JPS6125799B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrolytic treatment method, particularly an electroplating method, in which a metal is coated on the surface of a workpiece using an electrolytic solution in a treatment chamber maintained at low pressure, and a method used to carry out the method. It is related to the device.

Conventionally known electrolytic treatments have various technical and environmental disadvantages. The above-mentioned technical drawbacks include non-uniform electrodeposited coating thickness, slow coating formation, low coating density and poor coating adhesion. The above drawbacks are just a list of some of the most prominent drawbacks, and the biggest problem is that the coating is irregularly formed and thick in some areas.

The most important problem with respect to the prevention of defects in known treatment methods from the point of view of environmental security and safe operation is associated with the intense generation of gases and toxic fumes. However, these substances are toxic to the human body and often cause occupational diseases.

The object of the present invention is to provide a highly effective treatment method which avoids most of the drawbacks caused by the known methods.

Thorough testing of the process according to the invention, which is based on electrolytic coating under low pressure, has shown that it has a number of unexpected advantages. This means that the properties of the electrodeposited coating are greatly improved, and the toxic fumes normally generated during processing are already mixed and solidified in the circulating electrolyte at a low pressure of only 0.85 atm. The amount of toxic smoke generated depends on the electrolyte used and the current density. In order to ensure greater safety during the work, it is preferable to carry out the process under low pressure maintained at a pressure of 0.8 atm or less.

The most advantageous treatment method is to provide a suitable treatment chamber which is maintained at low pressure and to arrange for the electrolyte solution to be circulated through the treatment chamber. A circulation system with suitable cooling and heating mechanisms can therefore be used. Furthermore, it is possible to use devices in which no liquid circulates, but which is provided with an electrolyte reservoir that serves as a processing chamber.

In order to further simplify the treatment method according to the invention and the equipment used to carry out the method, it is possible to form a treatment chamber by arranging a container open at one end in an inverted position, with the opening opening opening for the electrolyte solution. If a low pressure source is connected to the electrolyte tank so as to be located below the liquid level in the tank, the low pressure electrolyte tank in an upright position will be filled with electrolyte solution up to the desired liquid level. According to this method, the conventional processing apparatus can be easily used in the processing method of the present invention by only slightly modifying its structure. A conventional electrolyte reservoir can serve as an electrolyte reservoir.

As mentioned above, it is not necessary to make the inside of the processing chamber itself the lowest pressure possible. That is, it is important to circulate the electrolytic solution while lowering the internal pressure within the processing chamber. This action achieves one of the greatest advantages in preventing the generation of toxic smoke and noxious gases. The effect of pressure reduction by electrochemical methods is itself less effective as the degree of pressure drop is smaller, but in most cases, ordinary materials are sufficiently effective for coating operations.

The treatment method according to the present invention can also be applied to the above-mentioned operations, and the environmental advantage of the present invention is that it can be used at low cost and with the addition of extremely simple equipment.

Good results can be obtained by setting the pressure difference such that the difference between the free liquid level of the electrolyte tank and the highest position in the low pressure system is approximately 1.5 m. The highest point of the low pressure system may be located outside the processing chamber. When the electrolytic solution flows and circulates through the processing chamber and a low-pressure circulation mechanism communicating with the processing chamber, if an air spring is installed at the upper end of the processing chamber, the processing chamber casing can be placed in a place where it does not come into contact with the electrolytic solution. The required power supply cable can be drawn in through the This operation can be easily performed by using packing when pulling in the cable.

The apparatus for implementing the treatment method according to the present invention includes an electrolytic solution tank, a low-pressure chamber, and a dam mechanism that circulates and flows the electrolytic solution flowing into the processing chamber from the electrolytic solution tank so that it returns to the electrolytic solution tank. There is. The above-mentioned damming mechanism is of the known type, operating on the same principle as the so-called releaser used, for example, in milking machines. From the electrolyte tank, the electrolyte flows directly into the low-pressure chamber under the influence of the low pressure in the low-pressure chamber, but a suction pump can also be used.

In the electrolytic treatment method, the electrolyte is heated, so it usually needs to be cooled. In the treatment method according to the present invention, for example, a heat exchanger is disposed between the treatment chamber and the damming mechanism to perform cooling treatment, and the heat exchanger is connected to the electrolyte circulation mechanism and the cooling mechanism. Each is connected. Ultimately, the cooling process must also be performed within the electrolyte bath, and in some cases, heating may also be required. A suitable temperature regulator is provided in the electrolyte bath to maintain the desired temperature. It is very convenient if the temperature regulator described above is connected to an electrolyte cooling mechanism used as a heat exchanger within the electrolyte circulation mechanism.

It is very advantageous in terms of processing that the processing apparatus according to the present invention is provided with a plurality of low pressure chambers having different volumes for electroplating workpieces of various sizes. The circulation mechanism is configured so that various low pressure chambers can be used simultaneously or selectively.

The details of the apparatus used in the processing method of the present invention will be explained with reference to the illustrated embodiment.

In FIG. 1, reference numeral 1 indicates an electrolytic solution tank, 2 indicates a small processing chamber, and 3 indicates a large processing chamber. The electrolytic solution tank 1 communicates with the small processing chamber 2 via the connecting pipe 4, and the electrolytic solution flows through the connecting pipe 4 from the electrolytic solution tank 1 into the small processing chamber 2 by suction, and further through the conduit 5 and the small processing chamber 2. The circulating electrolyte flows into a heat exchanger 7 via a three-way valve 6, and is cooled by the heat exchanger 7 as required. The electrolytic solution further flows from the heat exchanger 7 into the upper chamber 9 of the dam mechanism 8 . Since the vacuum pump 10 is connected to the upper chamber 9 of the damming mechanism 8, the electrolyte is still maintained at a low pressure. The circulating electrolyte is passed through a back stroke valve from the upper chamber 9.
If the pressure in the lower chamber 13 of the damming mechanism 8 is maintained at a low pressure, the water flows back through the lower chamber 13 of the damming mechanism 8 through the valve) 11 and the conduit 12. After the lower chamber 13 is filled with the electrolyte until it reaches a certain level, the damming mechanism 8 automatically cuts off the communication between the lower chamber 13 and the vacuum pump 10, and communicates the lower chamber with the atmosphere. action takes place. Therefore, the electrolyte flows into the electrolyte tank 1 through the conduit 1 under its own weight.

The electrolyte also flows by suction into the large processing chamber 3 via the connecting pipe 16, and further into the heat exchanger 7 and the dam mechanism 8 via the conduit 17 and the three-way valve 6. The desired circulation flow of the electrolyte can be achieved by adjusting the three-way valve 6. This three-way valve 6 is configured to allow circulation through the small and large processing chambers at the same time.

The device shown in FIG. 1 is a closed circuit 18 for liquid cooling.
The circuit 18 is equipped with an expansion chamber 19, a cooler 21 operated by an electric fan 20, a circulation pump 22 and the necessary equipment, such as a closing valve 23 and a reversing valve 24, respectively. The cooling water circulates through the heat exchanger 7 and flows around or inside the electrolyte bath as required. For example, sometimes in the early stages of the coating process a heat treatment is necessary if the temperature of the electrolyte is too low. The electrolyte bath is equipped with an electric heating device 25 to heat the electrolyte.

In practice, the coating process is carried out in the process chamber 2 or 3 by supplying power, usually from outside, via power cables 26 and 27 for activating the electric heating device. This coating treatment method is generally carried out in accordance with a known electroplating method.

In FIG. 2, a processing chamber 2 whose lower end is open is submerged within an electrolyte tank 1. Since the processing chamber 2 is connected to the vacuum pump 10, the electrolytic solution 34 in the electrolytic solution tank 1 rises to a desired level within the processing chamber 1. The electrolytic solution flows from the processing chamber 2 through the conduit 5 into the damming mechanism 8, and further flows back into the electrolytic solution tank 1 through the return conduit 15 for circulation. FIG. 2 further shows power cables 26, 27, their lead-in packings 40, and electrodes 41, respectively. The air spring 43 is formed below the lead-in cable packing 40 and serves to prevent the packing 40 of the processing chamber 2 from coming into direct contact with the electrolyte.

The processing device shown in FIG. 3 corresponds to the processing device shown in FIG. A washing fluid container 45 is provided, and the container 45 is connected to the electrolyte circulation mechanism in place of the electrolyte tank 1 by three-way valves 46 and 47. When the electrolyte tank 1 is cut off from the circulation mechanism and connected to the circulation mechanism of the washing fluid container 45, the washing fluid flows from the container 45 through the conduit 48 and the three-way valve 46 into the processing chamber 2, The object to be treated is washed with water inside the chamber. The flushing fluid is further supplied to a conduit 5, a dam mechanism 8, a return conduit 15 and a three-way valve 4.
7 and conduit 49, it flows again into the flushing fluid container 45 in the same way as before. According to this embodiment of the present invention, there is no need to move the object to be treated for washing, and the washing can be carried out in the processing chamber using a low-pressure circulation mechanism in the same way as during actual coating processing. is extremely advantageous. With this method, the water washing process can be carried out rapidly and without wasting any time.

An example in which hard chrome plating was performed using the treatment method according to the present invention under the above conditions and achieved very good results will be shown.

The electrolyte was a so-called self-regulating electrolyte (SRHS) and the temperature was adjusted according to the recommendations of the electrolyte manufacturer. The pressure inside the processing chamber is 0.85atm, and the current density is 100A/
dm ₂ and, despite the above conditions, a very robust and uniform coating process could be achieved.

Electrolyte SRHS110 Processing temperature 60°C Current density 80A/dm ^2Object to be processed Cylindrical cast iron pipe The present invention is not limited to the above-mentioned embodiments,
Various modifications can be made without departing from the scope of the claims.

[Brief explanation of the drawing]

Figure 1 shows the first part of the apparatus used in the treatment method of the present invention.
FIG. 2 is a side view showing the configuration of the embodiment; FIG. 2 is a side view showing the main parts of the second embodiment of the device;
FIG. 3 is a side view showing three embodiments of the above device. Symbols in the diagram: 1... Electrolyte tank, 2... Small processing chamber,
3...Large processing chamber, 4,16...Connecting pipe, 5,12,
15, 17, 48 and 49... conduit, 6... three-way valve,
7... Heat exchanger, 8... Weir mechanism, 9... Upper chamber, 1
0... Vacuum pump, 11, 24... Reverse feed valve, 13...
Lower chamber, 18... closed circuit for liquid cooling, 20... electric fan, 21... cooler, 22... circulation pump, 23... closing valve, 26, 27... cable, 25... electric heating device,
34... Electrolytic solution, 40... Packing for lead-in cable, 41... Electrode, 42... Treated object, 43... Air spring, 45... Washing fluid container, 46, 47... Three-way valve.

Claims (1)

[Scope of Claims] 1. An electroplating method in which the surface of an article to be metal coated is immersed in an electrolytic solution in an electrolytic treatment chamber and a current is passed between the article and the electrolyte to form a metal coating on the surface of the article. The space containing the electrolytic treatment chamber is sealed to prevent outside air from entering the space, and the electrolytic solution is circulated within the electrolytic processing chamber, and the pressure acting on the electrolytic solution in the space is reduced to 0.85 atmospheres or less. An electroplating method characterized by: 2. The method according to claim 1, wherein the electrolytic solution is appropriately cooled or heated during circulation. 3. The method according to claim 1, wherein the electrolyte is circulated to and from the outside of the space by low pressure acting on the electrolyte in the space. 4. The electrolytic treatment chamber is constituted by a container whose lower end is opened below the liquid level in the electrolytic solution tank, and the electrolytic treatment chamber is filled with the electrolytic solution to a desired liquid level by the low pressure generated inside the container. Method. 5. The treatment method according to claim 4, wherein the difference between the free liquid level in the electrolytic solution tank and the liquid level in the electrolytic treatment chamber is about 1.5 m or more. 6. The processing method according to claim 4, wherein an air spring is formed at the upper end of the interior of the low-pressure electrolytic processing chamber. 7 An electrolytic solution tank, a low-pressure electrolytic treatment chamber that can maintain a low pressure lower than atmospheric pressure, and a weir that circulates the electrolytic solution flowing from the electrolytic solution tank into the low-pressure electrolytic treatment chamber so that it returns back into the electrolytic solution tank. An electrolytic treatment device characterized by being provided with a stop circulation mechanism. 8. The processing apparatus according to claim 4, wherein the electrolytic solution tank is provided with a temperature adjustment mechanism. 9. The apparatus according to claim 7, wherein the low-pressure electrolytic treatment chamber is constituted by a container whose lower end opens below the liquid level in the electrolytic solution tank, and is connected to a pressure reducing device. 10 An electrolytic solution tank, a low-pressure electrolytic treatment chamber that can maintain a low pressure lower than atmospheric pressure, and a weir that circulates the electrolytic solution flowing from the electrolytic solution tank into the low-pressure electrolytic treatment chamber so that it returns back into the electrolytic solution tank. In a processing device equipped with a stop circulation mechanism, one or several containers for washing fluid are provided connected to the stop circulation mechanism, whereby the electrolyte tank and the stop circulation mechanism are communicated with each other. A processing device configured to connect one or more washing fluid containers to the circulation mechanism instead of the electrolyte tank so that the washing fluid flows and circulates within the mechanism.