JP2546032B2 - TFS vertical electroplating tank for welding cans - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a vertical electroplating tank for TFS for welding cans.

[Prior Art] Since the TFS (tin-free steel) film is formed by a lower layer of a metal chrome layer having a higher melting point than steel and an upper layer of a chrome hydrate oxide layer that is an insulating film, Welding is not possible. Therefore, various studies have been conducted to enable welding, and it is known that welding can be performed by depositing a metallic chromium layer in a granular form. In this case, in the intermittent electrolysis, the surface of the plate-like metallic chromium produced during the first electrolytic treatment changes to chromium oxide when the electrolysis interruption time is 0.3 seconds or more, and chromium oxide is the base of the re-electrolytic treatment. It has been reported that metallic chromium is preferentially precipitated in this portion during re-electrolysis treatment to become granular metallic chromium (metal surface treatment VOL 35, No. 8, P397 to 401, 1984).

[Problems to be Solved by the Invention] However, the manufacture of TFS generally uses a vertical electroplating tank. In this electroplating tank, even if one-pass electrolysis is performed, leakage current from the electrolytic path to the opposing steel plate is As a result, the electrolysis interruption time is difficult to obtain and the granular deposition of metallic chromium is difficult.

Therefore, in order to cut off the above leakage current,
A method of incorporating the shielding plate into the plating bath is adopted. This method has a structure in which an insulating plate in which an insulating material is lined on a vinyl chloride plate or an iron plate is arranged in the center of the plating tank, and the shielding plate is held by a support having upper and lower ends attached to the inner wall of the plating tank.

However, in this method, the shield plate width is 100 mm or more smaller than the plating bath inner width in order to facilitate loading and extraction of the shield plate into the layer for maintenance of the shield plate and inspection in the plating bath. It is usually designed.

Therefore, a gap of 50 mm or more is formed on one side between the shield plate and the inner wall of the plating tank, and a large amount of leakage current flows in through the gap, so that there is a problem in that metallic chromium cannot be deposited in granular form.

The present invention is intended to solve the above problems, and an object of the present invention is to provide a vertical electroplating tank for a TFS for a welding can, which can surely deposit metallic chromium particles.

[Means for Solving the Problems] In order to achieve the above object, the present invention comprises a steel sheet turning roll installed at the bottom of a tank and a pair of anodes for plating both surfaces of a steel sheet descending in the tank. Downward electrolytic path consisting of, an upward electrolytic path consisting of a pair of anodes for plating on both sides of a steel plate rising in the bath, and an electrolytic path installed detachably on the upper part of the direction changing roll, A shield plate is provided to block leakage of current from the energized electrolytic path to the non-energized electrolytic path, and the gap between the left and right ends of the shielding plate and the inner wall of the plating tank is hidden from both sides of the shielding plate. The auxiliary wall is a TFS vertical electroplating tank for welding cans, which is provided on the inner wall of the plating tank near the left and right ends of the shielding plate.

[Operation] Since the present invention has the above-described structure, when the TFS for a welding can is manufactured using the vertical electroplating tank of the present invention, the shielding plate and the auxiliary wall as described above are provided to make the electrolytic path Of these, the leakage current inflow rate from the energized electrolytic path to the non-energized electrolytic path can be sufficiently reduced, and electrolysis is interrupted to form granulated metal chromium on the steel sheet that passes through the non-energized electrolytic path side. Can be processed. As a result, it is possible to uniformly form a predetermined granular chromium metal on the TFS.

As will be described later, the leakage current inflow rate is controlled to be less than 0.1% in view of the relationship with the evaluation of the granularity of metallic chromium, so that the granularity (A) is obtained.

[Examples] Examples of the present invention will be described below with reference to the drawings.

1 (a) and 1 (b) are views showing an embodiment of the present invention, FIG. 1 (a) is a plan view, and FIG. 1 (b) is a side view. In the figure, 1 is a vertical electroplating bath, 2 is a shielding plate, and 3a and 3b are auxiliary walls. The vertical electroplating tank of the present invention is, as shown in FIG. 1 (a), a shield plate 2 arranged in the central portion of the vertical electroplating tank 1 and an auxiliary wall provided so as to sandwich the side surface of the shield plate 2.
It is configured by including 3a and 3b. In this case, the shielding plate 2 is arranged vertically in the center of the plating tank 1 and has a width narrower than the width of the plating tank that is normally used. That is, it is designed to be 100 mm or more smaller than the width of the plating tank. The auxiliary wall 3a and the auxiliary wall 3b are sandwiched so as to completely cover the gap between the inner wall 1a of the plating tank 1 and the end of the shield plate 2. The auxiliary wall 3a and the auxiliary wall 3b are the inner walls of the plating tank 1.
It is attached to 1a.

Further, as shown in FIG. 3B, the auxiliary wall 3a (3b) is arranged so as to cover the entire length of the shield plate 2 in the vertical direction. 5 is a direction change roll. The preferred positional relationship in this case is as follows.

Gap between shield plate and auxiliary wall ... 5 to 20 mm Length of overlapping part between shield plate and auxiliary wall ... 50 to 200 mm If the gap between the shield plate and auxiliary wall is too narrow, it is difficult to insert and extract the shield plate. However, if it is too wide, the effect of blocking the leakage current decreases.

If the length of the overlapping portion of the shielding plate and the auxiliary wall is too small, the effect of blocking the leakage current will be reduced, and if it is too large, the effect will not increase extremely and will hinder the maintenance and inspection in the plating tank. FIG. 2 is a diagram showing another embodiment of the present invention.

A shielding auxiliary plate 4 is provided on the extension of the shielding plate 2 in the width direction,
The width of the shield plate 2 is narrowed to make it easier to insert and extract the shield plate than the shield plate of FIG. The shielding auxiliary plate 4 is fixed to the inner wall 1a of the plating tank 1.

A method for manufacturing a TFS for a welding can using the vertical electroplating tank of the present invention will be described with reference to FIG. A plurality of vertical electroplating baths are arranged in series, and the vertical electroplating bath 1 of the present invention is used for at least one of the vertical electroplating baths. A vertical electroplating bath normally performs two-pass electrolysis.
The plated steel sheet 8 having the lower layer of the metal chromium layer and the upper layer of the chromium hydrated oxide layer formed in the above vertical electroplating tank is negatively charged, and the plating bath of the vertical electroplating tank 1 of the present invention is obtained. Delivered to 6a. Since the electrolysis is interrupted here, the direction is changed by the direction change roll 5 without being plated, and the electrolytic bath is electroplated between the anode 7 as the counter electrode in the plating bath 6b, and is withdrawn. , Transferred to the next vertical electroplating tank. In this way, each vertical electroplating tank obtains a predetermined amount of plating and is processed as a product.

FIG. 3 is a diagram showing an experimental result of the relationship between the position in the steel sheet width direction and the leakage current inflow rate according to the present invention. Here, using a conductive paper corresponding to the vertical electroplating bath of the present invention as shown in FIG. 1, the leakage current inflow rate (%) of the electrolysis current on the electrolysis side into the steel plate on the electroless side ( %).

The main conditions in this case are: the gap between the shielding plate and the auxiliary wall is 10 mm, and the length of the overlapping portion between the shielding plate and the auxiliary wall is 100 mm.
And It should be noted that the case where the other conditions were the same except for the auxiliary wall was taken as a comparative example, and the case where the shielding plate and the auxiliary wall were removed and the other conditions were made the same as the conventional example. Inventive examples are shown by a solid line, b is a comparative example by a dotted line, and c is a conventional example by a one-dot chain line. As is clear from FIG. 3, according to the present invention, the leakage current inflow rate is uniform and decreases uniformly in the width direction of the steel sheet as compared with the comparative example and the conventional example. . In comparison, the edge portion of the steel sheet has a high leakage current inflow rate. The conventional example not using the shielding plate shows a worse result than the case using the shielding plate.

Next, the above results are put on a real line, electrolysis is interrupted in the vertical electroplating tank of the present invention, and then a predetermined plating adhesion amount is obtained in each of the other vertical electroplating tanks and treated as a finished product. The granulation shown in the figure was evaluated. In the figure, the vertical axis A
Shows the case where the granular metal chromium is densely generated, B shows the case where the granular metal chromium is partially generated, and C shows the case where there is no granular metal chromium. In the examples of the present invention, A was obtained although all were plotted with ⊚. On the other hand, when a shielding plate was used, it was plotted with a circle, but it was ABC,
When the shielding plate is not used, it is plotted with a triangle, but B-
It was C.

[Effects of the Invention] When a TFS for a welding can is manufactured using the vertical electroplating tank of the present invention, the leakage current inflow rate can be sufficiently reduced during the electrolysis interruption time for forming the granular metal chromium. As a result, it is possible to uniformly form the predetermined granular metal chromium, and as a result, it is possible to stably manufacture the TFS for a welding can.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing another embodiment of the present invention, and FIG. 3 is a diagram showing the relationship between the width direction of the steel sheet according to the present invention and the leakage current inflow rate. The figure which shows the example of an experiment, 4th
The figure shows the evaluation of the leakage current inflow rate and the granularity of metallic chromium. 1 ... Vertical electroplating tank, 2 ... Shielding plate, 3a, 3b ... Auxiliary wall,
4 ... Shielding auxiliary plate.

Claims (1)

(57) [Claims] 1. A steel sheet turning roll installed at the bottom of a tank, a downward electrolytic path consisting of a pair of anodes for plating both surfaces of a steel sheet descending in the tank, and both sides of a steel sheet rising in the tank. Upward electrolytic path consisting of a pair of more than one anode to be plated, is installed in a detachable state on the upper part of the direction change roll, from the electrolytic path which is energized among the electrolytic paths to the electrolytic path which is not energized A shielding plate for shielding the leakage of the electric current, and an auxiliary wall for concealing the gap between the left and right ends of the shielding plate and the inner wall of the plating plate from the front and back sides of the shielding plate. TFS vertical electroplating tank for welding cans equipped on the inner wall.