, by returning the switch 9 to the original position and further advancing the sharpening shown in FIG. 2, the amount of protrusion of the abrasive grains 22 from the grindstone portion 1a increases, and sufficient sharpening is performed.

In this embodiment, the DC pulse power source 5 is provided with a switch 9, but instead of this, as shown in FIG. 5, a pulse whose polarity is inverted at regular time intervals may be generated. In this case, by making it possible to input and change the period, polarity reversal time, etc. as data, switching by a switch becomes unnecessary, and continuous grinding processing can be automated and unmanned.

Alternatively, instead of the DC pulse power source 5, as shown in FIG. good.

Next, the results of experiments conducted on the embodiment shown in FIG. 1 will be explained.

(Experiment example) Straight type #1200 cast iron bond diamond grindstone (SD12
00N75FA, φ100mm, width 3mm),
For optical glass (BK7, width 16 mm, length 90 mm), grinding wheel peripheral speed 1500 m/min, depth of cut 30 μm,
Feed speed 2mm/sec, pulse on time 5μsec
, pulse off time 5 μsec, pulse peak current value 1
Under each electrolytic condition of 0 A (setting value) and a pulse peak voltage of 70 V (setting value), surface grinding was performed while repeating the operations of sharpening for 120 minutes and polarity reversal for 1 minute. The electrolytic conditions at the time of polarity reversal were the same as the electrolytic conditions at the time of polishing. In addition, as a grinding fluid, water-soluble Noritake AFG-M (manufactured by Noritake Co., Ltd., conductivity approximately 2.4
mS/cm) was diluted 50 times, and the flow rate was 6000cm3/
I ran it at min.

The results are shown by the solid line in FIG. As is clear from these results, the dressing current value I gradually decreases from the start of dressing, the grinding resistance thrust force FN gradually increases, and the dressing current value I becomes approximately half in the cumulative grinding time of 120 minutes. The grinding resistance thrust force FN began to increase significantly. At this point, when the polarity was reversed for 1 minute, the dressing current value I and the grinding resistance thrust force FN each recovered to almost the same state as at the start of dressing. It recovered in the same way when grinding was continued for another 120 minutes, that is, when the cumulative grinding time was 240 minutes, and it recovered in the same way when the cumulative grinding time was 360 minutes. The finished surface roughness of the workpiece to be ground did not change significantly, and no deterioration in grinding quality was observed.

(Comparative Example) Surface grinding was carried out under the same conditions as in the above experimental example except that polarity reversal was not performed.
As shown by the dotted line in Fig. 4, the sharpening current value I continues to decrease even after being approximately halved at the cumulative grinding time of 120 minutes, and the grinding resistance thrust force FN increases significantly, and the cumulative grinding time is 13 minutes.
At 0 minutes, a change called grinding burn occurred in which the surface of the workpiece to be ground was oxidized by the heat generated by the grinding process, and the finished surface roughness significantly deteriorated.

[0033] In this experimental example, the sharpening time was 120 minutes.
Although the polarity reversal time was set to 1 minute, these values are appropriately determined depending on the processing conditions, the material of the workpiece to be ground, the type and shape of the grindstone, etc.

[0034]

[Effects of the Invention] Since the present invention is constructed as described above, it has the following effects.

According to the grinding wheel sharpening method of the present invention, generated precipitates are removed, the conductive binder of the grinding wheel is continuously dissolved over a long period of time, and the grinding wheel is well sharpened. Processing stability can be improved.

Therefore, according to the grinding method of the present invention, grinding can be carried out continuously over a long period of time, improving productivity.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the configuration of a grinding system used to carry out the grindstone sharpening method of the present invention.

FIG. 2 is an explanatory diagram showing a situation when a normal sharpening current is applied to the grinding apparatus shown in FIG. 1;

FIG. 3 is an explanatory diagram showing a situation when the current is temporarily reversed in the grinding apparatus shown in FIG. 1;

FIG. 4 is a graph showing the sharpening current value and grinding resistance thrust force according to the present example.

FIG. 5 is a waveform diagram showing an example of a pulse train having components in the reverse direction at constant time intervals.

FIG. 6 shows an example of a pulse train, and (A) is a waveform diagram showing an example of a pulse train having a component in the reverse direction for each cycle;
B) is a waveform diagram showing an example of a DC pulse train.

[Explanation of symbols]

1 Metal bond grinding wheel 1a Grinding wheel portion 1b Support body 2 Water tank 3 Power supply brush 4 Electrode 5 DC pulse power source 6 Workpiece 7 Table 8 Circulation pump 9 Switch 10 Conduit 11 Nozzle 12 Water collection pan 13 Grinding liquid 13a, 13b, 21a Precipitate 21 Binder 22 Abrasive grain

Claims (4)

[Claims] 1. A grindstone sharpening method in which a grindstone in which abrasive grains are held in a conductive binder is sharpened by electrolytic action, in which an electrode is provided opposite to the grindstone, and a grinding process is performed between the electrode and the grindstone. A method for sharpening a grindstone, characterized in that a grinding liquid consisting of an oil agent and water is allowed to flow, a current is passed in a predetermined direction between the electrode and the grindstone, and the current is temporarily reversed. A method for sharpening a whetstone. 2. The grindstone sharpening method according to claim 1, wherein the current for sharpening the grindstone has a waveform of a pulse train having components in a reverse direction at regular time intervals. 3. The grindstone sharpening method according to claim 1, wherein the current for sharpening the grindstone has a waveform of a pulse train having a component in a reverse direction every cycle. 4. A grinding method for grinding a workpiece while sharpening a grindstone using the grindstone sharpening method according to claim 1, 2, or 3.