SU1725407A1 - Threaded connection assembly of graphitized electrodes - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to increase the strength of the joint by distributing gaps and tensions in the thread. The threaded nipple is screwed into the socket of one of the electrodes and the second electrode is screwed onto it, while the parameters of the elements of the threaded connection are associated with a certain relationship that compensates for the gap between the diameters of the electrode and the nipple at the bottom of the nipple socket. 4 il.

Description

The invention relates to electrothermal, in particular, to the production of graphitized electrodes for arc electrometallurgical furnaces, and can also be used in mechanical engineering, when connecting parts by means of a conical thread.

The aim of the invention is to increase the strength of the connection of graphite electrodes by distributing gaps and tensions in the thread during assembly and after heating the joint.

Figure 1 shows the threaded connection of graphitized electrodes, a general view, in section; figure 2 is a section along the socket of the electrode; in fig.Z - callout in figure 2; figure 4 - geometrical parameters of the thread.

The proposed connection includes connecting electrodes 1 and 2 and a biconical threaded nipple 3. The diameter of the thread in the sockets, measured in the plane of the ends, is larger than the diameter of the thread of the nipple in the main plane by Ad. The thread pitch in the sockets is greater than the thread pitch on the nipple

by At. The angle of the tapering of the threads in the sockets is greater than the angle of the taper of the threads on the nipple by the value (the difference of the angles of taper of the threads of the electrode and the nipple). In order to compensate for the guaranteed clearance in the connection thread in the main plane (A d), the Ad, DG, and DG values are related by

Ad At -n ctgy + LtgAa + 2h (1- tgy v tg OM-ARC where n is the number of threads;

h - the height of the thread profile;

L is the make-up length.

In this case, the gap between the working sides of the turns changes from the end to the bottom of the socket from the value Ad to, at COS a to 0.

The essence of the above dependence becomes clear from the construction shown in Figs. 3 and 4. Its members characterize the effect of each of the parameters

S

; Y SL

five

threads on the size of the gaps between the loaded sides of the coils.

For characteristic combinations of thermal expansion coefficients of the electrode materials and the nipple with operating temperatures, the most efficient state is provided if the diametral clearance Ad 0.2 mm was provided during assembly of the joint in it. To compensate for this gap in the thread length, the values of other thread parameters must correspond to:

At 0.002 mm; Aa 2min; Ay 10 min, where At is the difference between the steps of the thread of the electrode and the nipple.

For internationally accepted electrode threads with a pitch of 35 mm, a glance of a slope (taper) of 9 ° 27 45 and a half angle of a profile at 30 °, the value in the right-hand part of the proposed parameter dependence is 0.114; and in the left part - 0.110, i.e. almost the same.

Based on technological considerations, it is advisable to maintain the specified ratio, fulfilling the thread parameters within: Ad 0.1–0.3 mm; At 0.002-0.010 mm; Ao 2-6 min; Ay 5-15 min, where Ad - the difference of the diameters of the threads of the electrode and the nipple.

The connection works as follows.

The threaded nipple 3 is screwed into the socket of one of the electrodes 1 and the second electrode 2 is screwed onto it. At the same time, for the connections made according to the proposed solution, the diametral gap Ad is guaranteed in the main plane of the connection. So that this gap is not chosen when screwing the electrodes, the thread parameters (step t, angle of taper a and half of the angle of profile y) are selected in accordance with the above dependence, i.e. so that their combination compensates for the amount of clearance Ad to the last thread (at the bottom of the socket).

Thus, in a cold state, the joints in its turns provide gaps on the working sides, decreasing from the ends to the bottom of the socket from Ad tgy COS a to 0. In the same direction, the thread diameter of the joint and, consequently, the magnitude of transverse thermal deformations decrease especially characteristic for use in the manufacture of electrodes.

The biconical nipple, which has a higher temperature and a greater coefficient of thermal expansion, expands upon heating and selects the provided

when assembling gaps, maintaining the specified nature of their distribution.

The proposed numerical values of the thread parameters provide

creation in each turn after heating tensions on the loaded sides of the coils and gaps on the free sides. In this state, the connection is most efficient.

The basis for creating the proposed technical solution was the study of the threaded nipple connection of graphite electrodes using computational methods and physical modeling.

The task of determining the regularities of joint influence on the state of the connection of four thread parameters, four thermal expansion coefficients and a non-uniform temperature field is difficult and time consuming. The result of her decision was the creation of a mathematical model of the threaded connection of the electrodes. The algorithm and calculation program developed using this model allowed

get the regression equation of the required dependence with the geometrical characteristics of the thread as factors. The relationship proposed in the claims is a form of this regression equation in numerical terms. Specific values of the geometrical characteristics of the thread, satisfying not only the requirement of collection in a cold state, but also a given distribution of gaps after heating, were calculated according to a mathematical model using computer technology.

The calculated data were confirmed by physical modeling of the operation of the nipple joint.

The use of the proposed solution allows us to provide rational conditions for the work of the threaded joint of graphite electrodes, reduce the number of their breaks and reduce their consumption per ton of steel produced.

Claims (1)

Invention Formula A threaded connection assembly of graphitized electrodes containing two electrodes with tapered threaded sockets at the ends and a biconical threaded connecting nipple, characterized in that, in order to increase the strength of the connection by distributing gaps and tensions in the thread, the diameter, pitch, taper and angle of the profile electrode and nipple threads are related by the following relationship: Ad ri At ctgy + LtgAa + 2h (1 - tgy l tg OM-SPIRIT where y is half the angle of the thread profile at the side of the coil facing the end of the electrode, degrees; a - angle of the taper of the thread, hail; n is the number of threads; t - thread pitch, mm; h - thread profile height, mm; 0 L is the make-up length, mm; Ay - the difference between the half-angle of the thread profile of the electrode and the nipple, hail; And a is the difference of the angles of the taper of the thread of the electrode and the nipple, hail; At is the difference between the steps of the thread of the electrode and the nipple, mm; Ad is the difference between the diameters of the thread of the electrode and the nipple, mm.  FIG. { FIG. five FIG. 2