JPS5829168B2 - Rolling oil supply method in cold rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for supplying rolling oil to a cold rolling mill, and more specifically, an emulsion liquid containing rolling oil at a low concentration is supplied to the exit side of each stand of a cold rolling mill as a roll coolant. In addition to supplying and circulating it, a part of it is extracted and further added with rolling oil to create an emulsion containing a high concentration of rolling oil, and this is applied to the entrance side of each stand of the cold rolling mill as a rolling lubricant. The present invention relates to a method for supplying rolling oil to a cold rolling mill in which rolling oil, etc. in scum generated in an emulsion liquid circulated as roll coolant during supply is recovered and this rolling oil is reused.

Generally, in cold rolling mills, an emulsion liquid containing rolling oil is supplied to the inlet side of each stand as a rolling lubricant in order to reduce the frictional resistance between the work rolls and the IJ tubes during rolling. In addition, the temperature of the roll and strip increases due to plastic processing heat, deteriorating the shape of the strip and causing surface defects on the strip surface.
An emulsion liquid containing water or rolling oil is kept at a low temperature and supplied to the exit side of each stand to cool the rolls and strip.

In addition, the lubricating method for cold rolling mills is usually carried out by a circulation method or a direct method. The emulsion of low-concentration rolling oil is supplied and circulated to the side and outlet side, and this low-concentration rolling oil emulsion serves both as a rolling lubricant and as a roll coolant.

In addition, in the latter direct method, an emulsion liquid containing a high concentration of rolling oil is supplied to the inlet side of each stand as a rolling lubricant, and cold water is supplied as a roll coolant to the outlet side of each stand. All liquids are disposed of without being recycled.

However, these lubrication systems also have problems with the rolling oil consumption rate, wastewater treatment equipment, etc. As a result of research, the inventors have found that: 1) rolling oil is effective with a low rolling oil consumption rate; We have proposed a method of supplying rolling oil that can be supplied efficiently and does not require wastewater treatment equipment.

First, in this rolling oil supply method, similar to the circulation method, a low-concentration rolling oil emulsion is supplied as roll coolant to the exit side of each stand of a cold rolling mill, and this is circulated. A part of the emulsion liquid is extracted, new rolling oil is added to it, and this highly concentrated rolling oil emulsion liquid is supplied to the entrance side of each stand as a rolling lubricant, At this time, the rolling oil usually contains various oils and fats as well as oiliness improvers, emulsifiers, extreme pressure additives, etc., as in the conventional example, and these components are dissolved in emulsion VC@ in hot water, It is used as an emulsion liquid in roll crands and rolling lubricants.

In this rolling oil supply method, the rolling lubricant function is sufficiently enhanced with a small amount of rolling oil, and the cooling function is sufficiently enhanced with a low-concentration rolling oil emulsion liquid that is circulated as a roll coolant. The concentration of rolling oil emulsion liquid is
Since it is returned to the roll coolant circulation system, the consumption of rolling oil can also be significantly reduced.

In this case, the concentration of the highly concentrated rolling oil emulsion liquid is such that the rolling force changes depending on the hardness of the material to be rolled, the reduction ratio, the rolling speed, etc., and the concentration is such that the rolling force can be maintained at an appropriate level in order to correspond to these changes. It is necessary to maintain this concentration at
Affected by the concentration of rolling oil in the roll coolant.

However, the low-concentration rolling oil emulsion that is circulated as roll coolant needs to be kept as low as possible in order to enhance its cooling function. It floats as scum and the rolling oil in the emulsion liquid is consumed.

For this reason, during circulation as roll coolant, the concentration of rolling oil gradually decreases by the amount that is separated as scum. However, in addition to causing an increase in the rolling oil consumption rate, it also affects the concentration of the highly concentrated rolling oil emulsion liquid.

The scum is a mixture of iron powder generated during rolling and rolling oil, which is separated from the rolling oil that is present in an emulsion state and floats on the liquid surface.

Therefore, scum contains a large amount of oil and fat, but if the temperature inside the roll bite is high, part of the emulsion-like rolling oil undergoes phase inversion and scum is formed. Therefore, the scum is in the form of an inverted emulsion.

Therefore, it is very difficult to re-emulsify and dissolve the scum in the form of an inverse emulsion into the emulsion liquid, and usually an agitator, pump, etc. is used in the circulation system to provide a stirring action to allow the scum to float. At times, scum is actively separated from the normal emulsion and only the normal emulsion shore is circulated to continue stable rolling operations.

Therefore, the present inventors analyzed the composition of scum in order to examine the possibility of effectively utilizing the fats and oils contained in the scum, and compared the ('tJ composition with the composition of a new rolling oil). The results are shown in Table 1.

As is clear from Table 1, the oil and fat content in the scum is not much different from new rolling oil in terms of saponification number and oxidation, and apart from high iron and ash content, there is almost no deterioration as a fat or oil content, and it can be used as a lubricating oil. It turns out it's possible.

The present invention was established in line with the above points, and specifically, the present invention actively removes fats and oils from the scum generated when the emulsion liquid of low-temperature rolling oil, which is circulated as roll coolant, is kept at a low temperature. We propose a method for supplying rolling oil in which the recovered fats and oils are added to a high-concentration rolling oil emulsion liquid that is recovered and supplied as a rolling lubricant for effective use.

That is, the method of the present invention circulates a low-concentration and low-temperature rolling oil emulsion liquid as a roll coolant that is injected to the exit side of each stand of a cold rolling mill. New rolling oil is added to the extraction section to make a highly concentrated emulsion liquid, and if necessary, it is heated and pressurized and then sprayed as a rolling lubricant before the biting of each stand, and then added to the circulating emulsion liquid. After collecting the scum generated in the emulsion of rolling oil that has merged into a low-concentration and low-temperature emulsion, foreign substances such as iron and ash contained in this scum are removed, while oil and fat are separated from water. Thereafter, this oil and fat, if necessary, an emulsifier, etc. are blended, and this is added as part or all of the new rolling oil to be added to the extraction section.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

Furthermore, Fig. 1 is a flow sheet showing the circulation system of the emulsion liquid of low concentration rolling oil and the extraction system of the emulsion liquid of high concentration rolling oil in the method Ki- of the present invention, and Fig. 2 is a flow sheet showing the scum recovery system. It is a flow sheet showing an example.

First, by pressing the VC button in Figure 1, the emulsion liquid of low concentration rolling oil (hereinafter simply referred to as low concentration emulsion) as a roll coolant is pumped up from the coolant tank 13 at a low temperature by the pump 7, and then supplied to the filter 8. The foreign matter is then removed.

Thereafter, the low concentration emulsion is supplied from the cooling nozzle 5 through the pipe 3 to the exit side of the stand 1 of the cold rolling mill, and the roll and the strip 2 are cooled.

In addition, a part of the low concentration emulsion is extracted through the pipe 10, and into this extraction part, new rolling oil from the pipe 11 is added to the mixing tank 16 along with recovered rolling oil or recovered rolling oil from the scum as described later. are added, and these are stirred by an agitator 17 to create a uniform emulsion liquid of high concentration rolling oil (hereinafter simply referred to as high concentration emulsion).

This highly concentrated emulsion is usually heated in the mixing tank 16 by a heater (not shown), and pumped 6
After being pressurized by VC, it is supplied to the strip 2 from the nozzle 4 into the stand 10 of the cold rolling mill at high temperature and high pressure.

In addition, the drained liquid from each stand 1, that is, both emulsions supplied from the nozzles 4 and 5, is returned to the return section 14 of the coolant tank 13 through the return pipe 9, where the liquid level decreases. Water for compensating the amount is supplied through the pipe 12, while being stirred by the agitator 17,
A uniform low concentration emulsion is prepared.

In this case, the scum 25 floats on the surface of the return section 140, and usually a skimming device 23 or the like is provided, and the scum 25 is discharged out of the system through the piping 24.
A uniform low-concentration emulsion containing relatively little scum flows into the feed section 15 of the coolant tank 13, but in the present invention, oil and fat are recovered from the scum and an emulsifier or the like is added to this as necessary. and collect it as rolling oil.

That is, as shown in FIG. 2, the scum 25 generated on the surface toward the return section 14 of the coolant tank 13 is collected, for example, in a scum collection tank 18, and then collected in the piping 1.
9 and then supplied to the reproducing device 20.

This regenerator 20VC button removes iron and ash from the scum, separates fats and oils from water, and if necessary, adds and mixes an emulsifier etc. to obtain recovered rolling oil. , fats and oils can be forcibly floated using a centrifugal separation method, a pressurized flotation method, or the like.

Next, after regenerating the rolling oil as described above, the recycled recovered rolling oil is sent to the rolling oil storage tank 26 through the pipe 21.

If necessary, new rolling oil is supplied through the rolling oil storage tank 26Vc through the piping 22, and recovered rolling oil or a mixed oil of it and new rolling oil is supplied from the rolling oil storage tank 26 to the piping 11 via the pump 27. is sent to the mixing tank 16, where it is mixed with a low concentration emulsion to form a high concentration emulsion toner.

In addition to the above-mentioned methods, various methods such as a magnetic drum, a magnetic skimmer filter, and the like can be used to collect the scum in the tank 13.

As explained in detail above, the method of the present invention extracts a part of the low-concentration emulsion that is supplied as roll coolant to the exit side of each stand of a cold rolling mill, and adds new rolling oil to it to create a high-concentration emulsion. In addition to making it into an emulsion, when spraying it as a rolling lubricant before the biting of each stand,
Collect the scum generated in the low concentration emulsion,
While removing foreign substances such as iron and ash contained in this scum, oil and fat are separated from water, and if necessary, an emulsifier is added to the oil and fat to regenerate the recovered rolling oil. It is reused as part or all of the rolling oil that should be newly added.

Therefore, as shown in Figure 1, compared to the case where the oil and fat content is not recovered from the scum, it is possible to reduce the amount of recovered rolling oil that is recovered and recycled from the scum, and the rolling oil consumption rate is greatly reduced. can.

That is, the set concentration of the high concentration emulsion prepared in the mixing 16 is CH x 102%, the concentration of the low concentration emulsion supplied from the pipe 10 is C x 102%, the flow rate QM is medium, and the high concentration injected from the nozzle 4 is The flow rate of the emulsion is QH, the regeneration amount of recovered rolling oil is LRCl/, the replenishment amount of newly added rolling oil is LFt/H2, and the flow rate of the high concentration emulsion supplied to the mixing tank 16 through the pipe 11 is QL /, /H. Then, the formula holds true.

Therefore, the required new supply amount LF of rolling oil is L, =C
, -CQ□-job.

(4) -C 1>CH>C (41), and the amount of new rolling oil replenishment can be reduced by this regeneration amount LRCO.

By the way, 0, 21 rolled at a cold rolling rate of 90%
Using a stop material of 6mm thickness x 785mm width,
Rolling speed 15 to 0.151xm thickness with single stand mill
When rolling was carried out at 00 MPM and a working efficiency of 45 T/H, and at this time, rolling oil was supplied according to the method of the present invention as shown in FIG. 2, the results shown in Table 2 were obtained.

As a result, it can be seen that the amount of new rolling oil replenishment is reduced by 36 times.

In addition, at this time, if the amount of oil and fat recovered from the scum is further increased, the amount of new rolling oil replenishment can be further reduced.
The lubrication function can be improved by increasing H further.

As described above, in the method of the present invention, scum is separated from the low-temperature rolling oil emulsion liquid circulating as a roll coolant,
By effectively utilizing this scum, it becomes possible to further lower the temperature of the roll coolant and further enhance its cooling function, which is also advantageous for the surface quality and shape of the strip of rolled material.

[Brief explanation of drawings]

Figure 1 is a flow sheet showing a low concentration rolling oil emulsion circulation system and a high concentration rolling oil emulsion extraction system for the method of the present invention, and Figure 2 is a flow sheet showing an example of a scum recovery system. It is a sheet. Code 1...Stand, 2...Strip, 3...Piping, 4,5...Nozzle, 6.7...Pump , 8... Filter 9.10, 11.12... Piping, 13.
... Coolant tank, 14 ... Return section, 15 ... Sending section, 16 ... Mixing tank, 17 ... Agitator, 18 ... ...
...Scum collection tank, 19.21, 22.24...
...Piping, 20...Regenerator, 23...
...Mixing device, 25...Scum, 26.
...Rolling oil storage tank, 27...Pump.

Claims (1)

[Claims] 1. While circulating an emulsion of low-concentration and low-temperature compressed ffl oil as a roll coolant injected to the exit side of each stand of a cold rolling mill, the circulating emulsion f
To the oil extraction part extracted as part of J-: New rolling oil is added to make a highly concentrated emulsion liquid, and if necessary, it is heated and pressurized and used as a rolling lubricant before the biting of each stand. After spraying, the rolling oil emulsion liquid is mixed with the circulating emulsion liquid and has a low concentration and low temperature.The resulting scum is collected, and foreign substances such as iron and ash contained in this scum are removed. On the other hand, the fats and oils are separated from the water, and then this fats and oils, if necessary, are blended with an emulsifier, etc., and added as part or all of the new rolling oil to be added to the extraction section. A method for supplying rolling oil in a cold rolling mill characterized by the following.