DE1080709B - Thread pinning in nipple screw connections of graphite or carbon electrodes - Google Patents

Description

GERMAN

As is known, carbon or graphite electrodes for arc melting furnaces are being used in accordance with the progressive Consumption extended by nipple. With the usual conical screw connections that mostly used as a double-conical nipple or a fixed conical attachment on one Have electrode strand, there is a risk that the screw connection loosens and the nipple Electrode falls off, so that serious disruptions in the operation of the arc furnace can occur.

To secure against loosening of the screw connection is therefore through a hole in the box edge a pin inserted which penetrates radially into the nipple body. Will such a radially pinned If the screw connection is unscrewed, an unscrewing torque must be applied that shears off the pin. Is the If the pin has broken, the pin no longer offers any resistance to further untwisting, and that The thread can loosen.

The aim of the invention is to pin the screw connection of carbon or graphite electrodes be improved over the known arrangements with radial pinning, namely to the effect that with a pin of the same dimensions and the same material, the pin breaks leading untightening torque is increased and is retained as the untightening angle increases.

This is achieved according to the invention in that the longitudinal axis of the led through the box edge The pin rests tangentially on the threaded body. This has the effect that in the event of a pin breakage the splinters of the pin get into the thread when unscrewing the threaded connection and make it increasingly difficult to continue turning it up. The undamaged pin increases the buoyancy of the Thread, so that in the event of strong thermal expansion of the box relative to the nipple, pulling it out of the nipple from the box is prevented.

The invention is explained in more detail with reference to the drawing and the result of tests carried out in practice.

Fig. 1 shows in a longitudinal section the previously customary, radially pinned screw connection;

Fig. 1 a shows the radially pinned screw connection in a cross section;

Fig. 2 shows a cross section through the screw connection with a tangential to the thread Pen.

As can be seen from FIG. 1, the double-conical nipple 1 is in the usual way with the two electrode strands 2 and 3 screwed. Through holes in the box edge that run radially, the so-called Nipple pins 4, 5 inserted and penetrate through corresponding Holes in the nipple body. The thread pinning

with nipple screw connections

of graphite or carbon electrodes

Applicant:

Siemens Planiawerke

Joint stock company for coal products,

Meitingen near Augsburg

Dipl.-Ch.em. Dr. Wilfried Hub,

Meitingen near Augsburg,
has been named as the inventor

radial arrangement of the nipple pins 4, 5 can be seen from FIG. 1 a.

In the arrangement according to the invention, in contrast to the known one, the nipple pin 5 is located tangentially in the thread of nipple 1. It is useful to drill through the edge of the box before screwing it together of the electrode strands is generated, and the thread of the double-conical nipple drilled. The threaded pin 5 is then inserted and the hole can be drilled be filled with a little putty before inserting, if the hole is a little larger than the diameter of the pin 5. If one compares the measurement results of the radial pinning with those of the tangential pinning, it can be seen that the opening torque of the nipple at the opening angle Zero is approximately the same in both cases.

For radial pinning, locking pins with a diameter of 20 mm and a length of 200 mm were used. In the case of tangential pinning, a locking pin with a diameter of 20 mm was also used, however of 320 mm length is used. From the table below it can be seen that the torque at the Unscrewing angle of 0 ° is approximately the same in both arrangements. With a larger opening angle, remains at the radial pinning means zero torque while

QOJ 507/35?

it is retained in the tangential arrangement in the test series opposite:

Table 1

Rotation of the two
Boxes against each other

On torque (mkg)

Locking pins 20 x 200 mm, inserted radially

31.8
0
0

29.8
0
0

320 mm, inserted tangentially

28.5 34.8 18.6 19.8 15.0 8.0

0 °

90 °

180 °

Locking pins 20

0 °

90 °

180 °

While the untightening torque for the radially inserted pins drops very quickly to Omkg, for the further unscrewing of the tangentially pinned connection for the further unscrewing still a torque of 15 or 8 mkg are used. Show the tangentially pinned screw connections after screwing on, a nipple thread completely destroyed in the pin plane. When unscrewing the nipple the splinters of a broken pin that is tangential to the thread are fed into the pin guide and thus contribute to the retention of the thread. When unscrewing the thread must therefore completely destroyed in which the pen lies.

Even more favorable measurement results were obtained when the box was torn.

Table 2
Measurement results when the box is torn

Opening torque Locking pins, inserted radially
0 ° 12 mkg 10 ° 0 pen removed 20 ° broke
Φ Locking pins, inserted tangentially
0 ° 40
1 20 ° } 70
- ] higher than
- £ measurable 25 ° 90 ° 180 °

It should be mentioned that the idea of the invention is not only

can be used for conical screw connections of electrodes, but also for cylindrical ones Screw connections of electrodes, although the importance of pinning for the latter is less.

Claims (1)

Claim: Pinning of visual connections of carbon or graphite electrodes, characterized in that the longitudinal axis of the pin guided through the box edge rests tangentially on the threaded body. 1 sheet of drawings © 009 507/352 +.60