JP2000212765A - Method for controlling quantity of phosphate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the quantity of deposition of a phosphate film on a surface even when the phosphate treatment condition is specified by implementing the electrolytic picking in a pre-process of the phosphate film processing of a structural steel after the hot rolling and annealing, and controlling the density of the current running in the structural steel. SOLUTION: An annealed structural steel after the hot rolling is pickled and de-scaled, and subjected to the phosphate film processing and the lubrication film processing to improve the lubrication effect, and drawn and subjected to the plastic forming such as rolling. In a pre-process of the phosphate film processing, a strand-like structural steel 10 is immersed in a pickling solution 13 stored in a pickling solution tank 12 of an electrolytic pickling device, and a pair of upper and lower insoluble electrodes 11, 11 are arranged opposite to each other across the structural steel. The electrodes 11, 11 are energized to remove scales deposited on the surface of the structural steel 10. The quantity of deposition of the phosphate film can be instantaneously changed with excellent accuracy an unified without changing the phosphate film processing condition by controlling the density of the current running in the structural steel 10 to uniform the thickness of the phosphate film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the amount of a phosphate film, and more particularly to a method for controlling the amount of a phosphate film formed on the surface of a steel bar subjected to plastic working such as drawing or forging. On how to do it.

[0002]

2. Description of the Related Art Strips subjected to plastic working such as drawing are subjected to annealing after hot rolling, pickling for descaling, and phosphorus for improving the lubricating effect at the time of plastic working. It is manufactured through the respective steps of an acid salt film treatment and a lubricating film treatment.

That is, as shown in FIG. 3, after a raw material is formed into a coiled bar 1 by hot rolling, it is subjected to an annealing treatment, which is suspended by a carrier hook 2.
In the pickling treatment, the carrier hook 2 is lowered and the coiled bar 1 is immersed in the acid solution 4 in the acid treatment tank 3, and after the descaling is completed, the coiled bar 1 is moved into the acid solution 4. Pull up from inside.

Thereafter, in the phosphate coating treatment, the descaled coiled strip steel 1A is immersed in a phosphate coating treatment solution 6 in a treatment tank 5 for a predetermined time to apply a phosphate coating on the surface of the strip steel. After forming, withdraw. Then, a lubricating film is formed on the surface of the steel bar by the lubricating film treatment to obtain a steel bar to be subjected to plastic working such as drawing.

Here, it is necessary to change the adhesion amount of the phosphate film depending on the degree of plastic working of the bar steel. In addition, in order to prevent the forging die from being clogged by the phosphate film falling off at the time of cold forging, the bar steel is coated. In some cases, it is necessary to perform an operation for minimizing the amount of the phosphate film to be adhered.

However, the amount of the phosphate film deposited varies depending on the conditions of the coating solution (components, concentration, temperature, immersion time). Therefore, conventionally, the phosphate film treatment liquid which was in accordance with the conditions for each material to be treated was adjusted individually, and the solution which met the processing conditions was selected from the plurality of adjusted solutions, so that the amount of the phosphate film adhered was determined. Had control.

[0007]

However, it takes a considerable amount of time to prepare the processing solution by changing the conditions, and it is inefficient to change the solution conditions for each material to be processed. It is uneconomical to hold a plurality of processing liquids (processing tanks) in terms of occupied space, maintenance and management, and the like.

[0008] Further, even if the conditions of the phosphate coating solution are controlled with high precision, or even if a plurality of tanks are prepared, the batch system in the coil state as described above is generally used. In the pickling treatment, the descaling state cannot be said to be uniform over the entire length of the bar steel, and the amount of the phosphate film deposited due to the non-uniform descaling state often fluctuates.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is an electrolytic pickling process which is a pre-process of a phosphate film process. The purpose of this method is to provide a method that can freely increase or decrease the amount of the coating even when the phosphate coating treatment conditions are constant. A phosphate coating characterized by subjecting the strip steel to electrolytic pickling treatment and controlling the amount of the phosphate coating deposited on the surface by controlling the current density flowing through the strip steel during the electrolytic pickling treatment. The present invention provides a method for controlling the amount and a method for controlling the amount of phosphate coating adhered, wherein the steel strip is formed into a strand when the electrolytic pickling treatment is performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to an embodiment shown in FIG. 1. In the drawing, reference numeral 10 denotes a strand-shaped strip, which is formed by hot rolling a material by a conventional method. After molding, an annealing treatment is performed.

Numerals 11 and 11 denote a pair of upper and lower insoluble electrodes which are provided in an acid solution tank 12 in an acid solution 13 and sandwich the strand-shaped strip steel 10 fed into the acid solution 13. They are installed at positions facing each other. Then, in the electrolytic pickling apparatus having such a configuration, a scale is removed from the surface of the strand-shaped steel bar 10 by passing a current between the insoluble electrodes 11 and 11.

Here, the current density of the current flowing between the two electrodes 11, 11, that is, the current I (A) flowing between the two electrodes 11, 11 is determined by the effective area S (dm ² ) of the steel bar (dot in FIG. Marked part: the value obtained by dividing the distance between the steel bar 10 and the insoluble electrodes 11 and 11 by the shortest distance from the two electrodes 11) and the value of the phosphate film adhered by the subsequent phosphate film treatment. The quantity has a relationship as shown in FIG. Therefore, in the electrolytic pickling apparatus, a current flowing between the insoluble electrodes 11 and 11 has a current density that meets a condition of a phosphate film amount required for a material to be processed.

Next, the strand steel strip 10 having been pickled by the electrolytic pickling apparatus described above is immersed in a phosphate coating solution for a predetermined time in the same manner as in the prior art. This is completed by forming a predetermined amount of phosphate film on the surface and finally performing a lubrication film treatment.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS High carbon chromium bearing steel (SUJ2) with a diameter of 1.
It is processed into a 55 mm long bar, formed into a strand, and then fed into an acid bath of an electrolytic pickling apparatus to be subjected to electrolytic pickling with 15% hydrochloric acid. At this time, the current density is set to 300 to 4
It was changed to 100 A / dm ² . Then, a strand-shaped steel bar subjected to electrolytic pickling at each current density shown in FIG.
It was immersed in a phosphate coating solution (Palbond 3692X, manufactured by Nippon Parker Rising Co., Ltd.) at 0 ° C. for 60 seconds to form a phosphate coating.

The amount of the phosphate film adhered to the surface of the steel strip by the phosphate film treatment is as shown in FIG. 2, and even if the condition of the phosphate film treatment solution is constant, the amount of the electrolytic acid It has been clarified that the amount of the formed phosphate film can be increased or decreased by controlling the current density during washing.

[0016]

As described above, the method for controlling the amount of phosphate coating according to the present invention is to perform electrolytic pickling on a steel strip in a step before the phosphate coating treatment, Since the configuration is such that the amount of the phosphate film adhered to the surface thereof is controlled by controlling the current density flowing through the strip steel, without changing the conditions of the phosphate film treatment solution,
It is possible to instantaneously and accurately change the amount of the phosphate film adhered to the bar steel. Also, by adopting a configuration in which the strand steel in a strand shape is subjected to electrolytic pickling treatment,
There are various effects such that a phosphate film can be uniformly attached over the entire length, and a high quality product can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the operation of an electrolytic pickling apparatus used in the method of the present invention.

FIG. 2 is a diagram showing a relationship between a current density and a phosphate film amount.

FIG. 3 is an explanatory view of a conventional pickling treatment and a phosphate coating treatment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Strand-shaped steel bar 11 Insoluble electrode 12 Acid bath 13 Phosphate coating solution

Claims (2)

[Claims] In a process prior to a phosphate film treatment, an electrolytic pickling treatment is applied to a steel bar, and a phosphate adhering to the surface of the steel bar is controlled by controlling a current density flowing through the steel bar during the electrolytic pickling treatment. A method for controlling the amount of a phosphate film, characterized by controlling the amount of the film attached. 2. The method according to claim 1, wherein an electrolytic pickling treatment is performed on the strand steel in a strand shape.