DE2312603C2 - Device to prevent electrode breakage in electric arc furnaces with an electrohydraulic or pneumatic electrode control - Google Patents

Description

Control spool? and the working cylinder 4, a hydraulic pressure switch 5 is arranged, which is connected to contacts Se and 5 b .

If at the beginning of the melting process the electrode 2 encounters non-conductive material and the weight of the support arm structure including the electrode is supported on scrap, a pressure change occurs immediately in the hydraulic circuit that is proportional to the contact force of the electrode 2. The pressure switch S responds to the change in pressure and closes the contact Se. As a result, the voltage source 16 with diodes 17 is switched directly to the plunger coil as an external voltage. The contact Sb interrupts the voltage signal in the control input. If the predetermined response pressure of the pressure switch 5 in the hydraulic circuit is reached when the electrode is raised, the pressure switch 5 switches off and actuates the contact S b, which switches on the voltage signal again and thus the signal to lower the electrode is available again. At the same time, the contact 5 β interrupts the external signal.
By switching over the "Raise" signal while simultaneously interrupting the "Lower" signal, electrode 2 is constantly brought to the melting material until it is ignited, and the ignition process is repeated. The number of repetitions can be specified as required. At the same time, the hand control

tion can be locked in order to prevent arbitrary intervention in the electrode control. the The duration of the stroke signal can be set using a time relay. If the With the pressure transmitter (S), an optical or acoustic signal can be triggered.

In the example described, a hydraulic control is described; naturally the Device can also be operated by other pressure means.

1 sheet of drawings

Claims (3)

I 2 riaJschicht be avoided. This object is achieved according to the invention in that a pressure switch is provided on the pressure medium circuit of the working cylinder 1. Device to prevent electrical is connected, the electrode control with a contact, which denbrbruch in the arc furnace with an electrical δ with a pressure drop in the working cylinder with the hydraulic or electropneumatic Electrode on non-conductive materials, especially for melting down the signal to lift the electrode directly to the scrap, consisting of a pressure medium control element and when a pre-actuated working cylinder is reached for lifting and lowering, the response pressure in the working cylinder is correct, the Sider electrodes, whose control element interrupts again from a 10 signal for lifting, as well as an electrical one Switching device is adjustable, the contact is connected, which at the same time responds to the voltage signal at the current from the nominal value when the pressure is reduced in the case of deviations in the actual electrode working cylinder The center circle breaks and when the response pressure in the working cylinder is reached, a pressure transducer (5) is connected again to the voltage signal, which welcomes with a contact (Sa) , whereby a signal to lower the electrode is more likely when the pressure in the working cylinder drops is triggered. (4) when the electrode (2) is set down on non- Between the external forces acting on the pressure fluid in the conductive materials, the signal for lifting the working cylinder and the hydro-electrode switches directly to the control element (8) * o static pressure in the working cylinder there is known and when a predetermined level is reached an equilibrium is reached, the pressure of the liquid speaking pressure in the working cylinder (4) interrupting the speed signal of the total weight of the support arm structure including lifting again, as well as corresponding to an electrode. When placing the electrode contact (5 b) is connected, the pressure of the flow in the working cylinder (4) decreases when the pressure is applied to the insulating material. This physical voltage signal at the input of the electrical law is interrupted in the control circuit according to the invention and used when the device is reached. the voltage signal again. The invention is illustrated by means of the schematic switches on, which generates a signal to lower the drawing of an electrical Electrode is triggered. 30 furnace with a combined hydraulic and 2. Device according to claim 1, thereby explained in more detail the electrical control circuit,
indicates that the control element (8) is a device The furnace 1 is with mixed scrap 1 a for pressure detection with signal output. sends. The electrode 2 is in an electrode 3. Apparatus according to claim 1 and 2, there- clamping device which is arranged on the support arm 3, characterized in that the duration of the stroke 35 is held. In the drawing, only one electrode is signaled can be set via a time relay. draws; there are of course several electrodes, which are arranged in the same way on support arms and connected to the voltage source are. The raising and lowering of the electrode 2 with 40 the support arm 3 is effected by a hydraulic working cylinder 4. The cylinder 4 is on one The invention relates to a device for the hydraulic circuit connected to the child of electrode breaks in arcing borrowed motor-driven pump, a Samnielbehälfifen with an electro-hydraulic or -pneumati- ter 20, a pressure vessel 16 and an electromagnetic Electrode control, in particular plunger coil 8 actuated at the table with a hydraulic one Melting scrap, consisting of a pressure booster and a downstream slide 7 medium-actuated working cylinder for lifting and sending. Depending on the position of the slide 7, the ken of the electrodes, the control member of which is either the hydraulic cylinder 4 from a pressure fluid electrical switching device is adjustable, which is supplied at, whereby the lifting of the support arm 3 be deviations of the actual electrode current 50 acts, or it flows into the container 20 where-Vom Setpoint responds. is lowered by the support arm. When starting up the scrap melting process, the electrode 2, which is connected to a non-conductive layer (e.g. , solidified slag in bears, etc.) encounters, 55 converter 10 connected. The electrode current then presses the weight of the support arm structure onto which the electrode voltage is measured via the counter electrode. Because of the non-conductive layer breaks stands 11a and 11b to the required value eindas control signal (voltage signal) is not found together, σ on diodes 14, 146 rectified and men, and the electrode is overall further downwards via resistors ISO, ISb with the adjusted controls until the total weight of the support arm up- 60 setpoint is compared. Which loads on the electrode in the event of a control deviation. occurring differential current is either directly the Since the electrode has only a small mechanical strength plunger coil 8 or increases the slide 7 zugekeit electrode brewing often occurs. The plunger coil 8, which controls the sliding, causes above 7, receives an adapted signal from elec- The object of the invention is to provide a simple electrode current and electrode voltage. A foreign built and reliably functioning device voltage source 16, 17 feeds via switch 19 a and to create, with which electrode breaks at 19 b directly the plunger coil 8 with manual control.
Placing the electrode on a non-conductive mate- In the hydraulic line 23, between the