JPH0780772A - Surface treatment method of steel and its device - Google Patents

Abstract

PURPOSE:To realize an adequate surface treatment by using rotary elliptical bodies which consist of steel having a specific diameter as abrasive grains, in devices to carry out a phosphate chemical conversion treatment and a sodium stearate treatment after carrying out a descaling treatment of a steel material by feeding the abrasive grains in a high speed air jet. CONSTITUTION:A steel wire rod 1 to be a steel of rust removal object is wound back from a supply stand 2, and delivered to a descaling device 4 through a correcting machine 3 so as to remove the rust. The descaling device 4 has plural descaling nozzles 4a, and abrasive grains and a superhigh pressure water are fed from an abrasive grain feeding device 5 and a water jet generating pump 6 to the nozzles 4a respectively. In this case, abrasive grains formed of steel balls or steel elliptical bodies whose hardness is higher than that of the steel of rust removal object, and the typical diameter in the mean weight area of the abrasive grain group is made less than 150mum, are used as the abrasive grains. The steel wire rod 1 after the rust is removed passes through a preheating device 7, a phosphate chemical conversion treatment device 8, a washing device 9, a sodium stearate treatment device 10, and the like, and a metallic soap lubricating film is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for a steel material, in which abrasive grains are supplied to a high-speed jet of water jet to descale the steel material, and then phosphate chemical conversion treatment and subsequent sodium stearate treatment are carried out. And its device.

[0002]

2. Description of the Related Art A method for treating a steel material with a phosphate is as follows:
Widely used as a rust preventive treatment and lubricating film for parts processing. In particular, whether or not the surface of the material for cold forging wire or bar is lubricated has a significant influence not only on the wire drawing step but also on the life and product quality of the cold forging die in the next step.

[0003]

As the surface lubricating treatment, a combination of forming a phosphate film and then subjecting it to a reactive soap treatment such as sodium stearate has been carried out as a favorable combination. 4-59 as an example
Japanese Patent Publication No. 972 discloses an in-line processing method for a long material which is continuously moving prior to wire drawing.

However, in this in-line processing method, even if the concentration of the processing liquid is increased, it is necessary to limit the drawing speed or lengthen the processing apparatus when incorporating it in a normal drawing process. Even if a reaction accelerator such as titanium colloid is applied to make up for the problem, a sufficient effect cannot be obtained.

Moreover, there have been problems in terms of economical efficiency and workability such as an increase in the consumption of the treatment liquid due to the high concentration, frequent sludge treatment and use of an expensive reaction accelerator.

As a method for removing an oxide film on a steel material before the phosphate chemical conversion treatment, pickling has a good descaling property, and since a large number of fine irregularities are formed on the surface of the steel material, a dense and highly adherent phosphoric acid It is said that a salt film can be obtained and is generally widely used, but there is a problem in that it requires a long treatment time and is not suitable for in-line treatment, and from the viewpoint of preventing pollution such as waste acid treatment.

Further, the reverse bending method and the shot blasting method can be used in-line, but since the surface unevenness hardly occurs, it takes a long time to complete the reaction, and there is a problem in economical efficiency and adhesion.

Since the wet blasting method has a problem that abrasive grains are stuck into the surface of the steel material, it is rarely used as such a descaling method before surface treatment.

In view of the above problems, the present invention is a steel material for obtaining a high-quality surface-treated material in which fine surface irregularities are formed by projection of an ultra-high pressure water jet and an abrasive, and a surface condition suitable for phosphate chemical conversion treatment is obtained. A surface treatment method and apparatus therefor are provided.

[0010]

The method of the present invention is a method for surface treatment of a steel material, which comprises performing a phosphate chemical conversion treatment and subsequently a sodium stearate treatment after removing scales such as rust and an oxide film on the steel material. As the abrasive grains to be supplied to the high-speed jet in the air of the high-pressure water jet, the material is steel, the hardness of which is equal to or higher than that of the steel to be rusted, and the shape is spherical.
After descaling the steel material with abrasive grains having a spheroid or a smooth surface shape in which these are combined and having a typical diameter in the average weight region of the abrasive grain group of 150 μm or less, a phosphate conversion treatment and subsequent stearin treatment are performed. It is a surface treatment method for a steel material, characterized by performing sodium acid treatment.

Further, the apparatus of the present invention comprises a descaling apparatus for steel material for supplying abrasive grains to a high-speed jet of ultra-high pressure water jet, a phosphate chemical conversion treatment apparatus, a sodium stearate treatment apparatus and a wire drawing die. Is a surface treatment apparatus for a steel material.

[0012]

According to the present invention, instead of applying a reaction accelerator which has been applied in the prior art, abrasive grains are supplied to a high-speed jet stream in the air of an ultra-high pressure water jet, and the abrasive grains are continuously jetted onto a moving steel material. Descaling method and device
Not only is the oxide film on the steel surface completely removed at high speed, but numerous infinitesimal surface irregularities are formed to create a surface condition suitable for phosphate chemical conversion treatment, thereby promoting reaction, densifying the film, and high adhesion. It is possible to realize.

Further, it is based on the fact that the required amount of metallic soap film can be formed in an extremely short time by reacting sodium stearate on the dense and highly adherent phosphate film. .

According to the present invention, the impact force of the water jet exerts an effective action on descaling at the time of rust removal, and the abrasive grains are supplied into the high-speed jet in the air,
Abrasive grains effectively act on the oxide film having high adhesiveness to completely remove the oxide film in a short time.

When removing the rust by the abrasive grains, it is particularly necessary to use the abrasive grains so as to prevent the abrasive grain agent from piercing the surface of the steel to be rusted and to give the surface a desired unevenness (roughness). The granules have the following characteristics in terms of material, strength, shape, and particle size.

That is, as the abrasive grains used in the present invention, (1) the material of the abrasive grains is steel, and the hardness thereof is not less than the hardness of the rust-free steel material. (2) The shape of the abrasive particles is a sphere, a spheroid, or a smooth surface shape combining these. (3) The representative diameter of the abrasive particle group in the average weight range is 15
It is set to 0 μm or less.

First, the reason for limiting the above (1) will be explained. By making the abrasive grains of steel, it is possible to prevent foreign components from adhering and mixing into the rust-removed steel material, and to reduce the hardness of the abrasive grains to the rust-removed steel material. If the hardness is equal to or higher than the above, it is possible to prevent pulverization of the abrasive grain and prolong the life of the abrasive grain. It can be prevented.

Explaining the reason for the limitation of (2), the abrasive particles are formed into a spherical surface, a spheroid, or a smooth surface shape in which these are combined, so that the abrasive particles can be applied to the surface of the rust-free steel material. The ratio h / d of the indentation depth h of the abrasive grains to the diameter or the representative diameter d of the abrasive grains can be suppressed to 0.2 or less at which no residual sticking occurs. In this way, it is possible to prevent residual sticking, which cannot be prevented by emery or river sand, and complete descaling is possible.

Explaining the reason for limitation (3), if the diameter (size) of the abrasive grains is reduced while the collision speed is kept constant, the number of irregularities and the area ratio of the concave portions formed on the surface of the steel material after descaling will be described. By limiting the representative diameter in the average weight range of the abrasive particles group to 150 μm or less, the surface irregularities that can obtain good lubricity as good as pickling in terms of the recess area ratio and the amount of phosphate coating are formed. You can let me do it. The recessed area ratio described here is the ratio of the recessed portions to the projected portions on the surface of the steel material, and the ratio is calculated from an electron micrograph.

Here, the representative diameter in the average weight range means that the diameter d of the abrasive particle group is measured by using a particle size analyzer, and the entire distribution range of d is divided into a plurality of minute ranges. Let the median for each be d _M. Further, the number n of abrasive particles belonging to a minute range is measured, and the average weight outside 1 is calculated from this n and d _M previously determined using the following equation (1) Equation 1, and then the average weight is calculated. The d _{M in the} minute range to which the abrasive particles having is belongs is referred to as a representative diameter in the average weight range.

[0021]

[Equation 1]

[0022]

[Outer 1]

In the above formula (1), d _{M is} the median value for each minute range ρ is the abrasive particle density n _{i is the} number of abrasive particles in the i-th minute range m is the number of divisions of the minute range.

As a suitable abrasive grain used in the descaling method of this steel material, as a material most satisfying the above conditions (1) to (3), steel dust generated in the steelmaking process by converter refining (usually Most preferred is OG dust).

The OG dust is solidified by air cooling and heat treatment in the process of collecting droplets and molten steel fumes generated at the time of bubble burst on the surface of molten steel by a dust suction device.
By utilizing the surface tension effect before solidification, it can be molded into a sphere, a spheroid, or a smooth surface shape combining these. After the recovered OG dust is polished, washed and sieved, if the hardness is insufficient, it is further heat treated to produce abrasive grains.

The increase in the number of irregularities increases the number of phosphate crystals starting from this and enables the formation of a dense film in a short time. In addition, the increase in the area ratio of the recessed portion brings about the improvement of the adhesion due to the so-called anchor effect. Further, by reacting sodium stearate on the dense and highly adherent phosphate film as described above, a required amount of metallic soap film can be formed in a short time.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of a steel material descaling and sizing line by an ultra-high pressure water jet of an abrasive grain injection method.

In the figure, a steel wire 1 which is a rust-free steel material
Is rewound from the supply stand 2 and first the straightener 3
Then, wire drawing and strain removal are performed, and then descaling is performed by the descaling device 4.

The descaling device 4 is provided with a water jet and a descaling nozzle 4a for injecting abrasive grains, which are arranged at a predetermined interval in the traveling direction and the circumferential direction of the steel wire rod 1 which is inserted through the descaling device 4, respectively. Also, abrasive grains and ultra-high pressure water are supplied from the water jet generation pump 6 to the jet nozzle 4a, and the steel wire rod 1 is rusted. The abrasive grains collected at the bottom of the casing are returned to the abrasive grain supply device 5 again, separated and reused.

The steel wire rod 1 from which rust has been removed is subsequently preheated to about 80 to 100 ° C. by the steel material preheating device 7, and then the phosphate chemical conversion treatment device 8 performs zinc phosphate chemical conversion treatment on the surface, followed by washing. After washing with the device 9, zinc stearate is deposited on the zinc phosphate film by the sodium stearate treatment device 10 to form a necessary amount of metallic soap film.

Then, after purging with the air purging device 11,
It is dried by the drying device 12, sized to a predetermined diameter by the wire drawing die 13, and wound by the winding device 14. Thus, after removing the rust by the ultra-high pressure water jet and the abrasive grain injection, the phosphate chemical conversion treatment and the subsequent sodium stearate treatment can be performed to form a sufficient metal soap coating on the surface of the steel wire rod 1. Therefore, the wire drawing die 13 can smoothly perform the wire diameter reduction drawing.

Table 1 shows the results of comparing the amount of zinc phosphate deposited by subjecting the surface after rust prevention to the phosphate conversion treatment by each descaling method. According to these results, the ultrahigh pressure water jet method is shown. When the representative diameter in the average weight range was set to 150 μm or less, both the area ratio of the recessed portions on the surface of the steel material and the amount of zinc phosphate adhered were equal to or greater than those when descaling by pickling.

In this case, the water jet supply pressure is 2000 kg / cm ² , and the abrasive grain concentration is 60 to 65 wt.
%, Slurry supply rate is 2.5 liters / nozzle
The test was performed with 10 min and the number of nozzle sets.

Table 2 shows that after the conventional shot blasting method and the descaling according to the example of the present invention, the phosphate chemical conversion treatment and the sodium stearate treatment were subsequently performed to obtain zinc phosphate and zinc stearate. The results of comparing the adhered amounts of No. 1 and No. 2 are shown. According to these results, the results of all of the comparison items of the present invention were superior to those of the conventional example.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

As described above, according to the surface treatment method and the apparatus thereof of the present invention, a phosphate coating and a metallic soap coating which are equal to or more than those in the case of pickling,
It can be processed in a short time to obtain high-quality surface-treated material, and in-line application of descaling and sizing, which has been a problem in the past, can be applied. It is possible to improve productivity, save labor, and extend die life.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of the present invention and showing an example of a descaling and sizing line of a steel wire rod by a water jet of an abrasive grain jet system.

[Explanation of symbols]

 1 Steel wire rod which is rust-free steel material 2 Supply stand 3 Straightener 4 Descaling device 4a Descaling nozzle 5 Abrasive grain supply device 6 Water jet generation pump 7 Preheating device 8 Phosphate conversion treatment device 9 Cleaning device 10 Sodium stearate Processing device 11 Air purge device 12 Drying device 13 Wire drawing die 14 Winding device

Claims (2)

[Claims] 1. A method for surface treatment of a steel material, which comprises performing a phosphate chemical conversion treatment and subsequently a sodium stearate treatment after removing scales such as rust and an oxide film of the steel material, and supplying it to an aerial high-speed jet of an ultra-high pressure water jet. As the abrasive grains, the material is steel, the hardness of which is not less than that of the steel to be rusted, and the shape is a sphere, a spheroid, or a smooth surface shape combining these, and the average weight of the abrasive particles group. After descaling the steel material with abrasive grains having a typical diameter in the region of 150 μm or less, a phosphate chemical conversion treatment,
A surface treatment method for a steel material, which is characterized by subsequent treatment with sodium stearate. 2. A steel material descaling device for supplying abrasive grains to an ultra-high-speed water jet of an ultra-high pressure water jet, a phosphate chemical conversion treatment device, a sodium stearate treatment device and a wire drawing die are provided in a traveling direction of the steel product. A surface treatment apparatus for steel materials, which is characterized by being arranged in rows.