KR20040019737A - Method for controling the current of conduction reflow in the plating process - Google Patents

Abstract

PURPOSE: A method for controlling conduction reflow current in electroplating process is provided which suppresses fluctuation of target temperature and prevents excess or shortage of alloy quantity and surface defects generated in the target temperature fluctuating range by varying strip resistance, required heat capacity and input current. CONSTITUTION: In a control method for preventing temperature fluctuation in case that a welding part between adjacent coils having different material specifications passes through conductor rollers in reflow process of the continuous electroplating process, the method for controlling conduction reflow current in the electroplating process is characterized in that the conduction reflow current is controlled by judging a distance between welding points from an input side conductor roller according to welding point tracking and operating strip resistance, required heat capacity (Q) and input current (I) by the following numerical formula: Q=v·A(C1+C2·TAVG)·ΔT (watts), where v is line speed (m/min), TAVG is an average temperature between temperature at the front of the input side roller and target temperature, ΔT is temperature increment, C1 and C2 are coefficients, A is cross sectional area of strip, I is shown below, ρ is specific resistivity of strip, L is a distance between the input side roller and quenching tank, Abefore is a strip cross sectional area of preceding coil, and Aafter is a strip cross sectional area of following coil.

Description

TECHNICAL FOR CONTROLING THE CURRENT OF CONDUCTION REFLOW IN THE PLATING PROCESS}

The present invention relates to a current control method of energized reflow in an electroplating process, which is one of the plating processes of steel manufacturing, and more particularly, welding when the preceding coil and the following coil are transferred at an arbitrary speed in the electroplating process. By tracking the points, calculating the amount of heat required to raise the temperature of each coil, and then calculating the input current by calculating the resistance of the strip as a function of distance to fit the transition interval, the free reflow target temperature The present invention relates to a current control method of energized reflow in an electroplating process in which a current amount is changed to suppress variation.

In general, as shown in Figure 1, the material subjected to the electroplating process undergoes a reflow melting process to form an alloy layer and to improve weldability, corrosion resistance and gloss, etc. It is possible by heating the above melting point of tin in the form of energizing heating by flowing an electric current through the strip 3 between and, followed by rapid cooling.

Plating line of continuous process type processes the material of coil type, and it is possible to continuously process in the plating process by providing coils of various material standards. In the reflow process, the strips 3 are transferred to two energizing rollers 1 and 2 and a current is supplied to the energizing rollers 1 and 2, whereby the amount of current applied is the size of the material to be treated, It depends on the cross sectional area and feedrate

Usually, several tens of meters of strips 3 are placed between the energizing rollers 1 and 2, and when the coil cross-sectional area is changed, that is, the size of the preceding material and the following material is changed, the welding point of the leading material is placed between the two conducting rollers. In this case, there is a difficulty in controlling the current required for energizing heating.

An example of the coil-to-coil current control method by controlling the energization reflow in the prior art is shown in FIG. 3.

That is, the input calorie change (11) during the reflow control of the thick material-mold material coil and the input calorie change (12) during the reflow control of the metal material-mold material coil are shown. When the required calorie (Q _before ) of the leading coil (Q _before ) and the trailing coil (Q _after ) required to reach the target temperature (T ₀ ) between the rollers (2CDR), the control change point is discrete at 1CDR or 2CDR. In this case, a phenomenon in which the target temperature is not reached while the coil welding point passes between the energizing rollers 1 and 2 is caused, which causes problems such as poor surface quality or insufficient alloying amount.

As a method for compensating for this, there is a control method shown in FIG. 4, which tracks a welding point at the entry and exit rollers 1 and 2, and from the input current and a specific voltage applied to the strip 3. It is a method of continuously calculating the change in impedance of the strip and changing the current when the strip impedance exceeds a certain range within the interval as the coil change point to the current required for the following material. Alternatively, current shortage may occur, resulting in poor surface quality.

Therefore, it is necessary to suppress the fluctuation of the target temperature by accurately predicting the impedance in the transition section where the leading coil and the trailing coil coexist in the reflow process in the continuous process and the appropriate current input accordingly.

Therefore, in the present invention, when the preceding coil and the following coil are being conveyed at an arbitrary speed, the welding point is tracked, the amount of heat required to raise the temperature of each coil is calculated, and the resistance of the strip is matched to the transition period. The purpose of this invention is to provide an energized reflow current control method in an electroplating process in which the amount of current is changed to suppress fluctuations in the reflow target temperature even in the free knitting of the preceding and following coils by calculating the input current as a function of the distance. .

1 is a schematic diagram of a reflow facility which is the subject process of the present invention;

Figure 2 is a heating pattern of the distance from the rolling roll of the strip by the reflow facility that is the target process of the present invention;

Fig. 3 is a pattern diagram (1) showing an inter-coil current control method by controlling energization reflow in the prior art;

Fig. 4 is a pattern diagram (2) showing a coil-to-coil current control method by controlling energization reflow in the prior art;

5 is a graph illustrating a coil-to-coil reflow current control method according to the present invention.

♣ Explanation of symbols for main part of drawing ♣

1: Entry energizing roller 2: Exit energizing roller

11: Change of input calories during reflow control of thick material-mold revolving coil

12: Changes in input calories during reflow control of the museum material-recycle coil

Q _before : Leading material calories Q _after : Leading material calories

Q _x : Required heat at the current distance (x)

I _x : Input current at current distance (x)

T ₀ : Quick cooling tank inlet temperature

In order to achieve the above object, the present invention provides a control method for preventing temperature fluctuations when adjacent welds having different material specifications pass through an energizing roller in a reflowing process of a continuous electroplating process. A method for controlling energized reflow current in an electroplating process, comprising determining a distance of a welding point from a roller and calculating and controlling strip resistance, required heat amount (Q), and input current amount (I) by the following equation. do.

(watts)

v: line speed (mpm)

T _AVG : Average temperature between front side roller and target temperature

ΔT: elevated temperature,

C1, C2: coefficient

A: strip cross section

ρ: strip resistivity

L: Distance from the entry roller to the quench tank

A _before : Strip cross section of the preceding coil

A _after : Strip cross section of trailing coil

Hereinafter, with reference to the accompanying drawings an embodiment according to the technical idea of the reflow current control method in the plating process by the current amount change when changing the material for the present invention as follows.

The configuration of the reflow facility of the electro tin plating, which is the target process of the present invention, is generally shown in FIG. A muffle furnace (4) is provided between the entry and exit rollers (1) and the exit and exit rollers (2) to preserve the temperature of the strip, and has a quenching tank (5) to plate the tin. To be quenched in the molten state.

In the case of an energizing roller for supplying AC power, the choke core coils 6a and 6b are provided outside the energizing rollers 1 and 2 so as to concentrate current between the energizing rollers 1 and 2. do.

Introduced strip (3) is started to heat from the current-carrying roller (1) to ensure that the appropriate current is injected in accordance with the material information and strip feed rate to reach the target temperature (T0) just before the water in the quench tank (5), Input calculations can be obtained from the following required calorie equations:

(watts)

v: line speed (mpm)

T _AVG : Average temperature between the front side roller entrance temperature and the target temperature

ΔT: elevated temperature,

C1, C2: coefficient

A: strip cross section

For the same material, only the feed rate of the strip is a factor that changes the required calories and input power. If the size of the material changes, the required calories must be calculated variably. have.

That is, when the size of the preceding coil and the following coil is different, the electrical resistance by the strip 3 becomes non-uniform and varies linearly when the welding point, which is the connection between the coils, passes through the energizing rollers 1 and 2.

At this time, the welding point tracking calculates the position (x) of the welding point from the entry roller, and there is a welding point in the transition section from the required heat amount (Q _before ) for the preceding coil and the required heat amount (Q _after ) for the trailing coil. In this case, calculate the required heat quantity (Q _x ), and find the electrical resistance of the strip between the rollers and calculate the amount of current (I) to be input from the following equation.

ρ: strip resistivity

L: Distance from the entry roller to the quench tank

A _before : Strip cross section of the preceding coil

A _after : Strip cross section of trailing coil

The target temperature (T ₀ ) just before getting into the quenching tank (5) differs in material specifications by varying the current according to the fluctuating electrical resistance input to the reflow until the welding point completely passes between the energizing rollers. It can be kept constant even when adjacent coils cross the transition section

As described above, according to the present invention, the variation of the target temperature is suppressed by varying the strip resistance, the required heat amount and the input current amount by the welding point tracking when the welding part between adjacent coils having different cross-sectional areas passes between the energizing rollers. There is an effect that can prevent excessive or insufficient amount of alloy, and surface quality defects that can occur in this section.

Claims (1)

In a control method of preventing temperature fluctuations when adjacent welds having different material specifications pass through the energizing rollers (1, 2) in a reflow process of a continuous electroplating process, Electroplating, characterized in that the welding point distance from the entry energizing roller (1) according to the welding point tracking, and calculates and controls the strip resistance, required heat (Q) and input current (I) by the following equation. Method of controlling energized reflow current in the process. (watts) v: line speed (mpm) T _AVG : Average temperature between front side roller and target temperature ΔT: elevated temperature, C1, C2: coefficient A: strip cross section ρ: strip resistivity L: Distance from the entry roller to the quench tank A _before : Strip cross section of the preceding coil A _after : Strip cross section of trailing coil