DE2002362B2 - DEVICE FOR ELECTRICALLY CONTROLLING THE DEPTH OF THE LIQUID SLAG IN ELECTRIC SLAG WELDING - Google Patents

Description

It is also known that the level of the molten bath is relatively large and uneven

by acting on the speed of the sweat- fluctuations resulted.

device and the regulation of the voltage of the welding Since it was found that the fluctuations of the

zone by acting on the open circuit voltage of the depth of the slag layer by fluctuations' les

To regulate power source The inventors also have to display a regulation 5 welding current

the depth of the slag layer independently of Schwan found that the depth of the slag layer was accurate

sound of the feed current is not possible, so that one can be adjusted and set if the

Incorrect adjustment of the slag layer depth for details of the fluctuations in the welding current

Fluctuations in the supply current, which are not uncommon, can be determined,

often unavoidable. 10 In the course of their efforts to develop a

The object of the invention is to provide the automatically working adjustable adjustment devices

the described difficulties and an auto-calculation for the depth of the slag layer have the

Automatically working electrical device to see-finder tries to work during the welding process

Ren rules of the depth of the liquid slag layer to occurring fluctuations in the welding current

create that reinforce each type of electroslag welding, for example by a differentiating

ßens independent of welding current fluctuations on the circuit. The results achieved here are in

Reason for normal changes in the mains current F i g. 3 to 5 shown,

is applicable. It was found that at a favorable depth of the

To solve this problem, the invented slag layer is torn as a curve of the weld dung has only small peaks in a device of the aforementioned 20 current, as shown in FIG. 3 shows. Art suggested that the detector be a change from F i g. 4 shows, however, that the course of the Electricity corresponding to the welding current strength at a shallower depth of the slag layer Irish signal picks up and its threshold value has the larger peaks. If the depth of the slag-typical fluctuations in the welding current within the layer is even smaller than according to FIG. 4 is, will, a permissible 1 current range is set, so that 25 as FIG. 5 shows the current peaks are still significant the feeder for the flux only then actuates larger and more irregular.

If the fluctuations in the welding current have been found on the basis of these results, the value for the permissible fluctuations clerSdilaclj; - that the supply device for the flux or other exceed layer depth. In this way the welding equipment is operated properly and the one you want Automatic supply of the flux, regardless of the 30 depth of the melted slag layer, correct influx fluctuations, d. h .. the flux supply can only be regulated if you have the average then changed if due to an impermissible deviation of the current peaks at the gate current '<rice des Regarding the lacquer layer depth a regulation is necessary thyristor, because in this way one will. The pre-current value only needs to be set once at the correct depth of the slag layer direction necessary, which is then given the same in all cases, which works less than the lower limit of the trigger-wise. current of the thyristor, while incorrect

In the drawing, one embodiment of the g _3r depth of the slag layer is receiving a current that

Invention on the basis of diagrams and an electrical the lower limit of the tripping current of the thyristor

Irish circuit explained in more detail, namely shows exceeds.

Fig. 1 is a diagram of a rectified current 40 die for adjusting the depth of the slag layer

curve which, with the depth lying in the favorable range, of the during the welding process according to the

The circuit used in the invention is shown in FIG. 6th

F i g. 2 shows a diagram of a rectified current. The circuit contains an unloaded

curve that was recorded as the depth of the cut-off relay 1 for switching off the electrical

Slag layer was relatively small, 45 current and an adjustable resistor 2 to the

F i g. 3 a diagram of the Kuivc of the gate current value of the transformer in the primary winding

a thyratron or thyristor, which can be set at a cheaper current input. The Ab-

Ticfe the slag layer was added, switching relay 1 is provided with a contact switch 3,

F i g. 4 shows a diagram of the curve of the current to which a rectifier 4 is connected. Except cincs Thyratrons or thyristors, which are at relative 50 a blasting resistance 5 and an excessive shallow depth of the slag layer aufcrrüin- equal condenser 6 is provided, which is parallel to men were ^ e, the primary winding of a transformer 7 switched

F i g. Figure 5 is a diagram of the curve of the gate current used to vary the welding current

a thyratron or thyristor, which can still gc-. To the 'xkundärseitu of the transformer 7 is

lesser animals of the slag layer as shown in FIG . 4 55 a rectifier 8 is connected. Behind this

was added, and rectifier 8 is a resistor 9 to

6 shows an electrical circuit for a according to regulating the gate current of a thyristor 10.

The automatic welding machine equipped with the invention is a relay 11 for an electromagnetic feed

maschinc. driving device provided. To regulate the the

When measuring the variations of the welding current supply device 60 electromagnetic added during a Elektroschlackcschweißvorganges wur- current, a variable resistor 12 is provided to the curves f i g. I and 2 added. which is connected to a coil 13 of the electromagnetic supply-The curve of the Sehweißstromes device shown in FIG. The relay 11 13t was also measured when the depth of the slag layer gave that with a contact switch 14 while having correct value. The curve recorded shows 65 a resistance 15 is provided in order to allow uniform fluctuations in the reel 3. The in F i g. 2 to regulate the current flowing through it. Behind the resistance curve, however, it was recorded when the stand 15 there is a contact switch of a relay below the depth of the slag layer was relatively small, explained. Furthermore is a rcejlhnmr VJiAm-.

stand 17 provided to the in the relay 11 and the coil 13 of the electromagnetic feeder to regulate the electricity supplied. In addition, a rectifier 18, a load resistor 19 are a Compensation capacitor 20, a capacitor 21 serving as a time delay and one for regulating the Delay time and the current supplied to the relay 23 serving resistor 22 is provided. In the end are still a contact switch 24 for the electromagnetic feeder and an electrical one Stromc | iiclle for the relays II and 23 provided.

The general device works as follows: The applied welding current is regulated by the adjustable resistor 2 and by means of the Rectifier 4 converted into a rectified welding · 5 current. The rectified welding current is then about the load ivvideistand 5 and the Equalizing capacitor 6 is applied to the transformer 7 so that the welding current from the transformer 7 is converted into an electrical signal with a differentiated waveform.

This having a differentiated waveform, from the transformer 7 erzcug'.c electrical signal is rectified by the rectifier 8 and sent to the gate circuit of the thyristor 10 passed, so dai.i the thyristor remains conductive and thus there, ι '.- l..i.,.: actuated. When the relay 11 is operated in this way; is that it opens the contact switch 24, begins the Capacitor 21 corresponds to one by its capacitance, the resistance value of resistor 22 and the resistance value of the relay 23 to discharge certain constant.

When the capacitor 21 is discharged so far. that the discharge current is less than the lowest value of the actuation current. the contact switch 16 is opened so that the thyristor is non-conductive.

The operating time of the electromagnetic feeding device can be controlled by means of the capacitor 21 and of the resistance of the relay 23 can be set.

The invention is explained further below with the aid of an example.

example

From two electroslag welding machines with a melting point Nozzle was equipped according to the present invention. With both machines two workpieces each welded together using the electroslag welding process under the following conditions, each workpiece made of mild steel or welded steel with a thickness of 25 mm and one Length of 700 mm existed and where / wipe there was a welding gap of 20 mm wide between the workpieces that were connected to each other.

Sweat (.! Condition, lines:

Electricity used. . Direct current. 500 amps voltage 33 to 35 full

Dimensions of the consumable nozzles used:

Outside diameter 10 mm

Inner diameter 4 mm

Length 850 mm

Diameter of the used
Welding wire 2.4 mm

Chemical components of the welding wire used

C 0.07

Mn 1.80

Si 0.30

Mon 0.15

Chemical composition of the flux used

SiO, 3S

MnO 21

CaO 19

CaF ₂ 10

The time required in the comparison tests to weld the workpieces together on five each Points results from the following table.

Working hours of
machine

Preparation time
for the weld

Total
Sweat

Usual weld

Welding according to the invention

125 minutes
125 minutes

150 minutes
35 minutes

275 minutes
160 minutes

From this example it follows that when applying the Ert.ndung to the electric slag welding process no monitoring of the progress of welding by a person is necessary. but the tail: .ung is carried out completely automatically, so that the welder himself during the welding process can already deal with the next welding process with another welding machine. At the known Elektroschlaekeschweiken, however, it is necessary, the entire welding process constantly supervised by a person, which undoubtedly creates higher labor costs. Therefore, according to the Establishment for carrying out welding activities required time can be reduced significantly, while the preparation or set-up time for a subsequent Schwei livoi went on at least the Half are reduced ki.nn.

In addition, according to the invention, the depth of the liquid slag cannot fall within a range of 50 mm - or -10 mm can be adjusted automatically. There were no abnormalities in the appearance of the weld or weld bead thus produced X-ray examination of the joints and in the mechanical properties of the deposited Metal found. In comparison with weld seams produced according to the usual working method or weld beads were shown by the welding bead produced according to the invention as well as the mechanical one Property of the deposited metal only a slight variation and the same quality at all Spark of the established connection.

Although in this embodiment; part of the invention the depth of the liquid slag cannot be regulated in the above range, it can

can also be changed and regulated according to a value of the welding current, the thickness of the workpieces to be connected and / or other factors.

The present invention is therefore effectively capable of adjusting and maintaining the depth of the Ensure liquid coating layer in the desired framework Im.

As explained above, this depends on

{finding not only from the difference in fluctuations in the welding current, but from the strength the fluctuations of the welding current so that The feed device for the flux or welding agent is operated afterwards.

Therefore, regulating the depth of the slag

Not according to the invention essentially free from : fluctuations in the welding current, which can result from the fact that the in the primary winding of the

Transformer introduced current or the welding current fluctuates, which has rarely occurred in welding technology up to now. Further, when the invention is used in connection with mil

Welding currents are applied, the falling eigen own shafts, an increase in the tension used for heavy Ben leads to a decrease in the Amperage. If, however, the invention in connection with welding currents with increasing intrinsic

ίο is applied or tending to increase the welding current will be changed significantly without changing the voltage step.

Therefore, according to the invention, Veriinde

rungs of the Schweinstrom can be used. Dii Invention is therefore suitable to the device / in Applying flux or welding agent to operate on the basis of this phenomenon.

For this purpose 2 sheets of drawings

109 585/30

Claims (3)

1 2 place between two workpieces. Patent claims If a defect in the weld seam has arisen, one has to compensate for this defect with great effort and time and the incomplete 1. Rework the device for the electrical control of the depth of 5 upcoming welds. of the liquid slag layer in electroslag - The depth of the slag layer can be accordingly weld according to the depth of experience and skill of the welding changes this slag layer, in which the ßers are somewhat regulated. Have in practice However, many welders do not have this experience and experience changes in depth corresponding to the electrical signal is picked up by a detector and the io physical dexterity, so that for a long time The supply of flux controls the need for an automatically working pre-drawing, that the detector is in the change direction for setting or regulating the depth of the There is an elec- tric slag layer corresponding to the welding current strength. tric signal and its threshold value. To meet this need, the The usual fluctuations in the welding current 15 are rich in methods for automatically regulating the depth Proposed within a permissible current range one of the slag layer. One of these introduces so that the supply device for the flux is an electro-slag welding machine is then actuated when the fluctuations ne, the two water-cooled copper shoes or copper des Welding current has the value for the permissible plates, which fluctuations on both sides exceed the slag layer depth. 2o binding point are arranged vertically displaceable 2. Device according to claim 1, characterized in that they are shifted and moved in the course of the welding process, indicates that the detector is connected to the secondary Here is a so-called mechanical switch in winding of a transformer (7) connected to an electrical connection between one of the is, which by a rectifier (4) equal copper plates and a feed device for the directed welding current provided in an electrical signal 25 flux or other welding means. at converts that of another rectifier of this electric screw welding machine is the depth (8) gleicligerich ° t and set in the gate circuit of one of the slag layer that the Part of the detector hildenden thyristor (10) a mechanical switch is operated as soon as the depth is given, which reaches a certain value when the slag layer is exceeded Threshold value of the changes d -r welding current- 30 ha ', so that the power supply to the supply device strengthen a relay (11) connected in series with it, for which the flux is interrupted and this device actuated so that the supply device (13) for flux cannot emit any further flux, controls. as long as the slag layer is still the predetermined 3. Apparatus according to claim 1 or 2, characterized in depth. characterized that to the relay (11) via a 35 If you have the same electrical circuit at Switch (24) a time delay (21) connected Elektroschlackeschvissverfahren with melting after the switch (24) has been opened, the nozzle in an electro-slag provided for this purpose a certain time the thyristor (10) and welding machine with two water-cooled fixedwith it the relay (11) switches over. Used the copper plates, it has proven impossible 40 pointed out that flux or other welding agents should be topped up in the correct quantities in the slag layer, if you consider the depth of the slag layer, from that a parameter or a word can be changed at will during the welding process, continuously changing the length of the weld is checked and recorded. In order to determine the depth of the slag for this special purpose The invention relates to a device for keeping the electrical layer at a constant value, the experienced welder must control the depth of the liquid slag layer as the depth of the slag layer changes step by step, 50 by step Determine along the weld seam, which is called the one corresponding to the depth changes, undoubtedly very uneconomical and impractical.
Trical signal recorded by a detector So far, the applicant has for controllable setting and controls the supply of flux. the depth of the slag layer the feed device The 1: lcktros; hlackcschwcißcn is a welding for the flux so that it ws according to the Welding joint between two parts to be connected to one another, the measured difference between the normal parts to be connected, a flux or other welding current intensity and a welding material with a reduced depth and a welding wire from the slag layer corresponding to the increased welding above. After the ignition melts the amperage is controlled. With such a pre- welding wire from and fills the welding joint, with direction it has been found that the normal value of a layer of liquid flux, ie the slag, the welding current intensity is changed when the layer in the layer is above that of molten metal of the primary winding of the welding current transformer is the top layer of the weld seam. flowing stream fluctuates. It is therefore difficult to determine precisely the difference between the normal amperage of the depth of the slag layer during the entire 65 and an increased amperage of the welding current for the finished electroslag welding process. To solve this problem, the weld is of the utmost importance, as it otherwise requires a complicated apparatus, which inevitably makes the welding process costly if there is a failure in the uniformity of the joint.