DE1810428C3 - Process for the continuous electroplating of wire or strip material - Google Patents

Description

»5 auxiliary electrodes supplied by an auxiliary power supply are arranged in the vicinity of the selected areas and opposite the selected areas

For galvanic tinning of steel strips areas is kept cathodic. The voltage using the halogen-tin process is easily dropped through the auxiliary power supply, usually a horizontal system is used that hold ao as the voltage of the main power supply The first arrangement of the electroplating unit consists of not much higher Hegt

a row of plating cells while a This British patent does not disclose any similar row of cells in an overlying arrangement

neten layer is located and a second cell arrangement 1. a continuous galvanic Vendnnungs-

education. The steel belt is moved in a horizontal position aj using a cell from

held and held by the unit by means of pairs of rollers horizontal type,

guided which is located between the electroplating cells 2. the immersion of the shield in the bath condition. The underside of the strip is tinned in the first between the anode and the cathode contact arrangement.

output end of the first arrangement vertically and 30 3. the maintenance of a negative potential

changes in the second arrangement in which the an- on the shield is within the range of

whose side is tinned, its direction. During the 0.03 to 0.2 volts and

Operation when the belt moves through the cell 4. the use of an internal electrical

moves away, and especially at speeds in the circuit through which the shielding

Range between 304 and 608 m / min, it pumps so that 35 the cathode busbar is connected,

at electrolyte towards the output end, and the by the method according to the invention will be

Electrolyte builds up at the top of the contact- the technical difficulties solved with the

roller. Since the anodes of the cell were connected using the Kan- known tinning process,

extend out of the strip, it is open - as is the case with the well-known horizontal electroplating

Lich that the current from the ends of the anode is also undesirable that the roller ends

directly to the surfaces of the contact rollers flow electroplated that the rollers are tinned through

which can easily be cleaned by blasting over the edges of the tape

extend out, and tin the ends of the roller lose their cylindrical shape and be renewed

can. Very little or no tin must strike and that the direct electrical path between

down on the surface of the contact roller, the 45 see the anode and the cathode contact roller

directly in contact with the tape must be blocked.

The problem of tinning the contact roller The invention relates to a method for is of no importance when a new, steel continuous galvanic tin plating of wire or chrome plated roller in a commercial or strip material in a horizontal plant, the da plant is set up. The tin is characterized by peri- 50 that is near the Kaodic blasting with a suitable abrasion method contact roller and essentially parallel to it medium removed However, it is practically not possible to remove a metallic flat of the roller connected to the Kadas Zinn via a resistor without a proportion of metal from the upper method busbar. Arranged in a relatively short time and on one opposite the the surface of the roller is not a real cylinder 55 surface of the cathode contact roller by 0.03 to more. If this condition occurs, the potential is kept between 0.2 volts more negative, the contact roller and the tape no good contact Because the negative potential on the shield maintain. This leads to an increase in the sustained and to a slightly stronger one Voltage drop in areas with poor mechanical negative (more cathodic) value than the roller see contact and cease to be excessively strong, tin will preferentially deposit divorce at the roller. The rollers are detached from the shield, and a deposit attached to it The unit is removed periodically and on the cathode roller is prevented cylindrical shape ground and polished after meh- F i g. Fig. 1 shows a side sectional view of a more such operating cycle, the roller is built into the contract galvanic cell with built-in metal and a new roller is installed in the unit 65 lischer shielding;

It is obvious that the cost of the abstract F i g. Figure 2 shows a plan view of an industrial one

len of the rollers during operation, the working galvanic cell with built-in metallic

time to change the rollers, the loss of clutter;

3 1 4

Fig. 3 shows a plan view of a laboratory dem. Those skilled in the art are familiar with these factors

galvanic cell with arranged metallic ab- able to the correct negative voltage difference

shielding, and to be determined for the respective electroplating system. Some

FIG. 4 shows a side sectional view of a load of the factors mentioned are at a distance between

Bonn-like galvanic cell with built-in me- 5 the shield and the surface of the roller, im

taUic shielding. Degree of flow movement of the electrolyte

The construction and operation of a commercial between the shield and the surface of the roller, in

and industrial electroplating metals are shown in FIGS. 1 a change in the composition of the elec-

and 2 shown.

half of the metal strip 11 to be coated is arranged.

net, and the anodes 12 are essentially. The removal of the shield from the upper surface at a distance of about 32 to 38 mm from the surface of the roller 15 is not critical; however, it is off the assembly line. The metal belt 11, usually a steel one, desired the shielding as close to the upper belt, is to be arranged by roller pairs 13, 14 and 15, 16 in the surface of the roller, as this is held without disturbing the horizontal position. The electrolyte 17 is pumped into the cell by the mechanical rotary movement of the roller and is on a liquid, in order to keep the tin deposit on the shield as mirrored as possible slightly above the strip 11. The vertical position of the storage tank with an overflow of the electrolyte from the cell lower edge of the shield opposite that through drain lines 18 and 19 to a not shown band is also not critical, but a distance of 25 to 50 mm from the cathode wall Band is generally auszen 13 and 15 are reaching with a negative terminal one. Although the curvature of the shielding is not shown similar to the DC power source over the circumference of the roll, the shaped busbars are connected, while the formation of the shielding is a critical factor, since the positive terminal of the DC voltage source is connected to a flat shield which is correctly inserted the conductive anode supports 20 is connected. 25 cell is arranged, also :; Electroplating of the roller between the rubber-coated counter rollers is completely prevented
14 and 16 and the cathode rollers 13 and 15, the laboratory pressure shown in FIGS. 3 and 4 is maintained at a moderately high pressure around a galvanic cell to ensure good electrical contact between the cathodes - the removal of the shielding on the peel rollers and to determine the belt to achieve as much as possible 30 manure on the roller. Ensure the geometric low voltage drop. Arrangement was basically a cutout

The metallic shield 21 is uniquely similar to an industrial electroplating cell and is provided and extends the width of the cell stand from a section of an anode bed, a 10 parallel to the cathode roller 15.Although made of a belt section and one end of a contact roller, For practical reasons, a one-piece conductor shield 35 The anode 22, the tape 23 and a portion of a Its simulated contact roller 24 is in a vertical position, making it easier to install and operate like, the shield can be located on either side of the cell 25. The length of the anode 22 Wall of the electroplating cell up to approximately was about 266 mm. Since a deposition on the Position of the edge of the wire or roller to be coated only through the one closest to the roller Extend the band. In view of the changes 40 anode area is affected, it was not for notin the width of the strips to be coated is sufficiently manoeuvrable, an industrial anode with a a shield on each side, if this is up to a length of 1520 mm in the laboratory electroplating a location above the tape extending which see cell install. The distance between the minimum width of the electroplating tape of the anode 22 and the tape 23 became 32 mm is equivalent to. 45 set. The distance from the end of the anode

The connection of the shield with the cable compartment 26 to the roller gap and to the strip end 27 method busbar is in Figs. 1 and 2 was not 412 mm. The simulated roller 24 consisted of shown. It is carried out using a suitable resistance - a steel sheet, which, depending on the circumstances, which ensures that the shield is on the surface of a roller with a diameter of is at a sufficiently negative potential, was curved 50 254 mm; the rear surface of the an electrodeposition on the shield simulated roller was yerzu with a cover Achieve and see a deposit on the roller to get the deposit on the convex surface surface to prevent. Restrict the cathode collector of the roller.

Rail is usually located on a low- A side view of the electroplating cell is in

docile stronger negative potential than the surface 55 F i g. 4 shown. The steel belt 23, which on

of the roller is arranged with regard to the voltage drop in the bottom of the electroplating cell, had a

Commutator or in other systems that lead to the elec- Width of about 25.4 mm and a length of about

fresh connection of the busbar with the 685 mm. The anode 22 extends approximately

running roller can be used. 127 mm above the upper edge of the steel belt

For a halogen-tin bath like that in the U.S.- 60's. The cathode or simulated roller 24 extended

Patent specification 2407 579 (Schweikher) is also described 127 mm above the top of the belt.

is, it has been shown that a negative potential wel- The steel band end 27 was at 24 by means of several

ches in a range of about 0.03 to 0.20 volts connected to a good electrical

is more negative than the surface of the roller to ensure Australian contact of the strip. Circu-

suffices. It depends on a number of factors 65 lation tubes 28 and 29 for the electroplating bath

which negative potential is sufficient to generate a galva- from tube 28

niche deposition a «of the shielding, electrolyte circulation at high speed

and to prevent electroplating of the cathode roller between the anode and the tape and from

Tube 29 causes a against the surface of the contact roller

A steel net 31 with a mesh size of 4.7 mm and a wire diameter of 1.2 mm was used for most of the tests and was shaped to match the circumference of the contact roll 24 corresponded. The circumferential dimension of the simulated roller 24 from the belt end 27 to the side wall the cell was 101.6 mm. The circumferential dimension of the shield from the sidewall of the cell up to about the one shown in FIG. 3 position shown was 38 mm, with the edge of the shield was about 19 mm from the tape. The level of electrolyte 30 in the cell was on a Height of 152 mm, measured from the top of the tape, held. A number of attempts have been made made, the vertical distance of the shield from the upper edge of the tape 23 and the Removal of the shield from the surface of the roller. The network 31 was electric »o connected to the steel band end 27 or with the same via a copper wire conductor with very little Resistance shorted. The negative terminal of the rectifier was also directly connected connected to the tape. The current flow was continued for a plating time of 10 minutes for each of the GaI plating experiments held constant at 15 amps. After electroplating, the simulated roller and belt assembly was removed and checked for buildup of tin in the various fields examined The results of the experiments are in the Table shown.

table

Influence of the position of the shield on the

Electroplating properties at one

Potential difference of 0.075 volts

35

vertical
P nt ff »r Farewell Deposition Distance
tion cniiei- at
Bandent at the Separation from
Dn _{n <} 4 distance simulated mung- DdUU beyond roller roller the mm anode mm 0 mm none 38 25.4 242 none 38 50.8 254 none 38 76.2 254 Section 38 292 19-19 mm *) 0 none 19th 25.4 260 none 19th 50.8 254 none 19th 76.2 260 Section 19th 292 19-38 mm *)

45

55

*} Corresponds to an area on the roller 24 in the left ν kidney corner opposite the tape (see Fig. 4).

The results according to the table show that the position with respect to the distance from the roll surface and the distance from the edge of the tape is not critical is

In the experiments described, the shield was directly connected to the one supporting the roller 24 Band connected. The voltage drop in the commutator, which is used in industrial systems to bring the current from the cathode busbar to the roller, can be higher than Be 0.075 volts, especially if the brushes are badly worn. If the voltage drop between the cathode busbar and the roller surface is unusually high, the shield is in place at a more negative potential than that to prevent deposition on the Roller is required. Under these circumstances, the current flowing to the shield can be reduced and easily by adding a resistor in the circuit from the shield to the Cathode busbar can be adjusted.

In the various tests, a steel mesh was used as a building material for the shielding. Perforated shielding or a mesh-like material is preferred because this way the Solution can pass through the shield without difficulty and the flow behavior within the cell is not noticeably affected. This is important, especially at high belt speeds (456 to 608 m / min) as the electrolyte is near the ends of each cathode roller at the exit end the cell reverses its flow direction and returns to the inlet end of the cell

Further modifications consist of expanded metal surfaces, grilles and other constructions, which allow a free flow and circulation of the electrolyte, such as metal rods, Wires or harnesses that are used for cleaning and reintroduction continuously through the Tape can be pulled. Rigid structures for the shield are also used in such applications sufficient, in which free flow of the electrolyte is not an important factor, for example in systems that work with wire or strip material at a lower speed.

Further modifications of the invention provide for operation with a shield that differs from others Conductor metals such as tin, stainless steel, chrome plated steel, copper, brass and Because it is desirable to have the deposited metal made of other substances in addition to steel regaining the shield at periodic intervals and reusing the shield, may be the choice of preferred metals for building the shield of economy and depend on the ease with which the coated metal is removed from the surface of the shield.

The main advantage of operating with a conductive shield is that the deposition at the Rolling is avoided and the need for blasting is reduced to a minimum, so that the operating times are extended before the formation of a bipolar Galvanisienmgszostandes. It can happen that the shield is deposited on rollers, which this state of wear and tear not prevented, as the electrical data of the system are of a completely different type.

1 sheet of drawings

552

Claims (1)

Operating hours and the cost of new ones Claim: Rollers cause expensive maintenance costs. Numerous attempts to establish a direct elec- Process for the continuous galvanic Irish path between the anode and the cathode tinning of wire or strip material in a contact roller to block and thus tinning Horizontal system, characterized by this - to prevent the rollers in industrial systems, net that near the cathode contact roller were unsuccessful. It's impractical to duck and essentially parallel to its axis an electrical path with a permanently installed insulation to block the width of the tin to be tinned via a resistor on the cathode collector Rail connected metallic shielding io nenden strip is variable arranged and on one opposite the upper By the method and the device used surface of the cathode contact roller ura 0.03 to tang according to British patent specification 1 064434 0.2 volts more negative potential is held. the electroplating of selected areas of cathodic workpieces can be prevented by a