Electrolytic polishing device for stainless steel tank, and electrolytic polishing method for polishing stainless steel tank

Abstract

To provide a small-sized electrolytic polishing device for a stainless steel tank, capable of applying electrolytic polishing to the whole of a large-sized stainless steel tank using a small amount of electrolytic polishing liquid and a small amount of electric power, and an electrolytic polishing method for a stainless steel tank.SOLUTION: An electrolytic polishing device 1 for a stainless steel tank comprises an electrolytic tank 2, an electrode 3, a handling crane 4 and a tank reversing machine 5, with the upper face of the electrolytic tank being configured to be opened so that at least a half of the stainless steel tank can be immersed in the electrolytic polishing liquid present in the electrolytic tank.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrolytic polishing device for stainless steel tanks and a method for electrolytic polishing of stainless steel tanks, and more particularly to an electrolytic polishing device for stainless steel tanks suitable for electrolytic polishing of large stainless steel tanks, and a method for electrolytic polishing of stainless steel tanks. Electrolytic polishing is a method for electrochemically removing and polishing a surface layer in micron units. [Background technology]

[0002] Conventionally, to perform electrolytic polishing on a large stainless steel tank, a large electrolytic tank capable of storing electrolytic polishing liquid for immersing the entire stainless steel tank was prepared, and electrolytic polishing was performed. In addition, the electrolytic polishing process required large electrolytic polishing equipment and a large amount of electrolytic polishing liquid.

[0003] However, conventional electrolytic polishing using a large electrolytic cell requires a large-scale electrolytic polishing facility using a wide space for electrolytic processing, which in turn requires a large amount of electrolytic polishing solution, and it takes a long time to store and discharge the electrolytic polishing solution, and there are problems with poor cost performance. In addition, in order to electrolytically polish the entire large stainless steel tank at once, a large amount of current must be passed, and for this, the rectifier and power supply / distribution transformer must also be capable of handling a large amount of current. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-172681 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide an electrolytic polishing device for stainless steel tanks that is specialized for space saving and contributes to the SDGs, and a method for electrolytic polishing of stainless steel tanks that is specialized for energy saving, which can perform entire electrolytic polishing with a small amount of electrolytic polishing liquid and a small amount of electricity. [Means for solving the problem]

[0006] The invention according to claim 1 is An electrode assembly having an electrolytic cell, an anode and a cathode; A transport crane that hoists and transports the stainless steel tank to be electrolytically polished; A tank inversion machine for inverting the stainless steel tank is provided, The tank inversion machine is installed near the electrolytic cell, the transport crane is installed in a position where the stainless steel tank can be transported between the electrolytic cell and the tank inversion machine, and the electrolytic cell has an open top and is configured so that at least half of the stainless steel tank can be immersed in the electrolytic polishing solution in the electrolytic cell.

[0007] The invention according to claim 2 relates to the electrolytic polishing device for a stainless steel tank according to claim 1, wherein the electrode body has a gripping portion for gripping the stainless steel tank.

[0008] The invention according to claim 3 relates to an electrolytic polishing apparatus for stainless steel tanks as described in claim 1, in which a leakage hole is provided on the inner side of the electrolytic layer to allow a certain amount of electrolytic polishing liquid to leak out.

[0009] The invention according to claim 4 is A method for electrolytic polishing a tank using the electrolytic polishing apparatus for stainless steel tanks according to any one of claims 1 to 3, (1) using the inverting machine to invert the stainless steel tank; (2) after the step (1), using the transport crane to transport the stainless steel tank from the inverting machine to the electrolytic cell and place the stainless steel tank in the electrolytic cell; (3) after step (2), electrolytically polishing at least half of the stainless steel tank; (4) after the step (3), transporting the stainless steel tank from the electrolytic cell to the inverting machine using a transport crane; (5) after the step (4), a step of inverting the stainless steel tank using the inverting machine; (6) after the step (5), using a transport crane to transport the stainless steel tank from the inverting machine to the electrolytic bath and place the stainless steel tank in the electrolytic bath; (7) After the step (6), a step of electrolytically polishing at least half of the stainless steel tank is included. Effect of the Invention

[0010] The electrolytic polishing device for stainless steel tanks according to claim 1 comprises an electrolytic cell, an electrode body having an anode and a cathode, a transport crane for lifting and transporting the stainless steel tank to be electrolytically polished, and a tank inverting machine for inverting the stainless steel tank, the tank inverting machine being installed near the electrolytic cell, the transport crane being installed in a position where the stainless steel tank can be transported between the electrolytic cell and the tank inverting machine, the electrolytic cell having an open top and configured so that at least half of the stainless steel tank can be immersed in the electrolytic polishing solution in the electrolytic cell, so that the entire tank can be electrolytically polished with a small amount of electrolytic polishing solution and a small amount of electricity. Electrolytic polishing can be performed even in a limited space without building a large facility as in the past.

[0011] According to the electrolytic polishing apparatus for stainless steel tanks of claim 2, the electrode body has a gripping portion for gripping the stainless steel tank, so that the stainless steel tank placed in the electrolytic cell can be gripped within the electrolytic cell and electrolytic polishing can be performed in a stable state.

[0012] According to the electrolytic polishing device for stainless steel tanks of claim 3, a leakage hole is provided on the inner side to allow a constant amount of electrolytic polishing liquid to leak out, so that the liquid level of the electrolytic polishing liquid can be stabilized at a constant level.

[0013] According to the electrolytic polishing method for stainless steel tanks of claim 4, there is provided an electrolytic polishing method using the electrolytic polishing apparatus for stainless steel tanks of claims 1 to 3, comprising the steps of: (1) inverting the stainless steel tank using the inverting machine; (2) after step (1), transporting the stainless steel tank from the inverting machine to the electrolytic bath and placing it in the electrolytic bath using the transport crane; (3) after step (2), electrolytically polishing at least half of the stainless steel tank; (4) after step (3), transporting the stainless steel tank from the electrolytic bath to the inverting machine using a transport crane; (5) after step (4), inverting the stainless steel tank using the inverting machine; (6) after step (5), transporting the stainless steel tank from the inverting machine to the electrolytic bath and placing it in the electrolytic bath using a transport crane; and (7) after step (6), electrolytic polishing at least half of the stainless steel tank. This allows electrolytic polishing to be performed using a small amount of electrolytic polishing liquid and little electricity. [Brief description of the drawings]

[0014] [Figure 1] 1 is a diagram showing an entirety of an electrolytic polishing apparatus for stainless steel tanks, which is one embodiment of the electrolytic polishing apparatus for stainless steel tanks according to the present invention. FIG. [Diagram 2] FIG. 2 is a diagram showing an electrolytic cell of the electrolytic polishing apparatus for stainless steel tanks according to the present invention. [Diagram 3] FIG. 2 is a diagram showing an electrode body of the electrolytic polishing apparatus for stainless steel tanks according to the present invention. [Figure 4] FIG. 2 is a diagram showing a transport crane of the electrolytic polishing apparatus for stainless steel tanks according to the present invention. [Diagram 5] FIG. 2 is a diagram showing a tank inverting machine of the electrolytic polishing apparatus for stainless steel tanks according to the present invention. [Figure 6] FIG. 2 is a diagram showing how a stainless steel tank, which is the subject of electrolytic polishing, is electrolytically polished in an electrolytic cell of the stainless steel tank electrolytic polishing apparatus according to the present invention. [Figure 7] 1 is a diagram showing the principle of electrolytic polishing, which is an embodiment of an electrolytic polishing apparatus for stainless steel tanks according to the present invention. FIG. [Figure 8] FIG. 1 is a diagram showing the steps of electrolytic polishing treatment in one embodiment of an electrolytic polishing device for stainless steel tanks according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an electrolytic polishing apparatus for a stainless steel tank according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0016] <Electrolytic polishing equipment for stainless steel tanks>

[0017] Referring to FIG. 1, an electrolytic polishing apparatus (1) for a stainless steel tank according to this embodiment includes an electrolytic cell (2), an electrode body (3), a transport crane (4), and a tank inverting machine (5).

[0018] 1, 2, and 6, the electrolytic cell (2) according to this embodiment has a depth and width at least half the diameter of the stainless steel tank (ST) to be electropolished, a width corresponding to the height of the stainless steel tank to be electropolished, and a size large enough to accommodate the stainless steel tank to be electropolished. Here, Fig. 2(a) is a plan view of the electrolytic cell (2) seen from above, and Figs. 2(b) and 2(c) are side views.

[0019] The electrolytic cell (2) also has a liquid level sensor (29) that detects the liquid level of the electrolytic polishing liquid (28) stored in the electrolytic cell (2), a temperature sensor (30) that detects the temperature of the electrolytic polishing liquid (28), an overflow function that stabilizes the liquid level of the immersed electrolyte in the stainless steel tank (ST) when electrolytic polishing the stainless steel tank (ST) in the electrolytic cell (2), and a circulator (10) that improves the efficiency of processing. The electrolytic cell (2) also has a discharge flange that discharges the electrolytic polishing liquid (28) stored in the electrolytic cell (2).

[0020] In this embodiment, to provide an overflow function, the electrolytic cell (2) has a two-layer structure divided into an upper section (6) and a lower section (7). The lower section (7) is formed in a tank shape with an opening on the top, and the upper section (6) is formed so as to surround the vicinity of the opening of the lower section (7). The upper section (6) is formed with a leakage hole (9) that allows the electrolytic polishing solution (28) overflowing from the lower section (7) to leak out.

[0021] When an amount of electrolytic polishing liquid (28) that exceeds the opening of the lower stage (7) is poured into the electrolytic cell (2), the electrolytic polishing liquid (28) overflows from the opening of the lower stage and is stored in the upper stage (6), and then leaks out from the leakage hole (9).

[0022] The electropolishing liquid (28) leaking from the leak hole (9) in the upper stage (6) is sucked by a pump, which is a circulator (10), and sent to the lower stage (7). This allows the electropolishing liquid (28) to circulate.

[0023] The configuration of the overflow function is not limited to this, and may be such that a leakage hole (9) is provided on the inner side surface of the electrolytic cell (2).

[0024] The heater (8) heats the electropolishing solution (28) to 60°C to 90°C.

[0025] When the electrolytic polishing liquid (28) is below 60°C, the disadvantages are that the luster is lost, the surface becomes whitish, the surface becomes rough, etc. When the electrolytic polishing liquid (28) is above 90°C, the disadvantages are that, although electrolytic polishing is completed in about 3 minutes at 90°C, which is shorter than the approximately 10 minutes at 60°C, the condition of the polished surface is not stable because the time is too short, and it is difficult to check the process during the process because the electrolytic polishing liquid (28) is not transparent, and the corresponding electricity costs increase. These disadvantages can be avoided by heating the electrolytic polishing liquid (28) from 60°C to 90°C using the heater (8).

[0026] Furthermore, the electrolytic cell (2) or the electrode body (3) may have a gripping portion (27) as a positioning jig for fixing the position of the stainless steel tank (ST) that is the object of electrolytic polishing.

[0027] The electrolytic polishing device (1) for stainless steel tanks further includes a power source such as a rectifier, which is a DC power source for applying voltage to the stainless steel tank (ST), and the power source is connected to the stainless steel tank (ST), which is the object of electrolytic polishing, and the electrode body (3) via a plug box or the like.

[0028] Referring to FIG. 3, the electrode body (3) according to this embodiment has an anode (11) and a cathode (12). One of the anode (11) and the cathode (12) is formed by assembling a plurality of electrode supports (13) like a beam. The material of the plurality of electrode supports (13) is oxygen-free copper or the like. The other electrode is a clamp or the like attached to the stainless steel tank (ST). In this embodiment, the electrode support (13) is the anode (11), and the one attached to the leg of the stainless steel tank (ST) is the cathode (12). Here, FIG. 3(a) is a vertical cross-sectional view of the stainless steel tank (ST), and FIG. 3(b) is a cross-sectional view of the stainless steel tank (ST) in FIG. 3(a) as viewed in the direction of the arrow BB.

[0029] As shown in FIG. 3(a), each of the electrode supports (13) has a mounting hole (15) for mounting a joint metal fitting (USU3t) (14), and the electrode supports (13) are assembled by bolting the joint metal fitting (14) into the mounting hole (15). The number of electrode supports (13) and the angle of the electrode supports (13) arranged at an angle can be changed according to the shape and weight of the stainless steel tank (ST) to be electropolished. The anode (11) is assembled like a tent by assembling the electrode supports (13) like beams and stretching electrode plates (17) on their outer surfaces. If the electrode supports (13) require rigidity, a reinforcing member (16) can be used. The reinforcing member (16) is shaped to match the shape of the electrode supports (13) and reinforces the connection between the electrode supports (13) and the joint metal fitting (14).

[0030] Since the electrolytic polishing device for stainless steel tanks (1) of the present invention is formed by assembling multiple electrode supports (13), the assembly can be changed to suit the shape and size of each stainless steel tank (ST), so that the electrolytic polishing device for stainless steel tanks (1) of the present invention can electrolytically polish stainless steel tanks of various shapes and sizes.

[0031] An electrode plate (17) is attached to the outer surface of the assembled electrode support (13). The electrode plate (17) is made of punched metal with holes at uniform intervals. A keyhole-machined locking hole (18) is formed in the electrode plate (17), and a co-rotation prevention bolt (19) is used to attach the electrode plate (17) to the electrode support (13). Since the co-rotation prevention bolt (19) is used, even when a worker enters a large stainless steel tank (ST) to assemble the anode (11), the electrode plate (17) can be hung on the co-rotation prevention bolt (19) through the keyhole-machined locking hole (18) and the nut can be fastened from the inside of the electrode plate (17), making it easy to attach the electrode plate (17) to the electrode support (13).

[0032] An example of the weight of the electrode plates (17) arranged on the bottom surface is 9.5 kg + 2.6 kg, which is a total of 12.1 kg. An example of the weight of the eight electrode plates arranged on the side surface is 18.7 kg x 0.77 kg, which is a total of 14.4 kg.

[0033] As shown in FIG. 3(b), the electrode support (13) is assembled only to the inner half of the stainless steel tank (ST) and is formed into a shape that combines a square pyramid shape and a square prism shape to match the shape of the inner surface of the tank.

[0034] The cathode (12) is shaped like a small vice and is attached by clamping the legs of the stainless steel tank (ST).

[0035] Referring to Fig. 4, the transport crane (4) according to this embodiment has a jig (20) for lifting the tank. The jig (20) is used to lift and raise the stainless steel tank (ST) to be electropolished, and to lower it. The transport crane (4) is operated by a hoist on the factory side, and the device is preferably operated by a wire suspension system.

[0036] Referring to FIG. 5, the tank inverting machine (5) according to this embodiment has a gear box (21) in which a worm gear and a worm wheel are housed. The worm gear has a worm gear shaft, and the worm wheel has a worm wheel shaft. A handle is connected to the worm wheel shaft, and a shaft of the tank inverting machine (5) is connected to the worm gear shaft. When the handle is rotated, the worm wheel rotates via the worm wheel shaft connected to the handle. The rotation of the worm gear shaft rotates the shaft, thereby inverting the stainless steel tank (ST) placed on the tank inverting machine (5).

[0037] The procedure for turning a stainless steel tank (ST) upside down is to set the stainless steel tank (ST) on the tank inversion machine (5) and turn the handle, for example, to the "right". The stainless steel tank (ST) will then be turned sideways. The stainless steel tank (ST) is then lifted slightly with the transport crane (4), rotated horizontally to change the orientation of the top, and then reset on the tank inversion machine (5). The handle is then turned to the "left". This will turn the stainless steel tank (ST) upside down.

[0038] 1 and 6, in the electrolytic polishing device (1) for stainless steel tanks according to this embodiment, a stainless steel tank (ST) to be electrolytically polished is placed sideways in an electrolytic bath (2) that stores an electrolytic polishing liquid (28). The electrolytic polishing liquid (28) is set so that when the stainless steel tank (ST) is immersed in the electrolytic polishing liquid (28), the liquid level immerses at least half of the stainless steel tank (ST). When the electrolytic polishing liquid (28) is poured into the electrolytic bath (2) to a capacity equal to or greater than the capacity of the lower stage (7), the electrolytic polishing liquid (28) overflows from the opening of the lower stage (7), so that the liquid level in the electrolytic bath (2) does not rise above the opening of the lower stage (7). This configuration makes it possible to stabilize the liquid level of the electrolytic polishing liquid (28).

[0039] An electric chemical hand pump is used to transport the electrolytic polishing solution 28, and the electrolytic polishing solution 28 is filled and discharged. The order of the initial liquid addition is phosphoric acid, sulfuric acid, and chromic acid aqueous solution.

[0040] The electropolishing solution (28) used in this embodiment has a composition in which the concentrations of the components are approximately 60 wt % phosphoric acid, 22 wt % sulfuric acid, and 1.5 wt % chromic acid. By using the electropolishing solution (28) with this composition, a better finish can be achieved compared to electropolishing solutions (28) with other compositions.

[0041] The method of filling is as follows: if the level of electrolytic polishing liquid (28) drops below 900 mm due to removal of the liquid, an alarm is sounded. Electrolytic polishing liquid (28) (new liquid) that has been mixed offline is added using an electric hand pump in the same manner as above. The electrolytic polishing liquid (28) is discharged via piping connected to the discharge flange at the bottom of the tank, stored in a water storage tank at an outdoor facility, and then collected and disposed of as industrial waste outside.

[0042] As shown in FIG. 1, the stainless steel tank electrolytic polishing apparatus (1) may further include a pure water overflow cleaning tank (22). The pure water overflow cleaning tank (22) has a pure water piping (23), through which the pure water after the completion of the pure water cleaning can be sent to another location and reused. The pure water used in the pure water overflow cleaning tank (22) can be reused for cleaning the alkaline degreasing solution, cleaning the electrolytic polishing solution (28) after electrolytic polishing, and the like. By reusing the used pure water, the cost required for the pure water can be reduced.

[0043] The stainless steel tank electrolytic polishing apparatus (1) may further include an alkaline degreasing tank (24). The alkaline degreasing tank (24) has a pump and a heater, and can maintain the alkaline solution at a constant temperature. Since the stainless steel tank (ST) can be transported by the transport crane (4), only one alkaline degreasing tank (24) can be used in the electrolytic treatment process.

[0044] The stainless steel tank electropolishing apparatus (1) may further include a jig assembly / removal stand (26) and an elevator (25) used for assembling the electrode body (3). The elevator (25) raises the stainless steel tank (ST), allowing an operator to enter the stainless steel tank (ST) at the jig assembly / removal stand (26) to easily assemble or remove the electrode body (3).

[0045] <Principle of electrolytic polishing> As shown in Figures 6 and 7, the principle of electrolytic polishing is as follows. As shown in Figure 7(a), first, the anode (11) and cathode (12) of the electrode body (3) are placed in the stainless steel tank (ST), and the electrode body (3) is connected to a rectifier or the like as a power source, and current flows through the stainless steel tank (ST) through the electrolytic polishing liquid (28). As shown in Figures 7(b) and 7(c), an initial oxide (31) with a thickness of about 10 μm is formed a few seconds after the current is passed through. The initial oxide (31) has a sufficiently large electrical resistance compared to the electrolytic polishing liquid (28). Therefore, the resistance of the electrolytic polishing liquid (28) is ignored, and it is electrically equivalent to the cathode approaching very close to the initial oxide (31). Therefore, more current flows through the thin parts of the initial oxide (31), and the stainless steel flows out quickly, whereas the current through the thick parts of the initial oxide (31) is smaller, and the dissolution rate is slower.

[0046] Due to the difference in dissolution rate, the surface of the stainless steel gradually becomes flat. At this time, iron dissolves slightly faster than chromium, so iron dissolves preferentially on the stainless steel surface. As a result, chromium is concentrated.

[0047] As shown in Figure 7(d), the surface of the stainless steel tank (ST) forms a strong passive film (32). Since the passive film (32) has a much higher electrical resistance than stainless steel, current flows preferentially through the thinner parts of the passive film (32), which results in the thinner parts of the passive film (32) becoming thicker, resulting in a uniform thickness of the passive film (32). It is believed that oxidation and reduction occur simultaneously at the anode.

[0048] <Electrolytic polishing process> The process of electrolytic polishing will be described below with reference to FIG. 1, FIG. 6, and FIG. 8. In the electrolytic polishing process according to this embodiment, the stainless steel tank (ST) is washed with water near the jig assembly removal stand (26), and then the surface oil and grease are degreased with an alkaline degreasing liquid in an alkaline degreasing tank (24) in order to perform uniform electrolytic polishing. After the degreasing is completed, the tank is washed with water to clean the alkaline degreasing liquid. The stainless steel tank (ST) is turned upside down using a transfer crane (4) and a tank inverting machine (5). The stainless steel tank (ST) is transferred to the jig assembly removal stand (26) and elevated by a lifting machine (25), and jig assembly (first time, electrode jig installation 1) is performed to install a jig, which is an electrode body (3). In order to put the stainless steel tank (ST) into the electrolytic cell (2), the tank inverting machine (5) is used to invert the stainless steel tank (ST) 90 degrees to turn it sideways. A plug is set to connect the electrode body (3) to the stainless steel tank (ST). The stainless steel tank (ST) is lowered by the transport crane (4) and half of its body is immersed in the electrolytic polishing liquid (28) in the electrolytic cell (2). The inside of the half of the stainless steel tank (ST) is electrolytically polished (first time).

[0049] The stainless steel tank (ST) is raised by the transport crane (4), and a plug release is performed to remove the electrodes connected to the stainless steel tank (ST). The stainless steel tank (ST) is left standing while being lifted by the transport crane (4), and the electrolytic polishing liquid (28) accumulated in the stainless steel tank is returned to the electrolytic cell (2). The tank inverting machine (5) inverts the stainless steel tank (ST) 90 degrees to make it vertical. The tank is rinsed with water to clean the electrolytic polishing liquid (28). Air is blown to dry the stainless steel tank (ST). The stainless steel tank (ST) is transferred to the jig assembly removal stand (26), and the electrode body (3) is removed (first time). The vicinity of the half-body part that was half-immersed in the electrolytic polishing liquid (28), i.e., the location where the liquid level of the electrolytic polishing liquid (28) was, is masked to prevent the electrolytic polishing process from overlapping between the first and second times, and to prevent unevenness in the electrolytic polishing.

[0050] The stainless steel tank (ST) is transferred to the jig assembly removal stand (26) and elevated by the elevator (25), and the jig, which is the electrode body (3), is installed on the opposite side, performing jig assembly (second time, electrode jig installation 2 (opposite side)). The stainless steel tank (ST) is turned 90 degrees by the tank inverting machine (5) and placed on its side. Plugs are set to connect the electrodes to the stainless steel tank. The stainless steel tank (ST) is lowered by the transport crane (4) and half of its body is immersed in the electrolytic polishing solution (28) in the electrolytic cell (2). Electrolytic polishing (second time) is performed on the inside of the half of the stainless steel tank, etc.

[0051] The stainless steel tank (ST) is lifted by the transfer crane (4) and a plug release is performed to remove the electrodes connected to the stainless steel tank (ST). The stainless steel tank (ST) is lifted by the transfer crane (4) and left to stand, and the electrolytic polishing liquid (28) accumulated in the stainless steel tank (ST) is returned to the electrolytic cell (2). The tank inverting machine (5) turns the stainless steel tank (ST) 90 degrees to turn it upright. It is rinsed with water to clean the electrolytic polishing liquid (28). Air is blown to dry the stainless steel tank (ST). It is transferred to the jig assembly removal stand (26) and raised by the elevator (25), and the electrode body (3) is removed from the stainless steel tank (ST) (for the second time). A visual inspection is performed and the process moves to the post-processing process. The stainless steel tank (ST) is turned upside down by the transfer crane (4) and the tank inverting machine (5). The stainless steel tank (ST) is subjected to high-pressure jet cleaning. Air is blown to dry the stainless steel tank (ST).

[0052] Even if the stainless steel tank (ST) is large, it can be transported between the electrolytic cell (2), the tank inverting machine (5), and the jig assembly and removal stand (26) by the transport crane (4). In addition, since the electrode body (3) can be assembled only on half of the stainless steel tank (ST) using the tank inverting machine (5), the elevator (25), and the jig assembly and removal stand (26), it is possible to perform stable electrolytic polishing of the electrolytically polished surface of the large stainless steel tank (ST) with a small amount of electrolytic polishing liquid (28) even in a limited space. In addition, the configurations and conditions of the stainless steel tank electrolytic polishing device (1) according to this embodiment are not limited to this embodiment, and various modifications, corrections, and changes can be made within the scope of what is obvious to those skilled in the art.

[0053] <Each polishing condition of electrolytic polishing (e.g. voltage, processing time, etc.)> The polishing conditions for the electrolytic polishing in this embodiment are as follows: The power for the electrolytic polishing is 16,000 A in total, using two 8,000 A rectifiers, and the current density is about 30 A / cm 2 It is.

[0054] <Details of the electrolytic polishing process> Details of each process in the electrolytic polishing process of this embodiment are as follows. In the alkaline cleaning process, 60°C hot water is used for cleaning, and when alkaline cleaning the stainless steel tank (ST) that is the target of electrolytic polishing, a worker climbs onto a built-in work step and uses a hand shower to clean it. When suspending the stainless steel tank (ST) with the transfer crane (4), wires of different lengths are used to create an incline so that the electrolytic polishing liquid (28) after electrolytic polishing returns to the tank. A circulation pump is used for degreasing, and there is a cover to prevent the liquid from splashing. A 7.5 kW compressor is used in the maintenance area. [Industrial Applicability]

[0055] The electrolytic polishing apparatus for stainless steel tanks of the present invention can provide an electrolytic polishing apparatus for stainless steel tanks that is suitable for electrolytic polishing large stainless steel tanks, and the electrolytic polishing apparatus for stainless steel tanks of the present invention can greatly contribute to performing entire electrolytic polishing with a small amount of electrolytic polishing liquid and a small amount of electricity, even in the case of a large tank. [Explanation of symbols]

[0056] 1. Electrolytic polishing equipment for stainless steel tanks 2 Electrolytic cell 3 Electrode body 4. Transport crane 5 Tank inversion machine 6 Upper 7 Lower 8. Heater 9 Leak hole 10 Circulatory system 11 Anode 12 Cathode 13 Electrode post 14 Joint fittings 15 Mounting hole 16 Reinforcement 17 Electrode plate 18 Locking hole 19 Anti-rotation bolt 20 Jig 21 Gearbox 22 Pure water overflow cleaning tank 23 Pure water piping 24 Alkaline degreasing tank 25 Elevator 26 Jig assembly removal stand 27 Gripping part 28 Electrolytic polishing liquid 29 Liquid level sensor 30 Temperature Sensor 31 Initial oxide 32 Passive Film ST Stainless Steel Tank

Claims

1. An electrolytic cell; An electrode assembly having an anode and a cathode; A transport crane that lifts and transports the stainless steel tanks to be electrolytically polished, A tank inversion machine for inverting the stainless steel tank; Equipped with The tank inverting machine is installed near the electrolytic cell, the transport crane is installed at a position where the stainless steel tank can be transported between the electrolytic cell and the tank inverting machine; The electrolytic cell has an open top and is configured so that at least half of the stainless steel tank can be immersed in the electrolytic polishing solution in the electrolytic cell.

2. 2. The electrolytic polishing apparatus for a stainless steel tank according to claim 1, wherein the electrode body has a gripping portion for gripping the stainless steel tank.

3. 2. The electrolytic polishing apparatus for stainless steel tanks according to claim 1, wherein the electrolytic cell is provided on an inner side thereof with a leakage hole for allowing a certain amount of electrolytic polishing solution to leak out.

4. A method for electrolytic polishing a tank using the electrolytic polishing apparatus for stainless steel tanks according to any one of claims 1 to 3, (1) using the inverting machine to invert the stainless steel tank; (2) after the step (1), using the transport crane to transport the stainless steel tank from the inverting machine to the electrolytic bath and place the stainless steel tank in the electrolytic bath; (3) after the step (2), electrolytically polishing at least half of the stainless steel tank; (4) after the step (3), a step of transporting the stainless steel tank from the electrolytic cell to the inverting machine using a transport crane; (5) after the step (4), a step of inverting the stainless steel tank using the inverting machine; (6) after the step (5), using a transport crane to transport the stainless steel tank from the inverting machine to the electrolytic bath and place the stainless steel tank in the electrolytic bath; (7) A method for electrolytically polishing a stainless steel tank, comprising the step of electrolytically polishing at least half of the stainless steel tank after the step (6).

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