Device for electtolytic grinder

Claim 1

A feed rate control device for an electrolytic grinder comprising a spark detector circuit for detecting a spark generated between a grinding electrode and a work piece and producing a pulse signal in response to the generation of said spark, a reducing circuit for producing the number of pulses equal to the difference between the number of all pulses included in said pulse signal produced from said spark detector circuit and the number of pulses produced by said spark detector circuit for a predetermined period of time, an ignorance time setting circuit for presetting a time period during which the working area and/or the amount of working current is smaller than a predetermined value or during which the work piece tends to generate a spark, an accelerator circuit for producing an acceleration pulse signal only when no signal is produced by said reducing circuit even after a predetermined period of time, a circuit for sharply reducing the feed rate of the worktable to a relatively low level in response to the first spark detected by said spark detector circuit in the case where a work piece of such material as a very hard alloy or silver-tungsten alloy requires a very low feed rate compared with the maximum feed rate, a memory circuit for memorizing the feed rate of the worktable in accordance with the acceleration pulse signal from said accelerator circuit and the pulse signal from said reducing circuit, a read circuit for reading the content stored in said memory circuit, a circuit for converting a signal from said read circuit into a DC voltage and a drive motor which rotates at a rate proportional to the magnitude of the DC voltage sent from said converter circuit.