JPH0127159B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel structure of a soluble anode for high-speed zinc electroplating, and in particular to packing zinc lumps into a mesh box curved along a drum. Therefore, it is characterized in that it constitutes a soluble anode.

It is well known that galvanized steel sheets coated with zinc are used in a variety of applications.
Galvanized steel sheets are widely used in applications that require corrosion resistance, such as building materials and plants, and have recently become widespread as single-sided galvanized steel sheets for automobiles. Single-sided galvanized steel sheets for automobiles are required to have a zinc coating of 50 to 100 g/ ^m2 , and many efforts have been made to establish high line speeds of 100 to 200 m/min for such thick plating. ing. Furthermore, efforts are being made to save labor and automate the electroplating process.

Various proposals have been made to improve the zinc electroplating process, such as automating the steel sheet conveyance method, energization method, and electrolyte management, one of which is the use of soluble zinc anodes. . Conventionally, insoluble anodes made of lead have been used, but since the working power consumption is high, there is a tendency for soluble anodes to be used for energy saving purposes. Soluble zinc anodes are currently cast in the form of true plates or rods, suspended or supported by some means against a steel plate overlaid in an electrolyte.

Soluble zinc electrodes exhibit rapid wear from their tips or corners during electroplating operations. The square tip becomes tapered during use, resulting in poor plating finish and poor yield. Such tapering of the soluble zinc electrode cannot be avoided at present, and because of its thickness, this tendency becomes more pronounced as the limiting current density is increased. As mentioned above, thicker single-sided plated steel sheets have recently been used for automobiles, and there is a need to address the problem of electrode tapering.

The present invention addresses the problem of corner wear in soluble zinc electrodes used in high speed zinc electroplating methods in which the material to be plated is conveyed along the periphery of a drum in an electrolytic solution. The purpose of this invention is to provide a novel soluble anode structure.

In summary, the present invention provides a soluble anode structure for use in high speed zinc electroplating processes in which the plated material is transported along the circumference of a drum in an electrolyte, the structure being is curved with a curvature and has a curved length less than 1/4 of the drum circumference,
A soluble anode structure is provided which includes a mesh box with an open upper end and a ball-shaped zinc lump filled inside the mesh box.

During use of the electrode, as the zinc mass is depleted, subsequent zinc mass is displaced to compensate for the depletion, and the mesh box is automatically maintained at a substantially constant metal filling state. When the depleted zinc mass becomes smaller than the mesh of the box, it falls out. In order to prevent fallen zinc lumps from falling into the electrolyte, the present invention also provides, in addition to the above elements, a bag for enclosing the mesh box body in order to store metal lump pieces that have fallen off from the mesh box body. A soluble anode structure further comprising:

Referring now to the drawings, a plated material 1, such as a sheet of steel, is transported through an electrolyte along the circumference of a drum 2. The steel plate sheet is connected to the (-) pole side via the drum 2 or via another energized roll. A soluble anode structure 3 is arranged facing the material to be plated on the exit side where the material to be plated 1 is sent out from the electrolytic solution. The soluble anode structure 3 is curved with the same curvature as the drum 2, and maintains a constant distance from the plated material 1.

According to the present invention, the soluble anode structure 3 is composed of a mesh box 4 and a zinc lump 5 filled inside the mesh box 4. The mesh box body 4 is produced by braiding wire rods such as titanium into a wide box shape curved to match the curvature of the drum. Its upper end is open for charging the zinc ingot 5. The size of the mesh is appropriate to hold the undepleted zinc lump inside, and is generally 2 to 5 mm square. The shape of the zinc lump is preferably a shape that provides a larger surface area, such as a ball shape. For example, zinc lump 5
The balls are cast to a size of 10 to 100 mmφ, and are filled completely inside the mesh box body 4. The smaller the ball size, the higher the packing density, but the mesh of the box must be made thinner. Conversely, if the ball diameter is large, the mesh can be large, but the packing density is reduced.

During high speed zinc electroplating operations using the soluble anode structure of the present invention, the anode is depleted. In the case of a conventional solid plate-like structure, if tapering occurred, the entire electrode had to be replaced, but in the ball-filled structure of the present invention, as the balls wear out, subsequent balls successively lose gravity. Since it is displaced at the bottom to make up for the depleted portion, a substantially constant filling state is automatically maintained at all times. It is only necessary to replenish new balls from the open end of the box body in response to lost balls.

As the ball wears down and becomes small enough to pass through the mesh, the ball falls out of the mesh box. In order to prevent the fallen balls from falling into the electrolytic cell and affecting the electrolyte zinc concentration, it is preferable to provide means for collecting the fallen balls. The means for collecting the fallen balls may be a suitable receptacle placed under the anode structure, but one preferred embodiment is an acid-resistant material such as fine-mesh muslin as shown at 6 in FIG. It has been found that it is best to wrap the cloth bag in a mesh box.

Inside the mesh box, the zinc balls roll toward the front end to maintain contact with the adjacent ones as the balls wear out at the tip or fall off from the box. It is preferable to fill the balls as regularly as possible so that such displacement of the balls occurs smoothly. A partition may be provided as appropriate to maintain the arrangement of the balls inside the box.
By providing a partition that partitions the inside of each layer of balls, the balls can be arranged in an orderly manner. Furthermore, it is beneficial to use balls of different diameters to increase the packing density of the balls. The filling of the balls can be scaled by selecting the diameter and arrangement so that the smaller diameter balls occupy the spaces between the larger diameter balls.

As shown in the drawings, the soluble anode structures of the present invention are installed in pairs at the inlet and outlet portions of the drum, each curved with the same curvature as the drum and 1/4 of the circumference of the drum. Along the central bottom of the drum, the soluble anode structure does not extend, creating an intermittent space. This is because if the mesh box is too long, there will be parts that are close to horizontal and the automatic filling action under gravity will not work properly.If the mesh box is too long, the zinc mass will be filled before reaching the end. There is a risk that the electrolyte will be exhausted, making it impossible to ensure an appropriate filling condition at the terminal end, that the exhausted zinc lumps will easily fall off the mesh box, and that the circulation of the electrolyte will be improved. Depends on the reason.

The zinc electroplating operation itself using the soluble anode structure of the present invention is no different from the conventional method in terms of conditions. Depending on the width of the material to be plated, a plurality of anode structures may be arranged in parallel in the transverse direction.
In the case of thick plating, a similar anode structure, shown as 3' in FIG. 1, is installed on the inlet side where the material to be plated enters the electrolyte. The spacing between the plated material and the anode structure, current density, electrolyte composition and temperature are interdependent to establish the plating operating conditions, depending on the desired plating thickness and line speed. In galvanizing using the soluble anode structure of the present invention, thick plating is performed using a zinc sulfate bath (PH = 1 to 3) with a high zinc concentration of up to 500 g/min at a high line speed of about 200 m/min. was made possible.

The zinc balls can be replenished without interfering with the continuous plating operation by keeping the open upper end of the mesh box in communication with the hopper in which the spare balls are accumulated.

As explained above, the present invention solves the problem of tapering that has been found in conventional soluble anodes by providing a novel soluble anode structure for high-speed zinc electroplating in which a mesh box is filled with zinc lumps. This makes it possible to achieve sufficient uniform electrodeposition even under high-speed thick plating operations, and it is also easier to cast zinc ingots than a single solid anode body. This makes it possible to reduce manufacturing costs, and because there is no need to replace electrodes just by replenishing zinc ingots, it is possible to significantly reduce operating costs.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a plating situation using the anode structure of the present invention, and FIG. 2 is a perspective view of the anode structure of the present invention. 1: Plating material, 2: Drum, 3: Anode structure, 4: Mesh box, 5: Zinc lump, 6: Bag.

Claims (1)

[Claims] 1. A soluble anode structure used in a high-speed zinc electroplating process in which a plated material is transported along the circumference of a drum in an electrolytic solution, the structure having the same curvature as the drum. Curved with a curvature and 1/ of the drum circumference
1. A soluble anode structure comprising a mesh box having a curved length of less than 4 cm and having an open top end, and a ball-shaped zinc lump filled inside the mesh box. 2. A soluble anode structure used in a high-speed zinc electroplating process in which the material to be plated is transported along the circumference of a drum in an electrolytic solution, the structure being curved with the same curvature as that of the drum and 1/ of drum circumference
A mesh box having a curved length of less than 40 cm and having an open top end, a ball-shaped zinc lump filled inside the mesh box, and a zinc lump falling off from the mesh box. and a bag enclosing the mesh box for storing the pieces.