JP2656629B2 - Apparatus for supplying lubricant for hot rolling stainless steel and method for preventing nozzle clogging in the apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for supplying a lubricant supplied to a roll to prevent seizure of the rolled material by the rolled material at the time of hot rolling of stainless steel, and an apparatus therefor. The present invention relates to a method for preventing nozzle clogging.

Conventional technology Rolling is conventionally performed by rolling the same steel type in order from the widest one to the narrowest one in order to prevent the surface of the product edge from being worn out by the abrasion of the rolling rolls, and to prevent the shape from becoming irregular. I was Therefore, in order to set a rolling schedule, it is necessary to arrange the same steel type and arrange them in order from wide to narrow, and there were schedule restrictions on the steel type and the size of the rolled material, In recent years, high chromium rolls with high wear resistance have been provided, and accordingly, schedule-free rolling, which is not restricted by steel type and size, such as rolling of different steel types and rolling with large and small sizes, has been adopted. Has begun to be.

However, in the case of stainless steel, the use of a high chrome roll has the following problems.

First, since the high chromium roll is a component system similar to stainless steel, seizure of stainless steel is likely to occur.

Second, unlike a normal steel, an oxide film is not formed on a roll, and since the scale of a rolled material is small, metal contact between the roll and stainless steel occurs, and linear roll flaws are likely to occur. This is especially true for ferritic single-phase stainless steel.

The use of lubricating oils has also been considered as a countermeasure to the above-mentioned problems. Lubricating oil is widely used in the rolling of ordinary steel because it has the effect of lowering the wear coefficient by being interposed between the rolling roll and the rolled material, and the same effect is expected even in the case of stainless steel, preventing seizure. However, when the rolling load is large, such as a work roll in the pre-finishing stage where the rolling load is large, the oil film is liable to be cut and metal touch occurs, and existing animal and vegetable oils and fats are used. Class and mineral and synthetic rolling oils were not sufficient.

Therefore, it is conceivable to supply an aqueous solution of iron oxide powder between the roll and stainless steel to prevent the metal touch between the roll and stainless steel and to prevent linear roll flaws, thereby giving the function of an oxide film. It has been proposed to use a highly viscous aqueous solution to uniformly disperse the iron oxide powder. Specifically, a viscous aqueous solution of a crosslinked acrylic acid polymer, carboxyvinyl polymer or the like (viscosity of 1 × 10 ^{3 to} 5
× 10 ⁴ cP) in which fine powder of iron oxide is dispersed in an amount of less than 30% by weight.

Problems to be Solved by the Invention It has been clarified that the above-mentioned lubricant can prevent roll flaws, but there are some problems to be solved in practical use even if an appropriate effect is obtained at an experimental level.

One of the obstacles to implementation is the lack of a suitable device for pumping high viscosity lubricants as described above and spraying them on the rolling rolls. Incidentally, the rolling oil supply device that has been conventionally used cannot pump the high-viscosity lubricant as described above.

If a plunger pump is used, a high pressure can be obtained, but pulsation occurs, so that the lubricant cannot be uniformly sprayed on the rolling rolls and seizure cannot be prevented.

A first object of the present invention is to provide a supply device capable of uniformly spraying a high-viscosity lubricant as described above, thereby removing one of the obstacles to practical use. .

The second obstacle to the implementation is that, when used for a long period of time, rust is generated in pipes and tanks, which causes nozzle clogging.

A second object of the present invention is to solve the above problem.

A third obstacle to implementation is that the lubricant adheres and solidifies to the nozzle, the inner wall of the pipe, and the thread groove of the pipe joint. In particular, it is conceivable that the lubricant is used only for stainless steel, which tends to cause metal touch due to high cost, and the conventional rolling oil is used for other steel types such as ordinary steel. Therefore, a non-use period occurs, during which the lubricant remaining in the pipe solidifies, and when reused, the solidified lubricant adhered to the pipe inner surface is likely to peel off, causing nozzle clogging.

When rolling oil is used, the solidification that causes nozzle clogging is due to the rolling oil component, so changing the rolling oil component such as polymers and fatty acids, preventing the production of iron soap by adding a chelating agent, and rolling oil viscosity Although measures to prevent nozzle clogging, such as a decrease in oil content, can be easily performed, the above-described preventive measures cannot be applied to oil-free lubricants obtained by dispersing iron oxide powder in a highly viscous aqueous solution.

Also, simple flushing with water, which is known as a method for cleaning pipes, cannot completely remove the lubricant due to high adhesion of the lubricant to the pipes, and nozzle clogging, which is considered to be caused by residual lubricant, is likely to occur.

A third object of the present invention is to improve a flushing method,
It is intended to completely remove the lubricant in the pipe after the use of the lubricant to prevent nozzle clogging due to residual lubricant.

Means for Solving the Problem and Action In order to achieve the first object, a high-pressure plunger pump is used, and an accumulator is provided on a pipe between the pump and the nozzle as means for preventing disturbance of an injection pattern due to pulsation.

Therefore, the first invention is to use iron oxide powder in a viscous aqueous solution.
A stainless steel hot rolling lubricant supply device for supplying a lubricant dispersed in an amount of less than 30% by weight between a rolling roll and a rolled material, comprising: a tank in which the lubricant is stored; It is characterized by comprising a high-pressure plunger pump to be connected, one or a plurality of nozzles directed to a rolling roll, and an accumulator installed on a pipe between the nozzle and the plunger pump.

According to the present invention, the high-pressure energy generated by the plunger pushing of the plunger pump is absorbed and stored by the accumulator in a considerable amount. On the other hand, when the plunger is retracted, the energy stored in the accumulator is released, whereby the lubricant is leveled and injected from the nozzle.

According to our experiments performed in this regard,
The pumping pressure and nozzle diameter have a great effect on the spray pattern of the lubricant sprayed from the nozzle, and in order to perform stable supply without fluctuation of the spray spread width, the viscosity using a crosslinked acrylic acid polymer as a thickener When a lubricant (5 × 10 ⁴ cP) containing 10% by weight of iron sesquioxide fine powder mixed in an aqueous solution is used, a pump pressure of 150 to 220 kgf / cm ^{2 is} required, and the nozzle diameter is 1.7 / flow rate. It was found that it was necessary to use a small-diameter nozzle that was smaller than min. That is, the major axis is 0.
Using a small-diameter nozzle with an oval shape of 56 mm and a minor axis of 0.2 mm and an enlarged nozzle with a nozzle diameter of 1.36 mm and a minor axis of 0.6 mm, the injection width and nozzle discharge pressure at a distance of 150 mm from the nozzle were measured. However, as shown in Table 1 below, in the enlarged nozzle, the discharge pressure is reduced to 0 to 70 kgf / cm ² and the ejection width is also 0 to 1 kgf / cm ^2.
In contrast to a large variation of 60 mm, it was recognized that the discharge pressure of the small-diameter nozzle was relatively high at 150 to 220 kgf / cm ² and the ejection width was stable at 210 mm.

The second invention is characterized in that the tank and the pipe in the lubricant supply device are formed of a rust preventive material such as stainless steel in order to prevent nozzle clogging due to generation of rust.

It is desirable to attach a strainer to the piping between the tank and the nozzle, especially the piping near the nozzle, to prevent foreign substances such as rust from entering.

According to a third aspect of the present invention, as a method of preventing nozzle clogging in the lubricant supply device, a pipe for supplying water and high-pressure steam is connected to a pipe to which the lubricant is supplied, and water is supplied to the lubricant pipe after use of the lubricant. Then, steam is sent in and flushing is performed.

In connection with the present invention, the present inventors further conducted the following experiments.

Install an offline test pipe as shown in Fig. 2,
The lubricant was run for 60 seconds. After that, the inside of the pipe was flushed with water and high-pressure steam. After leaving for one week, the pipe was cut and the inside was observed. These tests were performed on three types of lubricants having different viscosities. The results are shown in Table 2.

As can be seen from Table 2 above, even if the viscosity of the lubricant is high and the flushing with water alone shows a residue of the lubricant in the pipe, the flushing with the high-pressure steam will reduce the lubricant. It was found that it could be removed.

It was noted that the lubricant remaining in the pipe was solidified after flushing and left for one week.

First Embodiment FIG. 1 shows an apparatus for supplying a lubricant to a work roll 1. A high-pressure plunger pump 5, an accumulator 6, a strainer 7, and an ON pipe 4 are connected to a pipe 4 from a tank 2 in which the lubricant is stored to a nozzle 3. A -OFF valve 8 is installed in order, and the lubricant in the tank is pressure-fed by a plunger pump 5, is injected from the nozzle 3, and is supplied to the work roll 1. The nozzle is located closer to the nozzle than the ON-OFF valve 8. Is connected to a pipe 9 to which water or high-pressure steam is supplied. In the figure, 11 is an ON-OFF valve installed on the pipe 9, and 12 is a backup roll.

Effects of the Invention The present invention is configured as described above and has the following effects.

According to the supply device of the first aspect, it is possible to supply a high-viscosity lubricant in which iron oxide powder is dispersed to a rolling roll at an actual machine level.

By using the small-diameter nozzle with the pump pressure according to the second aspect, the injection width is constant and stable supply can be performed.

According to the supply device of the third aspect, clogging of the nozzle due to generation of rust can be eliminated.

In the supply device according to the fourth aspect, by providing the strainer, it is possible to prevent nozzle clogging due to entry of foreign matter.

According to the method of the fifth aspect, by performing flushing with water and then steam, the lubricant in the piping can be removed, and nozzle clogging can be eliminated.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a lubricant supply device according to the present invention, and FIG. 2 is a schematic diagram of an off-line flushing test pipe. 1 work roll, 2 tank, 3 nozzle, 4
... Piping, 5 ... High pressure plunger pump, 6 ... Accumulator, 7 ... Strainer, 8 ... ON-OFF valve, 9 ... Pipe

 ────────────────────────────────────────────────── ─── Continued on the front page (56) References JP 7-63732 (JP, B2) JP 7-112564 (JP, B2) JP 6-62980 (JP, B2) JP 7- 45056 (JP, B2)

Claims (5)

(57) [Claims] 1. A stainless steel hot rolling lubricant supply device for supplying a lubricant in which iron oxide powder is dispersed in a viscous aqueous solution in an amount of less than 30% by weight between a rolling roll and a rolled material. A tank in which lubricant is stored, a high-pressure plunger pump connected to the tank, one or more nozzles directed to the rolling roll, and a pipe installed between the nozzle and the plunger pump. The lubricant supply device described above, comprising an accumulator. 2. The lubricant supply device according to claim 1, wherein the pump pressure is 150 to 220 kgf / cm ² , and the nozzle is a small-diameter nozzle having a flow rate of 1.7 / min or less. 3. The lubricant supply device according to claim 1, wherein the tank and the pipe are made of stainless steel. 4. The lubricant supply device according to claim 1, wherein a strainer is provided in a pipe between the tank and the nozzle. 5. The supply device according to claim 1, wherein a pipe for supplying water and high-pressure steam is connected to a pipe for supplying the lubricant, and after the use of the lubricant, water and steam are supplied to the lubricant pipe. A method for preventing nozzle clogging, characterized by flushing.