DE1091253B - Conical nipple connection of carbon or graphite electrodes - Google Patents

Description

The invention relates to a conical nipple screw connection of carbon or graphite electrodes, which is secured against loosening by cementing. A nipple connection by means of a double-conical nipple requires that between the flanks of the thread facing away from the abutting surfaces of the two electron strands there is a certain There is a gap so that there is different thermal expansion of the nipple and the electrode box expansion compensation can take place and there are no box tears or breaks in the electrodes comes. Most of the time, the box cracks appear in the electrode into which the nipple is first screwed is, because so far the nipple was screwed on until it was firmly seated in the first electrode, so that there was no thread play is present between the thread flanks, while the second electrode is only up to the counter-position the two end faces of the electrodes can be attracted. In the second electrode there is therefore a There is a certain amount of thread play between the thread flanks of the nipple and the electrode box.

Various measures are required to avoid this asymmetrical screwing in of the nipple connection known, which ensure a symmetrical screwing in of the nipple connection, d. H. in both Nipple halves pause a thread play.

In the case of a nipple, which is secured against loosening by a putty compound introduced into the thread turns is, the desired thread play is lost again through symmetrical screwing, since the Gaps in the thread flanks are filled with the putty. A cemented nipple therefore leads easier to cracks and breaks in the electrode boxes than a non-cemented nipple. Since you but can not do without the cementing for reasons of security against loosening, the must by the putty caused the risk of cracking due to thermal expansion at different temperatures be eliminated from the nipple and box.

This is achieved according to the invention in that with cemented nipple connections the occurring The effect of thermal stresses at different temperatures between the nipple and the box are restricted by measures that

1. consist in applying the putty only in the tip area of the two nipple halves or

2. when the nipple is completely cemented by using a nipple in a manner known per se Is designed compressible or a smaller coefficient of thermal expansion than the box material in the transverse direction, or

3. In the simultaneous application of the measures mentioned under 1 and 2 have been carried out.

Conical nipple connection
of carbon or graphite electrodes

Applicant:

Siemens Planiawerke

Joint stock company for coal products,

Meitingen near Augsburg

Dr. Waldemar Kaufmann, Dr. Erich Fitzer
and Dipl.-Chem. Hans-Joachim Pfleiderer,

Meitingen near Augsburg,
have been named as inventors

Although a screw nipple connection for carbon or graphite electrodes is known in which between the end faces of the threaded nipple and the bottom of the electrode box each have at least one Safety element in the form of a metal washer or a metal ring made of highly resilient material punched, bent-up tips or with fan-shaped bends is arranged.

This securing element works through its spring action and the fact that it is with his Tips or bends caught in the electrode box and on the threaded nipple. A vibration load such a securing element does not withstand, as the cementing according to the invention does exclusively in the tip area of the two nipple halves. Above all, the blocking effect fails at elevated temperatures by softening or melting the metal parts, while the putty effect according to the invention up to at arc temperatures is maintained.

Furthermore, there is a connection of carbon electrodes, their end pieces provided with bore and internal thread are screwed by appropriate carbon nipples with external thread, known in the one between each face end of the coal nipple and the respective bottom of the bores of the end pieces inserted, electrically conductive plate made of compressible graphite is provided, the diameter of which

009 628/332

knife is approximately as large as the diameter of the bottom of the end pieces.

This measure is intended to provide a higher operating temperature than the previously known embodiments improved conductivity between the nipple and the electrodes can be effected. One This graphite platelet does not cause cementing. Even the aluminum shell that can surround it, melts at operating temperature and does not act as cement.

The invention is explained in more detail below with reference to the drawing.

Fig. 1 shows the nipple connection partially in section;

Fig. 2 shows part of the nipple connection on an enlarged scale;

Fig. 3 shows the nipple connection with cemented nipple end faces.

The two electrodes to be connected are labeled 1 and 2, of which electrode 1 is already is partially used up and should be extended by attaching the electrode 2. The two electrodes have at their ends in the usual way the conical internal thread 4, into which the nipple 3 to Screwed on tightly and then the electrode 2 with the nipple inserted into the thread 4 of the electrode 1 will. Here, the electrode 2 with the nipple 3 is rotated until the end faces 5 are fixed lie against each other. To ensure that the nipple is screwed symmetrically into the two electrodes, Care must be taken that when the nipple is screwed into the electrode 2, the nipple is prematurely against a stop that z. B. is inserted as a paper insert in a thread so that there is still play in the threads.

This stop is formed according to the invention by the putty, which is only at the pointed end of the Nipple is introduced into the electrode box. In this way, the putty creates a firm connection formed between the nipple tip and the bottom of the electrode box. The one in the first Ge-λν-indegänge Putty that penetrates when screwing in does not affect the point because of the pointed end of the nipple the greatest wall thickness of the electrode box is opposite. The elongation forces exerted by the pointed end can therefore be picked up by the electrode box. It is essential that in the equatorial region of the nipple a corresponding expansion possibility of the nipple is retained, as in the Fig. 2 is indicated.

When balancing the nipple, i. H. when screwing in the two nipple halves, certain Tolerances are maintained which, according to previous experience, should not exceed 0.3 mm. These When screwing the nipple into the first electrode box, tolerances can easily be caused by the Braking effect of the cement mass introduced into the box can be achieved.

To secure against loosening of the nipple connection, it is sufficient in many cases to if the putty is only present between the face of the nipple and the bottom of the box is without putty penetrating into the lower threads, as shown in FIG.

A normal nipple 3 with thread play and paper strip spacing 8 is used as embodiment 2 and floor cement 9, with recesses 10 in the box base and in the nipple end faces for better anchoring of the cement body 9 are provided. This cementing is done by inserting a cylindrical, viscoplastic cement compound, which is attached to the cylinder surface with a paper or Foil skin, similar to a sausage slice, is held together, while the end faces with The bottom of the box and the face are in direct contact.

The particular advantage of this arrangement is that it is easy to use in the steelworks. A putty compound, the pitch, is expediently used

ίο contains dissolved in one another with hardening synthetic resin.

In the case of nipple breaks in the strand, it is possible to unscrew the nipple without the box thread to hurt.

As embodiment 3, a totally cemented nipple is selected, which is axially through extending slots is compressible and compared to the box material a smaller coefficient of expansion owns in the transverse direction.

The total cementing of the nipple is particularly advantageous when it is subject to high mechanical loads Electrodes. The end faces can also be cemented. This is when there is a bending load of the electrode string, the voltage is not absorbed by the nipple alone, as was previously the case (danger of the nipple break), but also the two parts of the electrode carry through their cementing. Another The advantage of this total cementing is that when the electrode burns down, it is in the joint until the last remainder of the cemented box can be consumed in the arc. Both As is well known, on the other hand, the box part falls off at the same time as usual, non-cemented joints from the tip, in which no mechanical tension is held on the cone by tearing it open. As a result, 10% Savings— ■ Graphite consumption based on melting performance.

Claims (5)

Patent claims: 1. Conical nipple connection of carbon or graphite electrodes secured against loosening by cement, characterized in that with cemented nipple connections the thermal stresses occurring at different temperatures between nipple and box are restricted in their effectiveness by measures, the 1. consist in applying the putty only in the tip area of the two nipple halves or 2. when the nipple is completely cemented by using a nipple, which is known per se Way is designed compressible or a smaller coefficient of thermal expansion than the box material in the transverse direction, or 3. In the simultaneous application of the measures mentioned under 1 and 2 have been carried out. 2. nipple connection according to claim 1, characterized in that the nipple only on the end face is cemented into the bottom of the box. 3. nipple connection according to claim 2, characterized in that in the box bottom and in the Nipple face recesses (10) are provided for better hold of the putty. 4. nipple connection according to claim 2 and 3, characterized in that the between Box bottom and nipple face to be introduced putty through a paper or Foil skin, similar to a sausage slice, held together on the outer surface as a packaged amount of putty is. 5. A method for producing a cemented nipple connection according to claim 1, characterized in that that the balancing of the nipple with sub-tolerances of 0.3 mm by the braking effect the putty takes place when screwing into the first box. Considered publications:
German Auslegeschriften No. 1 023 534, 1 048 369. 1 sheet of drawings