SU1282930A1 - Method of cooling and lubricating the unworking part of rolling mill roll - Google Patents

Abstract

The invention relates to .npOKariioNiv production and can be used in the lubrication and cooling of the rolls. The purpose of the invention is to reduce the cracking in the zone of transition of the cervix to the roll barrel. The method involves supplying a coolant to the end surfaces of the roll barrel, and to the surface of its necks - an emulsion lubricant and cooling fluid. The ratio of lubricant and coolant, it is fluid in the mixture, feeding on the roll neck, 1: (8-103 - 40-10) by weight. As a result of using this method, the TeiMjiepaTypa is stabilized in the non-working roller areas, the tretining is reduced, and the life of the rollers is increased. 5 tab. SS

Description

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The invention relates to rolling production and can be used in the lubrication and cooling of mill rolls.

The aim of the invention is to reduce cracking in the transition zone of the neck to the roll barrel.

The method involves supplying a coolant to the end surfaces of the hinge barrel, and to the surface of its necks - an emulsion mixture of lubricant and coolant at a ratio of 1: (40-10) by weight.

To ensure heat removal, it is necessary to know the temperature of the roll at any point. Theoretically, this temperature was obtained by solving a three-dimensional model of the temperature field of a large-sized roll using the finite difference method for different cooling conditions.

The temperature on the surface of the rolls and necks of the roll is determined under industrial conditions during rolling on Slabing 1150 with the TTTs-1 devices and the PIROVAR system.

When the rolls and necks are cooled according to the well-known scheme, the temperature of the necks depends on the temperature of the roll body and the rolling conditions (Tables 1-3).

With an increase in one of the rolling parameters - reduction (table 1), rolling rate (table 2) and temperature of the end of rolling (table 3) - the temperature of the necks increases, and for all values of the operating parameters the temperature of the necks - walks in the critical range (60-80 ° C). With a simultaneous increase in all parameters, a sharp jump in the temperature of the rolls and cheeks should be expected. In such cases, the temperature of the necks exceeds 80 ° C, the textolite inserts are charred, break, there occurs a "nick of necks (mechanical damage from friction of the metal on the metal) and a breakdown of the rolls in satisfactory condition of the working part of the roll barrel. The same phenomenon is observed during long work on necks with a temperature of 60-80 ° C.

In addition, the existing cooling causes uneven temperature distribution along the neck and temperature differences in the transition zone of the neck to the roll barrel (Table 4), which causes uneven wear of the bearings and the appearance of temperature stresses (cracking).

As can be seen from the table. 4, the uneven distribution along the neck is 5-40 ° C, and the difference in the transition zone of the neck into the barrel is 45-120 ° C. For the available temperatures in the zone of cracking, the calculation of the thermal stress by solving the three-dimensional problem of thermoelasticity is carried out. The magnitudes of the stresses given (axial, radial, tangential) taking into account the bending and torsion stresses at a temperature difference of 60 ° C and more are 80-

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95% of the strength of the material rolls (l 65-75 kg / mm). As a result of repeated repetition of the heating and cooling process (millions of cycles over 300 hours of operation), these stresses cause fatigue and destruction of the metal continuity (cracking).

The uneven temperature with existing cooling along the length of the neck is caused by heat coming from the roll barrel, and uneven conditions of friction due to the separate supply of coolant and lubricant at one or two points along the length of the neck. The temperature difference in the transition zone of the neck to the roll barrel is caused by the lack of cooling at the end portion of the roll barrel.

Changing the rolling conditions in the direction of reducing the amount of compression, rolling rate, temperature of the end of rolling is unprofitable from the point of view of productivity and quality of rolled products. It is preferable to change the conditions of cooling and lubrication.

Example. In order to reduce the temperature of the necks and stabilize it at a constant level under varying conditions of rolling, the proposed method was tested at slabing 1150.

Depending on the temperature of the roll at the moment of pause after the metal leaves the deformation zone, coolant was supplied to the front part of the roll barrel and the neck of the roll. On the horizontal part of the roll cheek a cooler was applied as an emulsion mixture of lubricant and coolant.

In the method of mixing the lubricant and coolant occurs before supplying it to the surface of the neck and feeding the emulsion mixture along the entire length of the neck. The supply of a cooler to the end surface of the roll barrel creates an additional cooled zone, which prevents heat from entering the barrel into the neck of the roll. The combined critical cross sections of the roll (geometric dimensions — diameter difference and thermal differential temperature) are separated and the thermal differential retreats deep into the roll barrel, where there is a margin of safety in terms of geometric dimensions (large diameter).

To determine the optimal coolant composition for the necks of the rolls, oil was supplied at a constant flow rate of 1 kg / h, and the flow rate of water was varied from 4 to 45 m3 / h.

Water flow was determined with a BT-80 water meter.

During the time of the study, a constant high rolling rate per slab of about 900 t / h is maintained.

After each hour of servicing, the rolls were stopped, the roll barrel and their necks were turned off, and the surface temperature of the roll necks was measured using a TTTs-1 contact device and a PIROVAR system.

The results of measurements of the surface temperature of the necks of the rolls, depending on the flow rate of the water-oil mixture at a constant oil consumption, are given in Table. five.

With less than 1: (8-10 - 40-103) lubricant consumption, the temperature of the roll necks gradually increased, with a larger one, it did not change.

Thus, as a result of theoretical calculations and industrial research, the optimum ratio of the components of the emulsion mixture of lubricant and cooling liquid to it, equal to 1: (8-10 - 40-10) by weight, has been determined. The ratio found with the proposed method of supplying the cooler and the operating mode of the non-operating part of the roll reduces the temperature

roll necks and stabilize it at a level of 30-45 ° C under variable rolling conditions, reduce cracking and increase roll resistance by 20-30%, reduce downtime for emergency transshipments.

Claims (1)

Invention Formula The method of cooling and lubrication of the non-working part of the rolling rolls, including the supply of lubricant and cooling fluid to its surface during the rolling process, characterized in that, in order to reduce cracking in the transition zone of the neck into the roll barrel, a cooling is applied to the end portion of the roll barrel. liquid, and on the surface of its necks serves an emulsion mixture of lubricant and cooling liquid at a ratio of 1: (8 10 -40-10) by weight. Table 1 The dependence of the heating of the necks of the rolls on the amount of compression of the slab in the rolls The amount of compression, mm 30 40 50 60 70 The temperature of the necks, with 61 67 73 79 85 table 2 The dependence of the heating of the necks of the rolls from the rate of rolling The amount of pauses, from 2000 1600 1200 800 400 Neck temperature с5056 62 68 74 Table 3 The dependence of the heating of the necks of the rolls on the temperature of the end of rolling slabs End temperature rolling 1140 1160 1180 1200 1280 The temperature of the necks, s66 67 70 75 82 Table 4 The unevenness of the temperature distribution of the neck of the roll along its forming with the existing cooling Neck temperature, ° С Barrel temperature, s The butt at Galtel The butt at The depth of the top-top-necks nostinesti 45-65 50-85 180-240 95-170 ., ... „-,.-..------., - - - - -. - - - - - - - - - - Table 5 Water consumption for the preparation of water-oil mixture, m3 / h 4 5 6 7 7,5 8 10 20 30 40 42 45 The surface temperature of the necks of the rolls, с82 76 63 51 47 45 45 39 34 30 30 29