RU2287384C1 - Bar rolling stand rolls cooling method - Google Patents

Abstract

FIELD: rolled stock production, possibly cooling grooved rolls in bar rolling mills.

SUBSTANCE: method comprises steps of feeding from jets to roll grooved passes fan-like mutually overlapping streams of cooling water. Water is fed to jets with outlet openings having diameter 5 - 9 mm under pressure 0.9 - 4.5 at. Cooling is performed by means of water streams at opening angle 50 - 70°. Flow rate of water supplied to outlet zones of roll grooved passes exceeds by 1.5 - 3.2 times flow rate of water fed to mean part of roll grooved passes. Cooling water is fed to roll grooved passes at outlet side of stand; at inlet side of stand roll grooved passes are dried by compressed air streams.

EFFECT: enhanced strength of rolls due to possibility of equalizing wear degree of roll along contour of roll grooved pass.

3 cl, 6 ex, 1 tbl

Description

The invention relates to rolling production and can be used on section rolling mills for cooling rolls with calibers.

A known method of cooling the rolling rolls during the rolling process, comprising supplying cooling water to the surface of the rolls from the exit and entry of the metal into the crate, the ratio of the maximum and minimum angles of supply of the cooler to the surface of the roll and roll is set in the range (1.4-3): 1 , the length of the supply zone of the cooler is set to no more than 5 lengths of the gripping arc on the roll and π / 2 on the roll [1].

A disadvantage of the known cooling method is that when cooling water is supplied to the roll and the strip on the inlet side of the stand, as a result of the vapor-explosion effect in the deformation zone, the roll surface is destroyed, and the roll resistance decreases.

There is also a known method of cooling rolls during hot rolling, in which cooling water is supplied to the roll by jets from the output side of the stand. At the inlet side of the stand, the remaining cooling water is removed from the roll using two plates located one above the other [2].

The disadvantages of this method are that the cooling of the roll, on the barrel of which streams are made, is inefficient. In addition, the plates on the input side of the stand do not allow to drain the surface of the roll. As a result of this, the resistance of rolls of the rolling mill decreases.

The closest in their technical essence and the achieved results to the proposed invention is a method of cooling rolls of a rolling mill stand, according to which fan-shaped mutually overlapping jets of cooling water are fed from nozzles (tips) to streams and beams forming gauges. The rest of the barrel is cooled to a lesser extent [3] - prototype.

The disadvantage of this method is that it does not provide effective cooling of the calibers and their subsequent drainage, which leads to a decrease in the resistance of the rolls. In particular, the streams that are most susceptible to wear (side walls) of the stream cool less intensively than the middle part of the gauges.

The technical problem solved by the invention is to increase the resistance of the rolls.

To solve the technical problem in the known method of cooling rolls of a rolling mill stand, including feeding from nozzles to streams forming calibers, fan-shaped mutually overlapping jets of cooling water, according to the proposal, water is supplied to nozzles with an exhaust nozzle with a diameter of 5-9 mm under a pressure of 0.9- 4.5 atm., Cooling is performed by water jets with an opening angle of 50-70 °, while the flow rate of water supplied to the outlets of streams is 1.5-3.2 times higher than the flow rate of water supplied to the middle part of the calibers. In addition, cooling water is supplied to the streams from the output side of the stand, and on the input side of the stand, the streams are drained with compressed air jets.

The essence of the invention is as follows.

Water supply to nozzles with an outlet nozzle of 5–9 mm under a pressure of 0.9–4.5 atm. and cooling of streams with fan-shaped streams of water with an opening angle of 50-70 ° provide the most intensive heat removal from streams. At the same time, the supply to the outlets of streams of 1.5–3.2 times increased amount of water makes it possible to lower the temperature of the sections most loaded by temperature and work of friction forces. This reduces the rate of wear of the streams, making it uniform along the contour of the stream. The supply of cooling water to the streams from the output side of the stand allows to take away more heat due to a higher temperature gradient from the overheated surface of the roll leaving the deformation zone and to reduce heat transfer deep into the roll. Subsequent drainage of the streams by jets of compressed air on the inlet side of the stand will exclude water from entering the deformation zone and the formation of a vapor-explosive effect in it, which contributes to the destruction of the stream surface.

It has been experimentally established that if the outflow nozzle has a diameter of less than 5 mm and water is supplied under a pressure below 0.9 atm, the blow force of the fan-shaped jet against the cooled surface of the stream is insufficient to effectively break through the steam jacket and take heat from the roll. In addition, there is a decrease in cooling water consumption. This leads to overheating of the roll and accelerated thermal wear. An increase in diameter of more than 9 mm and pressure above 4.5 atm. leads to an excessive consumption of cooling water and supercooling of the rolled profile, which is unacceptable.

A decrease in the opening angle of less than 50 ° reduces the cooling efficiency and, for water to cover the entire surface to be cooled, requires the nozzle to be removed from the roll. In this case, the kinetic energy of the jet is lost, the temperature of the roll and its wear increase. An increase in the opening angle of more than 70 ° leads to a decrease in the uniformity of cooling of the roll surface in the central and peripheral parts of the fan-shaped stream of water. This reduces roll resistance.

If the flow rate of water supplied to the outlets of the stream exceeds the flow rate of water supplied to the middle part of the caliber by less than 1.5 times, then there is increased wear of the outlets. If the specified cost ratio is more than 3.2, then this will increase the unevenness of the wear of the caliber, because its middle part will wear out more intensively. As a result, the roll resistance decreases.

Method implementation examples

Cooling water is supplied to the rolls of the first stand of the wire mill 150 with an open box caliber formed by streams of trapezoidal section of the upper and lower rolls. Nozzles for water supply are installed on the output side of the stand and have a working channel diameter d = 7 mm. The angle of the nozzle stream is φ = 60 °.

When rolling a billet of 100 × 100 mm square section heated to a temperature of 1230 ° C from grade 45 steel in the first stand, fan-shaped mutually overlapping jets of cooling water are fed to the rolls. Cooling water is supplied to each stream from 5 nozzles: a pair of nozzles is directed to one of the outlets, one nozzle is directed to the middle part of the caliber, and another pair of nozzles is directed to the other outlet. Due to this, the flow rate of water supplied to the outlets of the stream is N = 2 times higher than the flow rate of water supplied to the middle part of the caliber. The water pressure in the manifold, in which all 5 nozzles are installed, is P = 2.7 atm.

In order to drain the streams on the rolls before they come in contact with the rolled metal, on the inlet side of the stand, the streams are blown with compressed air from the workshop line. The jets of compressed air blow off the remaining moisture and eliminate the vapor-explosive effect in the deformation zone.

Due to the cooling of the rolls of the rolling mill according to the proposed modes, their mass-average temperature does not rise above t = 70 ° C, the wear of the rolls decreases and its uniformity along the streamline improves. As a result, the specific consumption of rolls decreases to Q = 0.76 kg per ton of rolled metal.

Implementation options of the proposed method and indicators of their effectiveness are shown in the table.

From the data presented in the table, it follows that when implementing the proposed cooling method (options No. 2-4), an increase in the resistance of rolls with gauges of a rolling stand is achieved, the temperature of the rolls is minimal. In cases of transcendental values of the declared parameters (options No. 1 and No. 5), the roll resistance is reduced, an indirect indicator of which is the higher temperature of the rolls. Also, the low roll resistance at their higher temperature takes place when implementing the prototype method (option 6).

Table
Options for implementing the proposed method and their effectiveness No. p / p D
mm R,
atm φ, deg N times t
° C Q,
kg / t one. four 0.8 48 1.4 98 0.99 2. 5 0.9 fifty 1,5 75 0.79 3. 7 2.7 60 2.0 70 0.76 four. 9 4,5 70 3.2 72 0.78 5. 10 4.6 75 3.3 84 0.92 6. negl. 3.0 negl. N <1.0 120 1,1

Technical appraisal and economic advantages of the proposed method consist in the fact that with a regulated pressure, diameter of the nozzle and the opening angle of the jet of cooling water, the efficiency of heat removal from the surface of the stream increases. An increase in the flow rate of water supplied to the outlets of the stream by 1.5-3.2 times when using all the proposed cooling parameters ensures equalization of the wear of the roll along the contour of the stream. In addition, the supply of cooling water to the streams on the outlet side of the stand and the drying of the streams with compressed air at the inlet exclude the appearance of a vapor-explosive effect in the deformation zone. Due to this, the resistance of rolls with gauges of the rolling stand is increased.

Implementation of the proposed cooling method will increase the profitability of the production of long sections of rolled products by 5-7%.

Information sources

1. Autosvid. USSR No. 1227275, IPC В 21 В 27/10, 1986

2. Japanese application No. 57-103718, IPC B 21 V 27/10, 1982

3. N.A. Budagyants, V.E. Karsky. Cast rolls. M .: Metallurgy, 1983, S. 60-61 - prototype.

Claims (3)

1. A method of cooling rolls of a rolling mill stand, comprising feeding from nozzles to streams forming calibers, fan-shaped mutually overlapping jets of cooling water, characterized in that the water is supplied to nozzles with an exhaust nozzle with a diameter of 5-9 mm under a pressure of 0.9-4.5 atm., cooling is performed by water jets with an opening angle of 50-70 °, while the flow rate of water supplied to the outlets of streams is 1.5-3.2 times higher than the flow rate of water supplied to the middle part of the calibers. 2. The method according to claim 1, characterized in that the cooling water is fed to streams from the output side of the stand. 3. The method according to claims 1 and 2, characterized in that on the input side of the stand, the streams are drained with compressed air jets.