DE1030945B - Switching arrangement for spark erosion with alternating current or direct current - Google Patents

Description

The invention relates to a circuit arrangement for spark erosion with alternating current or Direct current.

In known devices of this type, the circuit contains the alternating current or direct current can lead, generally a capacitor, one of whose terminals one (with direct current the negative polarized) is connected to the electrode (tool) and the other to the workpiece, and between A spark gap is maintained between the electrode and the workpiece.

This known arrangement has the disadvantage that during the discharge of the capacitor on the Spark gap Current flows into the discharge circuit and thus an arc is formed from the power source over the spark gap can cause what the cutting or other erosion process strong impaired. It is therefore the aim of the invention to design the circuit so that the spark gap does not receive a significant amount of current from the power source directly and that the current in the charging circuit only serves to charge the capacitor (or capacitors), which then alone is a spark discharge generated between the workpiece and the electrode.

The invention consists in having two or more capacitors in series with the power source continuously are connected such that during a capacitor discharge period from the charging circuit in the discharge circuit no current can flow to the extent that the spark discharge in a Arc could pass.

In an advantageous embodiment of the invention, two of them are in series with the power source lying capacitors one connected as a charge carrier parallel to the spark gap. But it can switches are also provided in such a way that the capacitors one after the other in a manner known per se and discharged cyclically via the spark gap.

In a further development of the invention, a plurality of capacitors can be connected to the circuit of the The electrode and the workpiece are connected in such a way that a capacitor is always charged, while the other or the others are being discharged, or there can always be two capacitors one after the other charged and discharged together via the spark gap. With such arrangements can higher spark frequencies through the use of rotating switches or gas discharge paths etc. and thus corresponding improvements in the labor yield and accuracy can be achieved.

The drawing shows a simplified representation of some exemplary embodiments of the object of the invention Country.

Circuit arrangement for spark erosion
with alternating current or direct current

Applicant:
Sparcatron Limited, Bath (Great Britain)

ίο Representative: Dipl.-Ing. A. Droth, patent attorney,

Kassel, Kurt-Schumacher-Str. 11

Claimed priority:
Great Britain October 27, 1953

Gregory Fefer, Newnham-on-Severn,
and Dagobert William Rudorff, London

(Great Britain),
have been named as inventors

The workpiece is denoted by 1 and the electrode serving as a tool is denoted by 2. 3 and 4 are the Lines drawn from a suitable power source, e.g. B. an AC power source. 5 is a series switched capacitor between the supply line 4 and the connecting line 6 to the electrode 2. On Shunt capacitor 7 lies between the supply line 3 and the connecting line 6 in parallel the spark gap between the workpiece 1 and the electrode 2 (Fig. 1). The capacitor 5 prevents in the specified circuit, the flow of an active short-circuit current through the lines 3 and 4 from the power source after the spark gap between workpiece 1 and the electrode 2 during the discharge of the capacitor 7 or after it.

In Fig. 2, capacitors 10 and 11 are connected in series and operated in succession Switches 20 and 21 are only arranged on the discharge side of the capacitors. Get the leads Direct current or rectified alternating current.

In FIG. 3, the capacitor arrangement according to FIG. 2 is doubled by the capacitors 30 and 31, and Fig. 4 shows a rotating contact arrangement in which the terminals of the capacitors 34, 35 and 36, 37 by the contacts rotating on the circles 38, 39 with stationary contacts arranged on these circles Contacts 38 and 39 are connected, and

809 523/372

by means of a rotating brush holder 40. The positive collector ring is with the workpiece 1 and the negative collector ring is connected to electrode 2. Instead of the brush contacts could also any other known type of contact may be used, e.g. B. Mercury contacts.

According to another embodiment of the invention, the contacts can be replaced by high vacuum tubes, Gas discharge gaps or spark gaps, which may be known Way to be ionized. In these cases, the ionization can be carried out in such a way that in the spark gaps are electrical discharges, inactive substances or ionized gas or steam jets or the like. Are introduced.

With reference to FIG. 2 it should also be mentioned that by the independent control of the respective Arms of switches 20 and 21 both capacitors 10 and 11 simultaneously across the spark gap between Workpiece and electrode can be discharged.

Fig. 5 shows two capacitors 41 and 42 and two oppositely connected rectifier valves 43, 44 to form a voltage doubler circuit. Each capacitor is charged alternately Via the rectifier valve 43 or 44 belonging to it from lines 3 and 4 from an alternating current source. One capacitor is used for one half of the period and the other for the second half loaded. The two capacitors are connected in series with regard to the discharge circuit, see above that the total discharge voltage is twice as large as the charge voltage. By arranging the opposite Directional valves 43. and 44, the electrode 2 is always negative and the workpiece 1 held on positive polarity. The valves 43 and 44 can be of known type, it synchronously operated switches can also be used in their place.

If the spark gap between the workpiece 1 and the electrode 2 is set so that it is bridged when approximately twice the input voltage is reached, then both capacitors discharged at the same time. If, on the other hand, the spark gap is set so that it bridges is when the voltage of the supplied current is approached, then the capacitors unload one after the other.

Claims (5)

Patent claims: 1. Switching arrangement for spark erosion with alternating current or direct current, characterized in that that two or more capacitors (5,7, 10, 11, 41, 42, 30, 31, 34 to 37) in series with the Current source (3, 4) are permanently connected in such a way that during a capacitor discharge period no current can flow from the charging circuit into the discharging circuit to the extent that in the spark gap (1, 2) the spark discharge could transform into an arc discharge. 2. Switching arrangement according to claim 1, characterized in that of two with the power source in series capacitors (5, 7) of one (7) as charge carriers parallel to the spark gap (1, 2) is switched (Fig. 1). 3. Switching arrangement according to claim 1, characterized characterized in that two capacitors in series (10, 11, 30, 31, 34 to 37) with a direct current source are connected and that the capacitors in a known manner by switches (20,21) are alternately connected to the spark gap (1, 2) (Fig. 2, 3, 4). 4. Switching arrangement according to claim 3, characterized in that in each case two capacitors charged one after the other and then discharged together via the spark gap (1, 2). 5. Switching arrangement according to claim 1, characterized in that the capacitors (41, 42) are connected to an alternating current source (3, 4) in a voltage doubler circuit (Fig. 5). Considered publications:
German patent specification No. 226 237. Cited earlier rights:
German Patent No. 967 179. 1 sheet of drawings © 809 528/572 5.58