SU761588A1 - Method of sheet conveyance at thermal treatment in rolled passing furnace - Google Patents

Description

The invention relates to methods of transporting products in continuous heating furnaces and can be used in metallurgical and other industries.

There is a method of transporting sheets during heat treatment in a roller furnace, which consists in the fact that after soaking in the furnace with a symmetric rocking of the hearth, turning the rollers in the forward and reverse directions to the same angle, one sheet is ejected from the furnace and the other enters the furnace ' [one].

The disadvantage of this method is that at the moment of reversal the rollers are in a fixed position under a load passing through the same plane, which leads to their bending and premature failure. In addition, the known method does not allow uniform heating of the bottom surfaces of the sheets, since with a symmetric shaking after a certain time interval, the sheet surface comes into contact with the roller barrel, returning to its original position, and thereby heating these areas differs from heating the rest of the area, which leads to banded structure, uneven properties at different points of the sheet.

2

There is also known a method of transporting sheets during heat treatment in a roller kiln pass through, including reciprocating movement of them due to 5 reverse of the hearth rollers and heating with a breakdown of the cycle of symmetrical rotation into several stages: forward 180 °, then backward 90 °, forward again 180 ° and back at 270 °. The angle of rotation of the rollers in two cycles forward and back is 360 ° [2].

The disadvantage of this method is that in the process of swinging and stopping the rollers for reversal, the load on them occurs in the same plane, which leads to their bending and premature failure. In addition, with this method of swinging, to ensure that the entire kiln remains in the furnace throughout the furnace, part of the furnace space remains 20 not loaded with sheets, which leads to

to lower furnace performance.

The aim of the invention is to increase the durability of the roller hearth and increase the productivity of the furnace.

25 This goal is achieved by the fact that the reciprocating movement of the sheets in the furnace is performed with an asymmetric amplitude, and the difference between the amplitudes of the forward and reverse swinging is positive and is 15-25 °,

3

and the intervals between the sheets δ penalties set a multiple of this difference.

FIG. 1 shows the scheme of swinging the rollers of the entrance furnace; in fig. 2 —the scheme of changing the position of the sheet on the roller 5 fields.

The method consists in the following.

Sheets subjected to heat treatment, placed on the inlet roller conveyor in front of the roller furnace and load 10 on the roller under the furnace. In order to avoid overlapping adjacent sheets, the latter are loaded with an interval of 0.4-1.0 m. The interval between adjacent sheets is selected multiple of the difference of 15 forward and backward displacement, so that after the number of wiggling cycles required for heating, the end of the outermost sheet is at the end of the furnace. This allows the most efficient use of the effective area of the roller feed.

After the furnace has been fully loaded, the roller furnace is switched on in the swinging mode and the entire charge and the subsequent loaded sheets are heated with 25 rollers with an asymmetric amplitude rocking. An asymmetric amplitude is created due to the fact that the angle of rotation of the rollers in the direction of output is greater than the angle of rotation in the opposite direction, and the difference 30 between them is 15–20 °. The asymmetry of the amplitudes of forward and reverse rocking changes the position of the rollers, the load on them at the time of stopping for the subsequent reversal acts in another plane compared to the plane at the previous stop, which prevents their deflection and premature failure. With asymmetrical swinging after each cycle (direct and 40 reverse swinging), the entire load moves to the output side by 25-40 mm, which allows for a continuous loading process and thereby increase the productivity of the roller furnace. 45

The interval between the amplitude of forward and reverse rocking at 15-25 ° due to the need to change the position of the loading plane of the heated rollers and the frequency of the return of this plane to its original state and is the most optimal. When the swing amplitude difference is less than 15 °, the position of the plane

four

Loading Changes slightly and does not exclude the likelihood of rollers deflection, with a difference of more than 25 ° increases the probability of the rollers returning to the initial position, which also worsens the conditions of their operation.

An example of the method.

In the 60-meter-long roller-type kiln (roller diameter 380 mm), the sheets were heated to normalize. Transportation of sheets and exposure in a furnace for heating produced by the proposed method. The angle of rotation of the rollers with direct rocking was 540 °, in the reverse - 520 °. With a roller diameter of 380 mm, the linear difference of the amplitudes was 80 mm. 9 sheets of steel grade 09G2S with dimensions of 22 × 1800X6000 mm with an interval of 400 mm between them were loaded into the furnace. The wiggle of sheets with the specified mode allowed to produce uniform heating of the sheets to the normalization temperature and to exclude the return to the initial position of the loading roller for more than 20 minutes.

This method allows to increase the durability of the rollers of a through-passage thermal furnace, lengthen the turnaround time and increase the productivity of the furnace.

Claims (1)

Claim The method of transporting sheets during heat treatment in a roller passage furnace, including their reciprocating movement by reversing the hearth rollers, characterized in that, in order to increase the durability of the roller hearth and increase the productivity of the furnace, the reciprocating movement of the sheets in the furnace is performed with an asymmetric displacement amplitude, moreover, the difference between the amplitudes of the forward and reverse movements is positive and is 15–20 °, and the intervals between the sheets in the furnace are set to a multiple of this difference.