JPS5828523B2 - kangekisokuteisouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for easily and accurately measuring the length of a gap between two objects, particularly a minute gap such as a machining gap in electrical discharge machining or electrolytic machining.

Conventionally, methods proposed for measuring the gap length involve actually moving one of the objects (electrodes) forming the gap until they touch each other, and then generating a pulse corresponding to the amount of movement using an appropriate pulse converter. There is a method of determining the gap length by counting the generated pulses, but with this method, it is not possible to measure the gap while keeping it constant, and the error is removed when converting the travel distance into pulses. arise,
Since this is counted and integrated, it is an unavoidable drawback that a considerable amount of error occurs, although it depends on the precision of the pulse conversion device.

In view of this point, the present invention is designed to enable measurement with high precision while maintaining the gap to be measured as it is.

That is, as shown in Fig. 1, a gap G with opposing electrodes is provided in a certain medium, and a capacitor C charged at the power supply voltage ■ is connected between the opposing electrodes via a switch S to form a discharge circuit. .

Therefore, if we observe the transient phenomenon when the switch S is closed and a pulse voltage is applied to the gap G by the capacitor C charged to voltage ■ to generate a discharge, we will see that even if the switch S is closed, the discharge does not start immediately. At first, a weak current flows, and only when it reaches a current value with a critical current density does a spark discharge occur.

This situation is shown in FIG. 2. A weak current IL flows from the closing point 0 of the switch S, and a large current i that generates a spark discharge flows only after a time τ.

The following equation has been proposed based on various experimental results focusing on this discharge precursor phenomenon.

Therefore, this equation (1) becomes as follows.

C: Constant, that is, according to this equation (2), when generating a discharge in the gap G, if the electric type conductivity K of the gap medium and the test pulse voltage ■ to generate the discharge are known, the delay time τ of the discharge can be calculated. By measuring, the gap length l can be easily determined.

The present invention is an application of this, and will be explained below with reference to drawings of embodiments.

In FIG. 3, 1 is a rotating electrode, 2 is its rotating motor,
Reference numeral 3 denotes a workpiece attached to a processing table that is fed by NC, and faces the electrode 1 to form an electrical discharge machining gap.

4 is a machining tank, 5 and 6 are pulse motors for NC machining feed, 7 is an NC control device, 8 is a nozzle for supplying machining fluid into the machining gap, 9 is its pump device, and 10 is an electrical conductivity of the supplied machining fluid. The ion exchange resin is controlled; 11 is a resistance measuring device for measuring the electrical conductivity of the supplied machining fluid; and 12 is a power supply device for applying a test pulse voltage to the machining gap and applying a machining drop pressure.

13 is a gap applied voltage measurement device, 14 is a discharge delay time measurement device, 15 is an arithmetic device that calculates the gap length from each of these measured values, 16 is a measurement gap length display, and 17 is a correction signal controlled by NC. This is a correction device that performs predetermined gap control in addition to device 7.

In the above, the electrical conductivity of the supplied machining fluid can be changed and controlled by the ion exchange resin 10, and the test pulse voltage applied to the gap can also be changed arbitrarily by the power source 12.

Now, the pulse motor 5.6 is driven and controlled by the NC device 7 to feed the workpiece 3, and the gap between it and the rotating electrode 1 is determined.

A machining fluid (water) is supplied in a jet stream to the gap by the operation of the pump 9, and the electrical conductivity of this supplied fluid is sequentially detected and measured by a resistance measuring device 11.

Therefore, a test pulse voltage is applied from the power source 12 to the gap to which the liquid of constant electrical conductivity is supplied.

The applied voltage V is accurately measured by a measuring device 13, and the measurement results of these measuring devices 11 and 13 are supplied to an arithmetic device 15.

On the other hand, the delay time τ from the voltage application to the occurrence of discharge is detected and measured by the measuring device 14, and this measured value is also added to the arithmetic device 15, and based on these measurement results, the arithmetic device 15 calculates the above-mentioned relational expression. The calculation of (2) is performed to calculate and determine the measurement gap length between the electrode 1 and the workpiece 3, and it is displayed at 16.

Next, for example, the ion exchange resin 1 of the liquid supplied from the pump 9
The measurement using each device is repeated while changing the degree of ion exchange treatment by 0, and the gap length is adjusted each time by the device 15,
16 is calculated and displayed.

In addition, the gap length may be measured and calculated multiple times while changing the voltage applied to the gap from the power supply 12, and by taking the average value of the measurements by changing the discharge conditions, for example. It is possible to measure gap length with extremely high accuracy.

If the result is different from the expected gap, the device 17 applies a correction signal corresponding to the difference to the NC device 7 for control, thereby making it possible to set an accurate gap.

While rotating the electrode 1 while maintaining the gap set in this way, and while rotating the electrode 5 times while maintaining a constant gap, machining voltage pulses are applied from the power source to achieve the high precision planned by electrical discharge machining. can be processed.

Of course, the same applies to electrolytic machining, but in this type of electrical machining, the setting of the gap is a decisive factor in machining accuracy, and by measuring this as described above and setting it to a high degree of accuracy, extremely high accuracy can be achieved. can be made possible.

By providing a gap measurement and setting cycle during the machining process, all machining operations can be completed with high precision.

In the example circuit, the voltage measuring device 13 is connected to the power source 12.
It is not necessary to provide it separately by storing it in a separate space.

Further, the calculation device 15 may be a calculation table or the like that does not have a calculation function.

The present invention has been described above with reference to one embodiment. However, the medium to be supplied to the gap for gap length measurement is not limited to liquid, but also gas. ＼It can be measured without contact, and the gap length can be measured with high accuracy over a wide range from a few microns to as large as a few microns by selecting the electrical conductivity of the fluid as the supply medium and the applied voltage for discharge. can.

That is, since the electrical conductivity of the supplied fluid and the applied voltage for testing can be changed arbitrarily, the gap length can be easily measured by setting and controlling the values according to the width or narrowness of the measurement gap.

Note that the gap to be measured is not limited to the electrical machining gap in the above embodiment.
It can be conveniently used for measuring various slit gaps and other gaps.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram explaining the present invention in detail, FIG. 2 is a diagram explaining a part of the operating state, and FIG. 3 is a diagram showing the configuration of an apparatus according to an embodiment of the present invention.

Claims (1)

[Claims] 1 A device for supplying a discharge medium fluid to the gap to be measured, a device for applying a test pulse voltage to generate a discharge, a device for measuring the electrical conductivity of the supplied fluid, and a device for applying a test pulse voltage to the gap. A device that measures the delay time from when the discharge occurs until discharge occurs, and furthermore, the electrical conductivity of the fluid supplied from each of the devices, the discharge delay time τ, and the test pulse voltage■
Input the signal and use the formula τ=Cx-"xV" (C is a constant)
1. A gap measuring device comprising: a calculation device for calculating l.