JPS6320659B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention uses a conductive grindstone to precisely and efficiently cut workpieces made of all kinds of materials through the actions of electrolysis, electrical discharge, and grinding. The present invention relates to a processing method for performing grinding processing and a processing device for carrying out the method.

(Prior Art) Conventionally, electrical discharge machining, which uses electrical energy, has been employed for grinding and precision cutting of difficult-to-process materials such as cemented carbide.

However, since this electrical discharge machining method is based on electrical conductivity, it has the disadvantage that it cannot be applied to machining non-conductive and difficult-to-process materials such as ceramics, glass, quartz, crystal, and sapphire. .

In order to eliminate this drawback, the present inventors previously developed a disc-shaped grindstone 1 in which non-conductive polishing parts 2 and conductive parts 3 are arranged radially and alternately, as shown in FIG. A conductive ring 4 is provided to connect with the conductive part 3, a power source 6 is connected between the conductive ring 4 and the workpiece 5, and a special machining liquid is applied between the rotating grindstone 1 and the workpiece. The authors proposed a so-called "electrolytic discharge grinding method" in which conductive and non-conductive workpieces 5 are machined by applying alternating current or direct current voltage.

In this electrolytic discharge grinding method, the grinding wheel 1 rotates,
When the conductive part 3 comes close to the workpiece 5, electrolysis and discharge occur due to the presence of machining fluid, and the part that has become extremely brittle due to the discharge energy is ground using the abrasive part 2. It is thought that there is.

(Problems to be Solved by the Invention) However, this electrolytic discharge grinding method can perform the processing only when using a grindstone 1 in which abrasive portions 2 and conductive portions 3 are alternately formed. However, it has the disadvantage that it cannot be processed with other grindstones, that is, not only with non-conductive grindstones but also with completely conductive grindstones.

The present invention has been made in consideration of the above drawbacks, and its purpose is to control an alternating waveform every half wave between a grinding wheel and a workpiece that comes into contact with the grinding wheel.
To provide an electrolytic discharge grinding method and device that can perform the above-mentioned grinding process using any grindstone as long as the grindstone has conductivity by applying an output voltage or current having a waveform most suitable for the process. It is in.

(Means and effects for solving the problems) Therefore, the present invention first provides an electrolytic discharge grinding method in which an alternating conductive grinding wheel is installed between a rotating disc-shaped conductive grinding wheel and a workpiece that comes into contact with the grinding wheel. The basic waveform is a basic waveform, and a pulse wave is superimposed on it to apply an output voltage or current controlled to a waveform suitable for processing every half wave.Secondly, the first support as the processing equipment is a workpiece supported by the mechanism; and a second support mechanism movable relative to the first support mechanism.
a disc-shaped conductive grindstone supported by a support mechanism;
a drive mechanism that is connected to the first or second support mechanism and drives the first or second support mechanism relative to the other; the conductive grindstone; and a workpiece that contacts the conductive grindstone. Its configuration is to provide a power source between the product and the object, which applies an output voltage or current controlled to a waveform suitable for processing every half wave by using an alternating waveform as a basic waveform and superimposing a pulse wave on it.
These configurations are intended to solve the above problems.

Hereinafter, the structure and operation of the present invention will be explained in more detail.

Figure 1 shows a block diagram for explaining the electrolytic discharge grinding method and apparatus of the present invention.
is an AC power supply, 7 is a power supply circuit, 8 is a signal generation circuit,
9 is a waveform shaping circuit, 10 is an output circuit, and 11 is a switching circuit, and the output terminal of the switching circuit 11 is used to apply an electric current between the first support mechanism 12 that supports the workpiece 13 and the disc-shaped conductive grindstone 14. has been done.

Further, the disc-shaped conductive grindstone 14 is supported by a second support mechanism 15 , and the second support mechanism 15 is driven by a drive mechanism 16 relative to the first support mechanism 12 .

The conductive whetstone 14 mentioned here is generally made by mixing abrasive grains with metal powder, mixing glass or resin as a binder, and sintering this into a disk shape, or by mixing a binder with abrasive grains. A general disc-shaped grindstone sintered with electroless plating to give it conductivity, or a metal disc with diamond particles or CBN particles alloyed around the periphery (mainly copper alloy)
There are products that are baked or electrodeposited as a binder.

In addition, as shown in FIG.
If the disc-shaped grinding wheel 14 is thin as shown in FIG. Grooves 18 alternately on both the front and back sides.
In some cases, a metal is inserted into the groove 18, a metal is bonded to the inner surface, or a conductive paint is applied.

Furthermore, as shown in FIG. 2C, there is also one in which a hole 19 is penetrated from the end of the disc-shaped grindstone 14 to the center, and a metal is inserted into this hole 19. In addition, as shown in FIG.
A metal layer or a conductive paint layer may be provided on the inner surface of the 0.

In the present invention configured in this manner, the power source 6 is a commercial frequency power source or an AC power source close to this commercial frequency, and the AC voltage from the power source 6 is either full-wave rectified in the power source circuit 7 or the waveform is changed as it is to the peak value. Different voltages are input to the switching circuit 11. Also,
The signal generating circuit 8 generates a pulse signal using a thyristor (SCR) or a silicon symmetrical switch (SSS), and inputs it to the switching circuit 11. The waveform shaping circuit 9 shapes the voltage from the power supply circuit 7 into a square wave signal and outputs the square wave signal. Control circuit 1
0 is composed of a transistor, a thyristor, etc., and controls the output of the transistor or thyristor by the output from the power supply circuit 7, signal generation circuit 8, and waveform shaping circuit 9, and controls the current flowing to the grindstone 14 and the workpiece 13. A switching circuit 11 generates a voltage by combining outputs controlled every half wave from a power supply circuit 7, a signal generation circuit 8, and a waveform shaping circuit 9, and superimposing pulses suitable for the structure of a workpiece 13 and a conductive grindstone 14. is applied between the conductive grindstone 14 and the workpiece.

When using a normal power source that does not have the ability to generate pulses, processing can only be done with a grindstone that has alternating conductive parts and abrasive parts as described above. Electric discharge occurs only occasionally, and therefore machining at this time is performed mainly by mechanical grinding action and electrolytic action, and the ratio of the electric discharge action is small.
For this reason, high efficiency machining could not be expected.

However, according to the present invention, a power supply with a pulse generation function added to an alternating box power supply is used, and the frequency can be changed freely, so even if a completely conductive grinding wheel is used, the output waveform will not change. By forming the pulse into an appropriate waveform, it is possible to generate frequent electrical discharges corresponding to the frequency of the pulses in the contact area of the grinding wheel and the workpiece, and the workpiece is constantly exposed to three types of mechanical grinding, electrolysis, and electrical discharge. The action becomes effective.

As a result, compared to the conventional machining method that uses a power source that does not have pulse generation capability and cannot control the waveform itself in a complex manner, the present invention enables significantly more efficient machining using a fully conductive grindstone. At the same time, the generation of burrs on the edge of the workpiece surface is suppressed by the discharge spark, making it possible to perform precise machining.

In addition, in the processing method of the present invention, the waveform is controlled every half wave based on an alternating waveform, so for example, one half wave is a waveform suitable for processing the workpiece, and the remaining half wave is used to dress the grindstone. It is also possible to create a suitable waveform, and it becomes possible to process the workpiece and dress the grindstone at the same time, with the most suitable output for each. On the other hand, with conventional machining methods that cannot control the waveform for each half wave, the optimal waveform for processing the workpiece and the optimal waveform for dressing the grinding wheel generally do not match, but the optimal waveforms are formed for each. Because processing is performed without being able to do it,
In this respect as well, highly efficient machining cannot be expected. That is,
According to the present invention, the sharpness of the whetstone continues for a long time, and effective cutting and grinding processing can be performed without leaving any distortion or defects on the workpiece.

Furthermore, in the case of full-wave rectification in the present invention so that only the side of the workpiece is positive, it becomes possible to independently and alternately apply different processing effects to the workpiece for every half wavelength. This is based on the knowledge that compared to conventional machining methods that do not control each half-wave, the present invention, which utilizes the effects of each half-wave synergistically and effectively, can achieve much higher machining efficiency. It is based on In other words, in conventional machining methods that do not allow waveform control for each half-wave, it is not possible to separate the electrolytic action and the electrical discharge action, so both actions always act on the workpiece at the same time, resulting in each action being incomplete. Once the machine gets used to it, it is no longer possible to expect the workpiece to be processed more efficiently. On the other hand, in the present invention, both effects are completely separated every half wavelength by wiring and adjustment of the power supply, and each effect is made independent as the optimum waveform for that effect, and each effect of electrolysis and discharge is made to work alternately. As a result, both effects act synergistically on the workpiece, greatly improving machining efficiency.

(Example) Hereinafter, an example of the present invention will be described in more detail based on the drawings.

FIG. 3 is a diagram showing a part of a specific embodiment of the circuit shown in FIG. 1. In the power supply circuit 7, the circuit to which the transformer PT ₁ is connected is the main power supply circuit for outputting the processing power; The primary winding of this transformer PT ₁ is connected to the power supply 6, and the secondary winding is connected to the rotary switch.
Terminals A and B are connected via RS and a rectifier circuit REC ₁ , and when connected to terminals A' and B', the rectifier circuit REC ₁ is disconnected. The circuit to which the transformer PT ₂ is connected is a power supply circuit that provides input to the pulse generation circuit 8, the primary winding is connected to the power supply, and one end of the secondary winding is connected to the rectifier circuit REC ₂ and a terminal via the resistor R ₁ . C, the other end is connected to terminal D via the rectifier circuit REC ₂ , and a capacitor is connected between terminals CD.
C ₁ and Zener diode Z ₁ are connected. The circuit to which the transformer PT ₃ is connected is a power supply circuit for providing a smooth or sinusoidal full-wave bias current to the output circuit 10, and one end of the primary winding is connected to a rectifier circuit REC ₃ .
It is connected to a terminal E via a resistor _R2 , the other end is connected to a terminal F via a rectifier circuit _REC3 , and a capacitor _C2 and a Zener diode _Z2 are connected between the terminals EF.

The signal generation circuit 8 is a circuit that generates a pulse to be superimposed on the output, and the terminal G is connected to the terminal K.
Terminal H is a variable resistor via variable resistor VR ₁ , silicon symmetrical switch SS, and variable resistor VR ₂ .
VR ₃ is connected to one end, the other end is connected to terminal K, the slider is connected to terminal J, and capacitor C ₃
One end is connected to the connection point of variable resistor VR ₁ and silicon symmetrical switch SS, and the other end is connected to terminal G.
It is connected to the.

The waveform shaping circuit 9 is a circuit that converts the output of the output circuit 10 into a square wave, and the terminals L and M are rectifier circuits REC ₄
The terminal N is connected to the terminal S, the terminal Q is connected to the terminal R via the coil CH, one end of the capacitor _C4 is connected to the terminal R, and the other end is connected to the terminal R. Connected to S.

The output circuit 10 includes a conductive grindstone 14 and a workpiece 1
This circuit controls the voltage applied between terminals 3 and the current flowing through them, and variable resistors VR ₄ and VR ₅ are connected between terminals T and U, and the slider of variable resistor VR ₄ is connected to variable resistor VR _6. and the base of the transistor TR via the diode _D1 , the terminal V is connected to one end of the diode DI and the collector of the transistor TR, and the emitter is connected to the terminal W via the resistor _R3 .
and the other end of the diac DI is connected to terminal W.
It is connected to the. Furthermore, terminal X is a diode D ₂
is connected to the base of transistor TR through.

Note that the terminals X and Y are connected to the conductive grindstone 14 and the workpiece 13.

In the circuit of this embodiment configured in this way,
Terminal A becomes terminal Z, terminal B becomes terminal M, terminal Z becomes terminal L, terminal C becomes terminal G, terminal D becomes terminal H
When terminal N is connected to terminal V, terminal S to terminal W, terminal E to terminal U, terminal F to terminal T, terminal J to terminal X, and terminal K to terminal W,
As shown in FIG. 4A, a waveform in which pulses are superimposed on a full-wave rectified waveform is output. The width of this pulse, that is, the number of pulses superimposed on a half wave, can be arbitrarily set to one or more by varying the variable resistor _VR1 .

Furthermore, in the above connection, if the terminals A' and B' are connected instead of terminals A and B, the waveform will be such that pulses are superimposed on the alternating current from the power source 6, as shown in FIG. 4B.

Furthermore, terminal A' becomes terminal P, terminal B' becomes terminal Q,
By connecting terminal R to terminal Z, a waveform in which a sine wave is converted into a square wave and pulses are superimposed as shown in FIG. 4C can be obtained. Also rotary switch RS
The average voltage can be made variable by changing the voltage.

By controlling the output voltage every half wave as described above, a voltage with a waveform in which pulses are superimposed is applied between the conductive grindstone 14 and the workpiece 13,
Therefore, the superimposed pulses cause continuous micro-discharge, and the abrasive grain portion grinds and dresses the workpiece.

FIG. 5 shows a partial configuration diagram of another specific embodiment of the present invention, in which elements with the same symbols as in FIG. 3 indicate the same elements, and the power supply circuit 7 of this embodiment In this case, the rectifier REC ₁ is omitted from the terminals A and B, and the terminal E ₁ is connected to the rectifier REC ₃ via the resistor R ₁ , the terminals E ₂ and E ₃ are connected, and the terminals E ₂ , E ₃ and the terminal capacitor C between ₂ and zener diode
Connecting ZD ₂ .

The signal generation circuit 8 includes a silicon symmetrical switch SS, variable resistors VR ₁ and VR ₂ , and a capacitor C _3.
Silicon symmetrical switch in parallel to the circuit of
SS', variable resistors VR' ₁ , VR' ₂ and capacitor C' ₃ are connected, and respective sliders of variable resistors VR ₂ and VR' ₂ are connected to terminals J ₁ and J ₂ .

The output circuit 10 is a transistor TR and a diode.
Transistor TR _{' , diode D'1 , D' 2 ,}
D′ ₃ , resistor R′ ₃ and variable resistor VR′ ₄ circuit are connected.

In the circuit of this embodiment configured in this way, the alternating waveform, which is the fundamental wave, can be controlled from the power supply 6 as separate waveforms for each half cycle, so that the output of each independent waveform can be controlled. I can put it out. Therefore, when an alternating current is applied between the conductive grinding wheel 14 and the workpiece 13, for example, a half cycle of the waveform is outputted as a waveform suitable for grinding the workpiece, and the other half cycle is outputted as a waveform suitable for grinding the workpiece. It is possible to output a voltage with a waveform suitable for refinishing a grindstone.

The connection relationship of each terminal and the voltage waveforms applied to the conductive grindstone 14 and the workpiece 13 to obtain such waveforms will be explained with reference to FIGS. 5 to 10.

() First connection First, terminal A is connected to terminal Y, terminal B is connected to terminal _V1 ,
Terminal C to terminal G, terminal D to terminal H, terminal E ₁
Connect terminal E ₂ to terminal E 2, terminal E ₃ to terminal T, terminal F to terminal U, terminals J ₁ and J ₂ to terminals X ₁ and X ₂ , respectively, connect terminal Z to terminal V ₂ , and connect the power supply. By selecting an arbitrary voltage with the rotary switch RS of the circuit 7 and selecting the pulse generation interval and pulse height to be superimposed with the variable resistors VR ₁ and VR' ₁ of the signal generator 8, the sixth
The waveforms shown in Figures A, B, C, D, and Ho can be obtained.

() Second connection Also, in the above, terminals E ₁ and E ₂ are not connected,
By opening terminals E ₂ and E ₃ and connecting terminal T to terminal E ₁ , the waveforms shown in FIG. 7 A and B can be obtained.

As is clear from the figure, the output waveform formed by the first and second connections is one in which alternating deformation is deformed or a pulse wave is superimposed every half wave of the alternating deformation. We are trying to process and dress the grindstone every half wave.

() Third connection Also, in the first connection, terminal A of the power supply circuit 7
to terminal M, terminal B to terminal V ₁ , terminal L to terminal
By connecting the terminal N to the terminal _Y and the terminal P to the terminal Z, the terminals A, B, C, D, Ho,
It is possible to obtain the following waveform.

() Fourth connection In the third connection, terminals E ₁ and E ₂ are not connected,
If terminal E ₂ and terminal E ₃ are opened and terminal E ₁ is connected to terminal T, the waveforms shown in FIG. 9 A and B can be obtained.

() Fifth connection In the third connection, terminal B is connected to terminal L, and terminal S
When connected to terminal V ₁ , terminal N to terminal Q, and terminal R to terminal Y, a voltage with the waveform shown in FIG. Can be done.

As described above, the output waveforms obtained by the third to fifth connections are examples of full-wave rectification, and the waveforms are controlled every half wave depending on the type of workpiece, the type of grinding wheel, etc., and the machining action, that is, the discharge Both effects of electrolysis are made to work independently and optimally for each half wave.

This will be explained by giving a more specific example.

Currently, I have a metal bond diamond grindstone with a diameter of 100 mm and a thickness of 5 mm (grain size 170 mesh, concentration level 100).
Using the same motor load current (3.1A)
The diamond sintered body was ground by changing the voltage waveform.

Voltage waveform: (a) Fully rectified waveform without superimposing a pulse wave (b) Fully rectified waveform with the same pulse wave superimposed (c) Fully rectified waveform with a pulse wave superimposed on a half wave and the next half wave left as is Machining conditions: Grinding wheel rotation speed 5000 (rpm) Grinding wheel relative movement speed 10 (mm/min) Looking at the results, the cutting depth is 15 μm in waveform (a),
It was found that the cutting depth in waveform (c) reached 60 μm, whereas it was 25 μm in waveform (b), and the grinding efficiency was significantly improved.

Note that the switching circuit 11 may connect the above-mentioned terminals mechanically, but the output of each waveform can be programmed using a microcomputer. Further, the waveforms shown in FIGS. 6 to 10 can be arbitrarily selected depending on the type of conductive grindstone 14 and the type of workpiece.

(Effects of the Invention) As described above in detail, according to the present invention, a pulse is superimposed on the conductive grindstone and the workpiece based on an alternating waveform every half wave, or the waveform is changed to generate a voltage. Or, since a current is applied, it is possible to process all types of workpieces using not only conventional conductive grindstones with a specific structure but also all types of conductive grindstones. The smoothed voltage output, the height of the superimposed pulses, the pulse interval, the number of pulses, etc. can be freely set for each half wave.
Optimal processing conditions can be set for all workpieces, allowing efficient and precise processing.

Here, the pulse wave mainly contributes to the discharge action, and the smooth wave contributes to the electrolysis action, but in the present invention, the action is not limited to the workpiece, and for example, alternating voltage or current may be used. By controlling each half wave to the appropriate waveform without inversion,
Of course, it not only performs the three actions of electrolysis, electrical discharge, and grinding on the workpiece, but also performs a dressing action on the grindstone at the same time, which prevents clogging of the grindstone over a long period of time and maintains its sharpness for a long time. It can be sustained.

Furthermore, in the present invention, for example, when a part of the alternating waveform is inverted and full-wave rectification is performed, and waveforms suitable for electric discharge and electrolysis are formed independently for each half wave, electric discharge is applied to the workpiece. The action and the electrolytic action work independently and sequentially, and the machining efficiency is further improved compared to the half-finished action that occurs when waveform control is not possible as in the past.

Further, in the present invention, since the voltage and current can be selected to the optimum values for each half wave as described above, the average current can be reduced and power consumption can also be reduced.

[Brief explanation of the drawing]

Figure 1 is a block diagram of an embodiment of the present invention, Figure 2 is a partial three-dimensional diagram of an example of a conductive grindstone, Figure 3 is a circuit diagram showing a specific embodiment of the block diagram of Figure 1, and Figure 4. is a waveform diagram obtained by the circuit of FIG. 3, FIG. 5 is a circuit diagram showing another specific example of the block diagram of FIG. 1, and FIGS. 6 to 10 are diagrams of the circuit of FIG. 5. Output waveform diagrams in various connection states of each terminal, 1st
FIG. 1 is a schematic three-dimensional diagram for explaining a conventional electrolytic discharge grinding method. Explanation of main parts of the diagram, 6...Power supply, 7...Power supply circuit, 8...Signal generation circuit, 9...Waveform shaping circuit, 10
...output circuit, 11...switching circuit, 12...support mechanism, 13...workpiece, 14...conductive grindstone, 1
5... Support mechanism, 16... Drive mechanism.

Claims (1)

[Scope of Claims] 1. An alternating waveform is used as a basic waveform between a rotating disc-shaped conductive grindstone and a workpiece in contact with the grindstone, and a pulse wave is superimposed on this waveform for processing every half wave. An electrolytic discharge grinding method characterized by applying an output voltage or current controlled to a waveform suitable for. 2. The electrolytic discharge grinding method according to claim 1, wherein the average value of the output voltage or current is positive on the workpiece side. 3. A workpiece supported by a first support mechanism, a disc-shaped conductive grindstone supported by a second support mechanism movable relative to the first support mechanism, and the first or a drive mechanism that is connected to a second support mechanism and drives the first or second support mechanism relative to the other; and the conductive grindstone and the workpiece that contacts the conductive grindstone. An electrolytic discharge grinding machine characterized in that it is provided with a power source that applies an output voltage or current controlled to a waveform suitable for machining every half wave by superimposing a pulse wave on the basic waveform of an alternating waveform. 4. The electrolytic discharge grinding apparatus according to claim 3, wherein the average value of the output voltage or current is positive on the workpiece side. 5. The electrolytic discharge grinding apparatus according to claim 3, wherein the power source has a waveform changing means that can change the waveform continuously and steplessly.