KR20020032459A - grinding machine with variable pulse power - Google Patents

Abstract

PURPOSE: A variable pulse type grinding machine is provided to improve machining quality through controlling local discharge of ground material, dressing amounts of grinder and electrode output by varying size, width and polarity of supplied power. CONSTITUTION: A variable pulse type grinding machine includes a conductive grinder consisting of metal bonding material where one electrode is provided by supply brush and around which another electrode is installed. Conductive grinding lubricant is supplied between the grinder and another electrode. Electric power is applied to the grinder and another electrode, thereby implementing electrolytic dressing. The grinding machine comprises a DC converter(10) for converting AC into DC, a DCDC inverter(30) for inverting output of DC converter into DC, a DC pulse generator(40) for converting output of DCDC inverter into pulse row, and a controller(70) for controlling output of DCDC inverter and pulse of DC converter.

Description

Grinding machine with variable pulse power

The present invention relates to an electrolytic power supply for grinding, wherein one electrode is supplied to the conductive grindstone side of the metal binder by a brush for feeding, and the other electrode is installed in proximity to one side of the peripheral surface of the grindstone. In the grinding processing apparatus, the conductive grinding liquid is supplied between the electrode and the other electrode, and the electrolytic dressing is applied by applying power to the grindstone and the other electrode, the DC converter for converting AC into DC, and the output of the DC converter. DC / DC converter for DC / DC conversion of unit power factor by ZCS switching method, DC pulse generator for converting output of unit power factor converter into pulse train, and output size of DC / DC converter by control signal of external input device And a control unit for controlling the pulse of the DC pulse generator. Column relates to a variable pulsed grinding machine including a power supply, characterized in that the output.

In particular, the power supply device is supplied with a pause (0) pulse supply control and a reverse (-) polarity pulse to intermittently supply a pause (0) pulse to a continuous positive (+) pulse train, the size of the pulse train is The pulse that is controlled by the control unit to have a target voltage (V) and a half target voltage (V) is variable control to the size of V, 1 / 2V, 0, -V, -1 / 2V It is a variable pulse grinding machine.

In general, in the grinding process using a metal binder grindstone, the workpiece is ground by rotating the grindstone. At this time, a loading phenomenon occurs on the surface of the grindstone, which makes it difficult to maintain a uniform grinding function. The use of the whetstone was almost impossible.

In order to solve the above problems, the protruding state of the grindstone particles is continuously maintained during the grinding process by combining the electrolytic dressing method with the grinding process using the metal binder grindstone, thereby preventing the clogging phenomenon of the grindstone during the grinding process. I solved it.

The apparatus and processing method related to the electrolytic dressing method of the prior art are as follows.

Fig. 7 is a perspective view of the device schematically shown in order to realize the electrolytic dressing method of grinding using a conventional metal grindstone grinding wheel.

Fig. 7 shows a conductive grindstone made of metal as a binder, which is usually composed of diamond particles or boron nitride particles bonded to a metal binder, or silicon carbide. Or aluminum oxide particles are bonded to the metal binder (metal).

On the other hand, the + electrode 2a is supplied to the conductive grindstone 1 configured as described above by the feeding brush 2, and the one side of the grindstone 1 is adjacent to the grindstone 1-the electrode 2b. Is provided, and the grinding liquid supply nozzle 3 to which the conductive grinding liquid is supplied is provided between the grindstone 1 and the electrode 2b.

The + and − electrodes 2a and 2b are supplied with a DC voltage having a pulse waveform from the external power supply 4.

At this time, the electroconductive grinding liquid uses the water-soluble oil equivalent to W2 type of KS standard, and conventional W3 type.

Looking at the effect of the prior art in detail as follows.

First, in the case of planar grinding using a straight grindstone, the workpiece 12 to be ground is first fixed on the workbench 11 to reciprocate from side to side, and then the grinding wheel 1 is rotated to grind the workpiece 12. At this time (at the time of grinding), the grinding fluid is supplied while grinding fluid is supplied from the grinding fluid supply nozzle 13 to cool the grinding part, which is ground in the same manner as a known method (see FIG. 1). .

On the other hand, when grinding the workpiece 12 while the grinding wheel 1 rotates in this way, the grinding stone particles 1a (for example, diamond or fluorine nitride particles, or silicon carbide and aluminum oxide particles) protruding from the surface of the grinding stone 1 ), The clogging of the whetstone (1) occurs, and the conductive grinding fluid is supplied through the grinding fluid supply nozzle (3) installed between the whetstone (1) and the electrode (2b) and at the same time the positive electrode ( When a voltage is applied through the power supply device 4 between 2a and 2b, the metal binder portion of the surface of the conductive grindstone 1 applied to + is eluted by electrolysis, and the grindstone particles are relatively released by such dissolution. Grinding is performed as the state (1a) protrudes.

Therefore, the grinding is performed in a state where the particles of the grindstone 1 itself protrude to the surface at all times by electrolytic dressing, so that the grinding efficiency is improved.

That is, in summary, the conductive grinding fluid is supplied during grinding, and the positive electrode pulse voltage is applied through the power supply 4 between the electrodes 2a and 2b to electrolytically dress the surface of the grindstone 1. As the electrolytic dressing is continuously carried out during the grinding process, the workpiece is ground while the grindstone particles 1a are always protruding to the surface, so that clogging of the grindstone 1 is eliminated, and the conventional mechanical There is an advantage that the consumption of the grinding wheel due to excessive dressing that occurs during dressing by the method can be prevented to extend the life of the grindstone (1).

However, according to the prior art method, the dressing efficiency has a great influence on the grinding efficiency or the precision grinding process. In the case of the prior art electrolytic dressing, the impurities generated at the negative electrode are caused by the electrolytic dressing by the direct current pulse. There was a problem in that it was not suitable for grinding ultra-precision mirror products due to the lack of scale and local discharge phenomenon.

Looking at the behavior of the electrolytic dressing in order to address the above problems, in the initial dressing, the surface of the grindstone is electrically conducting by the metal binder in the initiator, the electrical conductivity is good.

Therefore, the electrolytic current flowing through the grindstone surface has a maximum value and the potential difference between the grindstone and the cathode has a minimum value.

The metal binder is eluted by the continuation of electrolysis, and most of the metal binder is ionized with Fe 2+, and the ionized Fe is combined with the hydroxyl group OH— generated during electrolysis to form a hydroxide Fe (OH) 2 or Fe (OH). 3).

These materials are converted to oxides such as Fe2O3, forming an insulator coating on the grindstone surface at the end of the initial dressing.

By this electrochemical behavior, when the initial dressing is finished, the electrical conductivity of the whetstone surface decreases with the growth of the non-conductive coating, so that the electrolytic current is reduced and the potential difference between the whetstone and the cathode increases.

When the grinding is performed after the initial dressing, as the protruding grindstone particles wear, the non-conductive coating is also thinned at the same time, so that the electrical conductivity of the grindstone surface is increased again.

As a result, electrolysis is promoted, and the non-conductive coating is regenerated again.

In general, look at the dressing of the grindstone according to the power supply type of the electrolytic power supply, the surface of the grindstone is eluted when the positive power is supplied, the electrode is eluted when the negative power is applied.

Therefore, if alternating current is used as the power source for the electrolytic power supply, the surface of the grindstone and the electrode are eluted at the same time, and the distance between the poles decreases, thereby greatly reducing the electrolytic efficiency.

In the case of direct current, the unilateral electrolysis of the whetstone is generated, and the amount of the whetstone is significantly increased. In the case of the DC pulse wave method used to control the increase, the amount of the whetstone is controlled. Therefore, a considerable amount of impurities adhere to the electrode.

The output of the power supply device in the prior art described above is divided into a direct current or a direct current pulse wave.

However, in the case of the direct current method, the unilateral electrolysis of the whetstone is generated, and the amount of the whetstone is significantly increased. In the case of the direct current pulse wave, the amount of the whetstone is controlled, but the amount of the whetstone is controlled. There is a problem in that impurity adhesion and local discharge phenomenon occur.

In other words, during dressing of the grindstone, impurities attached to the electrode increase, which hinders the flow of current, which hinders the electrolytic process of the grindstone.In severe cases, the grindstone particles are embedded to prevent the sharp particles from protruding and automation is impossible. There is a problem to let.

In order to solve the above problems, an object of the present invention is to provide an apparatus in which a process of removing impurities attached to an electrode is performed while supplying power to which a whetstone is delivered.

It is also an object of the present invention to provide a device that can change the power supply characteristics in order to increase the efficiency of the grindstone electrolysis process.

1 is a power supply circuit block diagram of a variable pulse grinding machine according to the present invention;

2 is a circuit diagram of a power supply DC output unit of a variable pulse grinding apparatus according to the present invention.

Figure 3 is a mode of operation of the power supply DC / DC converter of the variable pulse grinding machine according to the present invention

4 is a circuit diagram of a power supply DC pulse generator of a variable pulse grinding apparatus according to the present invention.

Fig. 5 is a perspective view of a device schematically shown in order to realize the electrolytic dressing method of grinding using a conventional metal grindstone grindstone;

* Explanation of symbols on main parts of drawings *

10: DC converter 30: DC / DC converter

40: DC pulse generator 70: control unit

The present invention has been made in order to achieve the above object, the one side electrode is supplied to the conductive grindstone side of the metal binder by a brush for feeding, and the other electrode is installed close to one side of the peripheral surface of the grindstone, between the grindstone and the other electrode In the grinding processing power supply device which supplies electroconductive grinding liquid and supplies electric power to the grindstone and the other electrode to perform electrolytic dressing, a DC converter for converting AC into DC and ZCS switching technique for outputting the DC converter DC / DC converter for converting unit power factor into DC / DC converter, DC pulse generator for converting output of unit power factor converter into pulse train, and output size and DC pulse of the DC / DC converter by control signal of external input device. Consists of a control unit that controls the pulse of the generator, the power is variable in size, width, and polarity It is a technical gist of a grinding power supply characterized in that the power.

Here, the power supply device is supplied with a pause (0) pulse supply control and a reverse (-) polarity pulse to intermittently supply a pause (0) pulse to a continuous positive (+) pulse train, and the size of the pulse train is a target. Characterized in that the pulse is controlled by the control unit to have a voltage (V) and 1/2 the target voltage (V) and is variably controlled to the size of V, 1 / 2V, 0, -V, -1 / 2V It is desirable to be a variable pulse grinding machine.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a power supply circuit of a variable pulse grinding apparatus according to the present invention, Figure 2 is a circuit diagram of a power supply DC output unit of the variable pulse grinding apparatus according to the present invention, Figure 3 according to the present invention Fig. 4 is a circuit diagram of a power supply DC pulse generator of a variable pulse grinding machine according to the present invention.

As shown in the drawings, the present invention relates to a grinding machine, a DC converter 10 and a DC / DC converter 30, DC pulse generator 40 and a control unit (DC / DC conversion of the unit power factor largely) 70) a variable pulse power supply.

The DC converter 10 shown in the drawing is a circuit unit for converting AC into DC.

Since the DC converter 10 is generally known and generally known, a detailed description thereof will be omitted.

The DC / DC converter 30 is a circuit unit that converts the output of the DC converter to DC / DC conversion of a unit power factor by a ZCS switching technique.

A specific example of the DC / DC converter 30 is illustrated in FIG. 2, and the driving mode of FIG. 2 will be described with reference to FIG. 3.

3 illustrates a driving mode of the DC / DC converter 10 when the gate amplifier driving signal is applied according to the control signal of the controller.

In general, when AC power is converted to DC power, switching control is performed, so that a large amount of loss occurs when switching ON and OFF.

Accordingly, the DC / DC converter 30 generates a DC power conversion unit by converting the switching power by ZVS (ZERO VOLTAGE SWITCHING) method with low conversion loss.

The power control of Figs. 2 and 3 is performed by SW1 and SW2, and the capacitors Csw1 and Csw2 are capacitors used for ZVS, and the controller uses the control chip UC3525.

The DC pulse generator 40 is a circuit unit for converting the unit power factor conversion output of the DC / DC converter 30 into a pulse train.

4 is a circuit diagram of the DC pulse generator 40 and shows a driving mode of the DC pulse generator 40.

According to FIG. 4, it can be seen that the outputs io and vo are changed by Qn switched by the control signal of the controller 70.

As shown in FIG. 4, the output is represented by V, 1 / 2V, 0, -V, -1 / 2V by the switching operation of the control unit 70.

In the present invention described above, one side electrode is supplied to the conductive grindstone side of the metal binder by a brush for feeding, and the other electrode is installed near one side of the peripheral surface of the grindstone, and the conductive grinding liquid is supplied between the grindstone and the other electrode. It is configured to be included in the grinding process for performing electrolytic dressing by applying power to the grindstone and the other electrode, so as to elute the electrode or dress the grindstone according to the switching control during the grinding process.

Hereinafter, the function of the grinding apparatus according to the present invention will be described.

As mentioned above, in the grinding process, in the case of the DC power supply system, unilateral and continuous electrolysis occurs in the grindstone, and the amount of the grindstone is significantly increased.

Therefore, in the prior art, there is an attempt to adjust the dissolution amount of the whetstone by supplying a direct current pulse wave power, in which case there is an advantage in that the amount of the whetstone is adjusted, but a significant amount of impurities are attached to the electrode as the whetstone is eluted. The problem still persists.

According to the power supply device of the present invention, it is possible to control the dissolution amount of the grindstone by supplying the pulse wave of V, and fine adjustment of the dissolution amount by adjusting the size to V or 1 / 2V as well as the period of the supplied pulse wave. This is possible.

On the other hand, impurities attached to the electrode can be removed by supplying a -voltage to elute the electrode.

Since the amount of impurities usually attached to the electrode is less than the dressing amount of the grindstone, the frequency of occurrence of the voltage is set by the controller so that the grindstone and the electrode are periodically dressed and eluted.

In addition, like the disadvantage of the DC power supply, continuous pulse wave input may cause an unbalanced dressing on the whetstone or electrode, and thus, the ideal dressing environment may be set by setting the idle power supply frequency to the controller.

Another function of the invention lies in the dressing of the electrode.

In the prior art, impurities attached to the electrode are inevitable.

However, according to the present invention, impurities attached to the electrode are removed.

Therefore, when the workpiece is a very small cylindrical inner surface, it is difficult to attach the electrode, the grinding process is impossible, but according to the present invention can be performed by using the workpiece as an electrode.

That is, according to the prior art method, when using the workpiece as an electrode can not avoid local discharge phenomenon of the workpiece, but according to the present invention can eliminate this phenomenon is suitable for ultra-precision mirror processing.

Therefore, there is an advantage that a defect-free mirror product can be obtained in a grinding operation using a workpiece as an electrode when grinding a very small cylindrical inner surface of a structure in which electrodes are hard to attach.

Summarizing the present invention described above, the grinding stone dressing form generally depends on the power supply type of the electrolytic power supply, the surface of the grinding wheel is eluted when the positive power is supplied, and the electrode is eluted when the negative power is supplied. The output of the electrolytic power supply periodically outputs a negative pulse train between positive pulse trains according to the setting of the controller, and the size of the pulse train is controlled and has an intermittent rest period. A grinding machine is provided that includes an adjustable power supply.

According to the present invention described above, there is provided an advantage of providing a variable pulse grinding apparatus including a power supply device which periodically outputs a negative pulse train between positive pulse trains according to the setting of the control unit, the size of the pulse train is controlled and has an intermittent pause. have.

In addition, there is an advantage that the variable pulse type grinding processing apparatus including a power supply that can adjust the dressing amount of the grindstone and the elution amount of the electrode according to the setting of the control environment to improve the quality of the grinding process.

And in the grinding using the workpiece as an electrode, there is an advantage that can remove the defects generated in the workpiece during processing.

Claims (2)

One side electrode is supplied to the conductive grindstone side of the metal binder by a brush for feeding, and the other electrode is installed near one side of the peripheral surface of the grindstone, and the conductive grinding liquid is supplied between the grindstone and the other electrode, and the grindstone and the other electrode In the grinding processing apparatus which applies an electric power and performs electrolytic dressing, A DC converter 10 for converting AC into DC; A direct current / direct current converter (30) for converting the output of the direct current converter into a unit power factor by a ZCS switching technique; A DC pulse generator 40 for converting the output of the unit power factor converter into a pulse train; A controller 70 for controlling the output size of the DC / DC converter and the pulse of the DC pulse generator according to a control signal of an external input device; Consist of, Variable pulse grinding machine including a power supply characterized in that the power supply is variable in size, width and polarity is output as a pulse train. The power supply of claim 1, wherein The idle pulse supply control and the reverse polarity pulse are supplied to the continuous positive polarity pulse train intermittently and the idle pulse is supplied intermittently. The magnitude of the pulse train is the target voltage (V) and one. Variable pulse type grinding processing, characterized in that the pulse is controlled by the control unit to have a / 2 target voltage (V) is variably controlled to the size of V, 1 / 2V, 0, -V, -1 / 2V Device.