JPH02218554A - Inprocess electrolytic dressing method by plural electrodes - Google Patents

Abstract

PURPOSE:To easily perform the dressing keeping the balance of the depth and width in carving by smoothly carving the wide face of a grindstone base ground, by feeding a conductive work liquid while impressing an AC voltage, flowing an AC current between a grindstone and an electrode, and eluding the base ground of the grindstone by electrolyzing. CONSTITUTION:In dressing a conductive grindstone 3 while working a work 1 by this grindstone 3, a pair of electrodes 5a, 5b are arranged at a desired insulation distance and opposed to the grindstone face at a necessary gap. A conductive work liquid is then fed by a feeding means 8 between the electrode and grindstone face while impressing an AC voltage to a part between the electrodes 5a, 5b. Thus an AC current is flowed between the grindstone 3 and electrodes 5a, 5b, the grindstone 3 base ground is electrolytically eluded and the grindstone 3 peripheral face is subjected to dressing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an in-process electrolytic dressing method using multiple electrodes.

[Conventional technology and its technical issues]

BACKGROUND ART Grinding using various metal bond grindstones including cast iron bond grindstones is widely used as a method for shaping and finishing various materials including difficult-to-process materials such as ceramics and cemented carbide.

In this type of grinding process, the metal bonded grindstone has a tendency to become dull, so it is essential to dress it to maintain its sharpness.In-process dressing (on-machine dressing) is being attempted. Representative examples include:
There is a method (physical method) that uses a grinding fluid mixed with GC or WA abrasive grains that are finer than the abrasive grain size of the grinding wheel, but if the workpiece material or finished surface roughness is not determined, it is necessary to adjust the mixed grain size one by one. There is a hassle of having to change it. Another method is an electrical dressing method such as a discharge dressing method, but in this case there is a problem in that the power supply to the grindstone that rotates at high speed is difficult.

As a countermeasure to this problem, an electric discharge machining method using a pair of electrodes is proposed in Japanese Patent Laid-Open No. 62-39175. However, in this method, due to the processing principle, the gap between the grindstone and the electrode is set to 0.
01 ■, and delicate servo control must be performed according to the wear and tear of the electrode, resulting in poor workability and operability.The small gap also causes grinding debris to adhere to the grinding wheel surface, causing the band to rotate simultaneously. There is a risk of damaging the electrode and the stability of the dressing is likely to be impaired if The problem is that the amount of the abrasive grains is low, and the amount of protrusion of the abrasive grains tends to increase unnecessarily by carving deeply into the base material. Furthermore, it is necessary to use a special power supply device, resulting in an increase in device cost.

The present invention was developed through research to solve the above rDJM problem, and its purpose is not only to eliminate the need for power supply by brushes, but also to make metal bond grinding wheels extremely simple, reliable, and Can be stably in-process dressed.

It is an object of the present invention to provide an in-process dressing method using multiple electrodes of this kind, which allows the power supply device to be extremely inexpensive.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a method for dressing a workpiece while processing it with a conductive grindstone, comprising:
By using at least a pair of electrodes arranged with a required distance between the insulation parts, by arranging the electrodes to face the conductive grinding wheel surface with the required gap, and supplying the conductive machining fluid while applying an alternating voltage, This method involves passing an alternating current between the whetstone and the current, thereby electrolytically eluting the whetstone matrix.

The present invention will be explained below based on the accompanying drawings.

1 and 2 show the principle of the dressing method using multiple electrodes according to the present invention.

1 is a work mounted on a work table 2, 3 is a conductive grinding wheel, generally a metal bonded grinding wheel; in this example, a straight grinding wheel is used, and 64 is designed to be rotated at high speed by a main shaft. This is an electrolytic dressing device used in the present invention, which consists of one to three or more electrodes 5a, 5b and an insulating material that is supported at a required distance @L to prevent electrolysis from occurring between them. It includes a support 6 and a power supply means 7 for applying an electrolytic current to the electrodes 5a and 5b.

The support body 6 is attached to the device main body (not shown), and is combined with an arbitrary adjustment means 11 such as a screw type, so that a required gap Q, for example, Q=0, is established between the end surfaces 50 of the electrodes 5a, 5b and the grinding wheel surface 30. It is designed to form .03 to 0.07 m5.

8 is means for supplying a machining liquid having appropriate conductivity between the end faces 50 of the electrodes 5a, 5b and the grindstone surface 30, and 9 is means for supplying a machining liquid between the workpiece 1 and the grindstone 3.

The electrodes 5a and 5b are preferably made of graphite, and are processed into a shape that corresponds to the shape of the grinding wheel, and do not require any special power supply device as the power supply for the power supply means 7, and are powered by alternating current (single-phase alternating current). , 3-phase AC) or other commercial power sources are sufficient. This is because when direct current is used, electrolytic products adhere to one electrode and are removed by electrolysis from the other, resulting in an excessively wide gap between the electrodes. For example, the power supply circuit may be configured by inserting a transformer 12 so as to float it from the ground of the grinding wheel 3 and the machine body, and supplying power from the secondary side, and preferably in order to adjust the electrolytic current and prevent overcurrent in the event of a short circuit between the grinding wheel and the electrode. Variable resistance 13
intervene. Furthermore, an inverter may be inserted between the power source and the primary side of the transformer 12 if necessary, thereby making it possible to vary the frequency of the electrolytic current over a wide range.

In the present invention, while grinding the workpiece 1 with the grindstone 3 as shown in FIG. An AC electrolytic voltage is applied to the electrodes 5a and 5b by the power supply means 7 while supplying the conductive working fluid. As a result, the electrolytic current flows through the machining fluid to the electrodes 5a, 3a, and 5b, so that the base material forming the grindstone is electrolytically eluted and the abrasive grains protrude without power being supplied by the brush.

In this case, the electrolytic elution is performed not locally but over a wide area at once, and therefore the matrix is not carved more than necessary, and the matrix is kept smooth.

Since the gap between the electrode surface and the grinding wheel surface may be large,
There is no need for delicate adjustment operations, and it is sufficient to advance the support body 6 by a very simple method such as screw feeding. Furthermore, since the gap between the grinding wheel surface and the electrode can be increased, collisions with the electrode caused by rotation of grinding debris and vibrations can be avoided, and stable dressing can be performed without trouble.

Note that the present invention is not only applicable to straight whetstones, but also
It can be easily applied to other grindstones. FIG. 3 shows an example of application to a cup grindstone. In this case, the electrodes 5a and 5b are plate-shaped, for example, and are arranged so as to cross the flat grindstone 3 constituting the cupro end. FIG. 4 shows an example of application to a lapping grindstone, in which the workpiece 1 is placed on a disc-shaped lapping surface 30' and a predetermined pressing force is applied.

The electrodes 5a and 5b are plate-shaped or rod-shaped, and are arranged in a relationship that crosses the lapped surface 30'.

〔Example〕

Next, examples of the present invention will be shown.

■00 Applied to dressing during grinding using the straight grindstone of the present invention. The grinding device is a surface grinder, the grindstone is a cast iron bonded diamond grindstone (φ200I1 width 10111I1 grain size #120, concentration 100), and the workpiece is silicon nitride (Hvl 700), titanium diboride (Hv2700).
) and cemented carbide (HVlooO).

A pair of electrodes made of graphite are used, and each electrode has a maximum length of 55 m, an arc of 50 m, a height of 40 cm, and a thickness of 18 m.
, the opposing area per unit width of each electrode was 50 mm''/m, these electrodes were attached to an insulating material at intervals of 60 mm, and the gap a with the grinding wheel surface was set to 0.05 m using screws. Applied voltage E.

= 50V, electric current Ip = 25A. As the machining fluid, a low resistivity grinding fluid with a resistivity ρ=7oOΩ−1 was used.

■ Grinding of silicon nitride Grinding speed 1000 m/a+in, feed f = 12
m / l5in, grinding width W = 10mm, depth of cut Z = 10pm and 20um, and the results of alternate grinding with UP-DOWN are compared with normal grinding without in-process dressing (denoted as no ID). It is shown in Figure 5.

In normal grinding, gradually Z = 10μ■, Z = 20μ
However, according to the present invention, although the resistance increases slightly in the initial stage of grinding, the amount of grinding R=
After 350 ++ m'', it is stable, and it can be seen that the sharpness of the whetstone can be maintained appropriately.

Ill, 2 Grinding of titanium poride Grinding speed V-= 2000 m/win, feed f=12
The grinding was carried out under the conditions of m/m111 and grinding width W=5 m. The results are shown in Fig. 6. From this Fig. 6, the depth of cut is Z = 20.
When the μ layer becomes large, the grinding resistance (FV) increases rapidly in normal grinding, and at the time of R=1000+m'/m, Fv==
It reached about 26 kg f/m. However, when the present invention is applied, Fv is approximately l Q kg f / rr
In addition to being stable at m, the grinding ratio increased by about 70%, and 0R
It became =122.

This FIG. 6 also shows the actual peak current value Ir.
Gradually decreasing means that the gap between the grinding wheel and the electrode is increasing, that is, the amount of protrusion of the abrasive grains is increasing.

(2) Grinding of cemented carbide Grinding was carried out under the same conditions as for titanium uride. The results are shown in Figure 7. In this case, when the depth of cut is Z = 10μ, the grinding resistance during normal grinding increases rapidly, but according to the present invention, the sharpness remains stable at about 5 kg f / m. There is.

〔Effect of the invention〕

According to the present invention as described above, the twin electrode system eliminates the need for power supply using a brush, and in addition, excellent effects such as the first order can be obtained.

■Reducing and stabilizing grinding resistance when machining difficult-to-process materials can be easily achieved without making delicate adjustments.

■Since the gap between the electrode and the grinding wheel can be set wide, troubles such as damage to the electrode due to vibration of the electrode or entrainment of grinding debris can be prevented, resulting in better stability of dressing work.

■Dressing is done by electrolytic elution, and since the wide surface of the whetstone is ground gently, it is easy to achieve a dressing effect with a good balance between engraving depth and width.

■The power supply device is extremely inexpensive, and there are no restrictions on the grindstones that can be used, making it highly versatile.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an overview of the present invention, Fig. 2 is an enlarged view also showing the power supply method of the present invention, Figs. 3 and 4 are perspective views showing application examples of the present invention, and Figs. FIG. 7 is a graph showing the relationship between the amount of grinding and normal grinding resistance according to the present invention and conventional grinding.

Claims (2)

[Claims] (1) A method of dressing a workpiece while it is being processed with a conductive grindstone, using at least one pair of electrodes arranged with a required distance between the insulators, and separating the electrodes from the surface of the conductive grindstone with the required gap. A plurality of electrodes characterized in that an alternating current is caused to flow between the grinding wheel and the electrode by making them face each other while applying an alternating voltage and supplying a conductive working fluid, thereby electrolytically dissolving the grinding wheel matrix. In-process electrolytic dressing method. (2) The in-process electrolytic dressing method using multiple electrodes according to claim 1, wherein the electrodes are made of graphite and a gap of 3/100 or more is provided between the electrodes and the grinding wheel surface.