US5149931A — Power source for electric discharge machining

Claim 1

Independent Claim 83 words

A power source for an electric discharge machining in which voltage is applied across an electrode and a workpiece to be machined to cause electric discharge in an interelectrode gap formed between said electrode and said workpiece to thereby machine said workpiece, comprising: an AC source for applying an AC voltage to an interelectrode gap having a capacitance; and a resonance circuit, for causing resonance to occur with the capacitance, whereby an electric discharge machining is carried out under an occurrence of resonance.

Claim 2

Dependent Claim 83 words

A power source for an electric discharge machining in which voltage is applied across an electrode and a workpiece to be machined to cause electric discharge in an interelectrode gap formed between said electrode and said workpiece to thereby machine said workpiece, comprising: an AC source for applying an AC voltage to an interelectrode gap having a capacitance; and a resonance circuit, for causing resonance to occur with the capacitance, whereby an electric discharge machining is carried out under an occurrence of resonance.

Claim 3

Dependent Claim 42 words

The power source as defined in claim 1 wherein said resonance circuit comprises capacitance means connected in parallel with said interelectrode gap and inductance means connected in series with said interelectrode gap, said resonance circuit being operatively connected to said interelectrode gap.

Claim 4

Dependent Claim 22 words

The power source as defined in claim 2 wherein said capacitance means is a capacitor and said inductance means is a coil.

Claim 5

Dependent Claim 42 words

The power source as defined in claim 1 wherein said resonance circuit comprises an inductance element existing in a circuit between said interelectrode gap and said AC source, said inductance element causing resonance to occur with the capacitance of said interelectrode gap.

Claim 6

Dependent Claim 46 words

The power source as defined in claim 1 wherein said resonance circuit comprises a coupling transformer provided near said interelectrode gap, resonance being caused to occur with the capacitance between an electrode and a workpiece, and the inductance of a secondary coil of said coupling transformer.

Claim 7

Dependent Claim 136 words

A power source for electric discharge machining in which voltage is applied across an electrode and a workpiece to be machined to cause electric discharge in an interelectrode gap formed between said electrode and said workpiece to thereby machine said workpiece comprising: an AC source for applying AC voltage to an interelectrode gap; an output detecting unit for detecting an output of said Ac source and for performing impedance matching with said interelectrode gap; and a frequency control circuit for automatically changing the frequency of said AC source according to a detection value provided by said output detecting unit, wherein a high frequency signal applied to said output detecting unit by said AC source is subjected to impedance-matching in response to variation in impedance of said interelectrode gap prior to being applied to said interelectrode gap.

Claim 8

Dependent Claim 136 words

A power source for electric discharge machining in which voltage is applied across an electrode and a workpiece to be machined to cause electric discharge in an interelectrode gap formed between said electrode and said workpiece to thereby machine said workpiece comprising: an AC source for applying AC voltage to an interelectrode gap; an output detecting unit for detecting an output of said Ac source and for performing impedance matching with said interelectrode gap; and a frequency control circuit for automatically changing the frequency of said AC source according to a detection value provided by said output detecting unit, wherein a high frequency signal applied to said output detecting unit by said AC source is subjected to impedance-matching in response to variation in impedance of said interelectrode gap prior to being applied to said interelectrode gap.

Claim 9

Dependent Claim 43 words

The power source as defined in claim 6 wherein the impedance-matching is effected by a T-type matching circuit including first and second coupling capacitors and a coil connected between a middle connection point of a series circuit of said capacitors and a ground.

Claim 10

Dependent Claim 93 words

A power source for electric discharge machining in which voltage is applied across an electrode and a workpiece to be machined to cause electric discharge in an interelectrode gap formed between said electrode and said workpiece thereby to machine said workpiece, comprising: an AC source for applying AC voltage to an interelectrode gap; and an automatic impedance-matching unit provided between said AC source and said interelectrode gap, wherein an electric discharge machining operation is carried out while impedance matching is automatically effected in response to variations in an impedance of said interelectrode gap.

Claim 11

Dependent Claim 93 words

A power source for electric discharge machining in which voltage is applied across an electrode and a workpiece to be machined to cause electric discharge in an interelectrode gap formed between said electrode and said workpiece thereby to machine said workpiece, comprising: an AC source for applying AC voltage to an interelectrode gap; and an automatic impedance-matching unit provided between said AC source and said interelectrode gap, wherein an electric discharge machining operation is carried out while impedance matching is automatically effected in response to variations in an impedance of said interelectrode gap.

Claim 12

Dependent Claim 83 words

The power source as defined in claim 8 wherein said automatic impedance-matching unit comprises: a T-type matching circuit including first and second coupling capacitors and a coil connected between a middle point of a series circuit of said first and second capacitors and a ground; and an actuating means for varying the capacitance of said second capacitor so as to minimize a ratio of a reflected wave to a travelling wave according to the signal levels of the preceding reflected and travelling waves.

Claim 13

Independent Claim 73 words

An apparatus for use in electric discharge machining by providing a voltage across an interelectrode gap formed between an electrode and a workpiece to be machined, the interelectrode gap having a capacitance, said apparatus having a stray capacitance, said apparatus comprising: power source means for producing an AC voltage; and resonance setting means for substantially eliminating a stray capacitance and for placing said apparatus in resonance with the capacitance of an interelectrode gap.

Claim 14

Independent Claim 73 words

An apparatus for use in electric discharge machining by providing a voltage across an interelectrode gap formed between an electrode and a workpiece to be machined, the interelectrode gap having a capacitance, said apparatus having a stray capacitance, said apparatus comprising: power source means for producing an AC voltage; and resonance setting means for substantially eliminating a stray capacitance and for placing said apparatus in resonance with the capacitance of an interelectrode gap.

Claim 15

Dependent Claim 50 words

An apparatus as defined in claim 10, wherein the AC voltage has a frequency, and wherein said resonance setting means comprises a frequency control circuit for changing the frequency of the AC voltage in response to a change in impedance of said interelectrode gap to maintain said apparatus in resonance.

Claim 16

Independent Claim 128 words

An apparatus for use in electric discharge machining by providing a voltage across an interelectrode gap formed between an electrode and a workpiece to be machined, the interelectrode gap having a capacitance, said apparatus comprising: power source means for producing an Ac voltage having a frequency; output detection means for detecting a travelling wave signal level and a reflected wave signal level; impedance matching means for use in matching impedance of said apparatus with a capacitance of an interelectrode gap; and frequency control means for changing the frequency of the AC voltage in response to a change in impedance of said interelectrode gap to maintain said apparatus in resonance based on the travelling wave signal level and the reflected wave signal level detected by said output detection means.

Claim 17

Independent Claim 128 words

An apparatus for use in electric discharge machining by providing a voltage across an interelectrode gap formed between an electrode and a workpiece to be machined, the interelectrode gap having a capacitance, said apparatus comprising: power source means for producing an Ac voltage having a frequency; output detection means for detecting a travelling wave signal level and a reflected wave signal level; impedance matching means for use in matching impedance of said apparatus with a capacitance of an interelectrode gap; and frequency control means for changing the frequency of the AC voltage in response to a change in impedance of said interelectrode gap to maintain said apparatus in resonance based on the travelling wave signal level and the reflected wave signal level detected by said output detection means.

Claim 18

Dependent Claim 27 words

An apparatus as defined in claim 12, wherein said apparatus has a stray capacitance associated therewith, and wherein said impedance matching means substantially eliminates the stray capacitance.

Claim 19

Independent Claim 63 words

An apparatus for use in electric discharge machining by providing a voltage across an interelectrode gap formed between an electrode and a workpiece to be machined, the interelectrode gap having a capacitance, said apparatus comprising: power source means for producing an AC voltage; and impedance matching means for automatically maintaining a matched impedance of said apparatus with a capacitance of an interelectrode gap.

Claim 20

Independent Claim 63 words

An apparatus for use in electric discharge machining by providing a voltage across an interelectrode gap formed between an electrode and a workpiece to be machined, the interelectrode gap having a capacitance, said apparatus comprising: power source means for producing an AC voltage; and impedance matching means for automatically maintaining a matched impedance of said apparatus with a capacitance of an interelectrode gap.

Claim 21

Dependent Claim 67 words

An apparatus as defined in claim 14, wherein said impedance matching means comprises: output detection means for detecting a travelling wave signal level and a reflected wave signal level; and control means for maintaining the matched impedance in response to a change in impedance of said interelectrode gap based on the travelling wave signal level and the reflected wave signal level detected by said output detection means.

Claim 22

Dependent Claim 29 words

An apparatus as defined in claim 15, wherein said impedance matching means further comprises a variable capacitor, and wherein said control means comprises means for adjusting said variable capacitor.

Claim 23

Dependent Claim 27 words

An apparatus as defined in claim 14, wherein said apparatus has a stray capacitance associated therewith, and wherein said impedance matching means substantially eliminates the stray capacitance.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1995-09-22	1996-03-23	1996-09-22	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1999-09-22	2000-03-23	2000-09-22	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2003-09-22	2004-03-23	2004-09-22	$7700.00	Window Closed / Lapsed

Power source for electric discharge machining

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