JP2015059255A - Electrolytic polishing apparatus for hollow tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing apparatus for hollow tubes arranged vertically.SOLUTION: In an electrolytic polishing apparatus for polishing the inside surface of a hollow tube, a liquid guide chamber formed with a liquid circulation port at a position of a specified height is provided at the upper end of the hollow tube. An electrolytic solution is injected from the lower end of the hollow tube by liquid circulation means and circulated from the hollow tube through the liquid circulation port of the liquid guide chamber. Bubble detection means detects bubbles staying at positions above a waterline in the vicinity of the liquid circulation port of the liquid guide chamber. Control means controls the bubble formation condition according to the state of detected bubbles. The bubble detection means preferably uses an optical sensor detecting transmission of light on the upper side of the waterline of the liquid guide chamber.

Description

  The present invention relates to an electrolytic polishing apparatus for electrolytic polishing an inner surface of a hollow tube.

  A linear collider is being built as a device that collides positrons and negative electrons to form a big bang state (ILC project). As shown in FIG. 5, the linear collider uses a niobium hollow tube 100 having flanges 101a and 101b at both ends and whose diameter periodically changes in the axial direction. One of the factors for obtaining a predetermined effect in an experiment using a linear collider is whether or not the inner surface of the niobium hollow tube 100 is smooth.

  However, since the hollow tube 100 is subjected to excessive pressure and heat during molding, the structure of the inner surface thereof is unevenly distorted. If this surface state is left as it is, the electrical and magnetic characteristics are also non-uniform, and as a result, a predetermined speed cannot be given to electrons and protons. Therefore, a method of polishing the inner surface of the hollow tube to a predetermined thickness has been developed.

  As a method for polishing a niobium hollow tube, two types are known: a method of polishing chemically (hereinafter referred to as “chemical polishing”) and a method of polishing electrochemically (hereinafter referred to as “electrolytic polishing”). .

  The chemical polishing method immerses the entire hollow tube in the electrolytic solution, so the operation itself is simple, but the outer surface of the originally unnecessary hollow tube is polished to promote unnecessary contamination, aging and deterioration of the liquid, and to be polished. There is a problem that the amount of polishing varies significantly depending on the immersion direction of the object. In addition, depending on the shape of the hollow tube, the generated gas has many disadvantages such as adhering to the inner surface and impairing the polished state.

  Examples of electrolytic polishing include the following.

  In Japanese Patent Publication No. 55-12116, the both ends of the hollow tube of niobium are leveled, and the lower half of the hollow tube is partially immersed in an electrolytic solution of hydrofluoric acid, sulfuric acid, and water. Discontinuous electropolishing is disclosed in which energization is performed for a short time, partial electropolishing is performed, and then the energization is stopped and then rotated to dissolve and remove the oxide film many times.

  This method also inherently polishes the outer surface of the hollow tube that does not require polishing, which causes unnecessary dissolution loss of the hollow tube and unnecessarily consumes and contaminates the electrolyte. In addition, polishing steps occur due to intermittent polishing, and in addition, it is extremely dangerous work that handles hydrofluoric acid that generates volatile gas with high volatility and sulfuric acid with high heat generation. Yes.

  In the invention disclosed in Japanese Patent Application Laid-Open No. 61-23799, while rotating a niobium hollow tube, an electrolytic solution is fed from a blowout hole communicating with a liquid passing pipe, and continuous electrolysis is attempted in a partially immersed state. ing. With this configuration, the polishing time can be shortened, and at the same time, the niobium material is not melted unnecessarily. Therefore, unnecessary contamination and consumption of the electrolyte are suppressed.

  However, since the blowout hole provided in the liquid passage pipe is opened in the electrolyte and discharged into the stored electrolyte, a difference in the flow rate of the electrolyte appears in the polishing state. There was a problem that unevenness of the polished appearance was caused on the inner surface of the niobium hollow tube.

  The invention disclosed in Japanese Patent Application Laid-Open No. 11-350200 is basically the same as the invention disclosed in the above Japanese Patent Application Laid-Open No. 61-23799, except that the outlet hole provided in the liquid flow pipe is opposite to the side to be polished. In order to achieve uniform polishing, an opening is made above the electrolyte solution so that the electrolyte solution does not flow directly into the stored electrolyte solution.

JP 61-23799 JP-A-11-350200

  When electrolytic polishing is used for polishing the inner surface of the hollow tube, if the treatment of the generated gas is not appropriate, the portion that has come into contact with the gas becomes cloudy or conversely becomes black. In particular, the cavity tube as a linear collider accelerator that the present application mainly intends to deal with has a structure in which the inner diameter periodically changes, and even in the case of electrolytic polishing in a horizontal state, even in the case of electrolytic polishing in a vertical direction, It has a shape in which gas tends to stay inside.

  In any of the above-described conventional electropolishing methods, the hollow tube is in a horizontal direction, and gas is clearly retained. It is not clear how the accumulated gas is released to the outside.

  In the international application JP2013-068593, the applicant of the present application discloses an electrode that can be electropolished with the hollow tube in a vertical state, together with an electropolishing apparatus using the electrode.

  According to this, since the electrode has a blade that changes in shape along the inner surface of the hollow tube, the inner surface can be polished with high accuracy. In this case, since the hollow pipe is installed vertically, it is less likely that the gas stays inside the hollow pipe than the conventional techniques. However, since the inside diameter of the hollow tube changes periodically, the gas generated is highly likely to stay inside from this point of view, and the gas staying inside cannot be visually observed from the outside. There is a fear of significantly lowering.

  The present invention has been proposed in view of the above-described conventional circumstances, and does not cause the gas generated during electropolishing to stay in the hollow tube, and detects the gas when it is generated and circulates the electrolyte. An object of the present invention is to provide an electrolytic polishing apparatus capable of controlling the amount and polishing current.

  The present invention is premised on an electropolishing apparatus for electropolishing the inner surface of a hollow tube with an electrode inserted in the axial direction.

  In the electropolishing apparatus, a liquid lead-out chamber provided with a liquid circulation port at a predetermined height is provided at the upper end of the hollow pipe. The electrolytic solution is injected from the lower end of the hollow tube into the hollow tube by the liquid circulation means, and the electrolytic solution is further circulated from the hollow tube through the liquid circulation port of the liquid outlet chamber. The bubble detection means detects bubbles staying at a position above the water line near the liquid circulation port of the liquid outlet chamber. The control means controls the bubble generation state according to the detected bubble state. That is, the voltage used for electrolysis or the flow rate of the circulating electrolyte is controlled.

  The bubble detection means preferably uses an optical sensor that detects transmission of light above the water line of the liquid outlet chamber.

  The gas generated in the electrolyte during electropolishing is in the form of bubbles. With the above configuration, when bubbles are generated in the electrolytic solution, the electrolytic solution circulates through the hollow pipe from the lower side to the upper liquid outlet chamber, and thus the generated gas rises to the draft of the liquid outlet chamber. . Therefore, if bubbles stay at the waterline position, the optical sensor will work. In response to this, the control means performs control such as increasing the circulation rate of the electrolytic solution or decreasing the electrolytic current, and can maintain a state in which no gas stays.

The side view which shows the principal part of the apparatus of this invention The side view which shows the whole apparatus of this invention Unit electrode used in the present invention Overall view of electrodes used in the present invention Overall view of hollow tube

  FIG. 1 is a view showing a state where a hollow tube is subjected to electric field polishing using an apparatus according to the present invention.

  A gantry 11 is provided on the gantry 10, and a hollow pipe 100 as an object to be polished is fixed to the upper side of the gantry 11 using one flange 101 a. A liquid introduction chamber 14 is provided below the pedestal 11 so as to maintain liquid permeability with the hollow tube, and an electrolytic solution is supplied to the liquid introduction chamber 14 from an electrolyte tank 15 via a pump 16. The liquid can be introduced into the hollow tube 100 placed on the gantry 11 via the liquid introduction chamber 14.

  In this state, the electrode 20 is inserted from the upper end of the cavity tube 100. This electrode may be a rod having a predetermined thickness, but here, the electrode disclosed in International Application JP2013-068593 is used, and the structure of the electrode 20 itself and the insertion method will be described later. .

  After the electrode 20 is inserted, a transparent liquid outlet chamber 19 is mounted on the upper flange 101 b of the cavity tube 100. As shown in FIG. 2, the liquid lead-out chamber 19 is formed of a cavity having an upper base at a predetermined height, and a circulation port through which an electrolyte that circulates is discharged at a position about half the predetermined height as follows. 191 is provided. The circulation port 191 is configured to communicate with a circulation hose 192 that returns the discharged electrolyte solution to the electrolyte tank 15.

  The position of the circulation port 191 serves as a water line of the electrolyte, and corresponding to the water line, there is provided an optical sensor 40 that emits light from the light emitting element 40a from one outside in the radial direction and receives light from the light receiving element 40b on the other side. . When bubbles are generated during the electrolytic treatment, the bubbles rise above the water line and stay, and the optical sensor 40 can detect the presence of the bubbles.

  The output of the optical sensor 40 is input to the control means 50, and when the generation of bubbles is detected, control is performed to suppress the generation of bubbles, which will be described later.

  A gas discharge port 194 is provided in the vicinity of the upper bottom of the liquid lead-out chamber 19 so that the gas generated during the electrolytic process is discharged by being drawn by the decompression pump 80. An adjustment valve 81 is provided on the side facing the gas discharge port 194, and the suction force of the decompression pump 80 can be adjusted by opening and closing the valve. In addition, a second discharge port 193 is preliminarily provided above the discharge port 191 and below the gas discharge port 194. When a large amount of excessive bubbles stays, the second discharge port 193 is connected to the second discharge port 193. The electrolyte tank 15 is returned via a hose 195.

  The entire hollow tube 100 is housed in an air conditioning cover 61, and the atmosphere of the air conditioning cover 61 is adjusted to a predetermined temperature by the heat exchanger 60. Further, the electrolytic solution in the electrolytic solution tank 15 is cooled by the cold water in the chiller 70. Furthermore, in this case, an electrode having a wing disclosed in International Application JP2013-068593 is used, and a driving means 120 for slowly rotating the electrode 20 is provided.

  With the above configuration, before the start of the electrolytic treatment, the liquid supply pump 16 fills the hollow pipe 100 with the electrolytic solution from the electrolytic solution tank 15 through the liquid introduction chamber 14, and further from the hollow pipe 100 through the liquid outlet chamber 19. Then, the electrolytic solution is circulated from the circulation port 191 of the liquid discharge chamber 19 to the electrolytic solution tank 15 through the circulation hose 192. This circulation is continuously performed at a predetermined flow rate, and the speed of the electrolytic solution is kept constant.

  As the electrolysis progresses and the liquid temperature rises, the electrolysis reaction becomes intense, and bubble gas is generated in the form of bubbles inside the hollow tube 100.

  The bubbles pushed out or floated to the liquid outlet chamber 19 according to the circulation of the liquid will float up to the water line near the circulation port 191, and when the bubbles are not generated or when there are few bubbles, the light emitting element. The light beam from 40a is received by the light receiving element 40b, but when the number of bubbles increases, the light from the light emitting element is blocked.

  When the light is blocked, an excessive electrolytic treatment is performed, so that the control means 50 performs control to suppress the generation of bubbles. Control for suppressing the generation of bubbles includes reducing the electrolysis current, increasing the circulation amount of the liquid by controlling the pump 16, lowering the ambient temperature in the air conditioning chamber 61 by controlling the heat exchanger 60, chiller It is conceivable that the liquid temperature is lowered by controlling 70, and the pressure in the liquid outlet chamber 19 is forcibly discharged by the decompression pump 70 and the valve 71. In this case, an electrode disclosed in International Application JP2013-068593 is used. Since the rotation speed of the electrode is also related to the generation of bubbles, the generation of bubbles can be controlled by controlling the number of rotations of the electrode by the driving means 120. By taking at least one of the above measures to suppress the generation of bubbles, the surface after electropolishing can be kept in a satisfactory state.

  As an electrode for electropolishing in the hollow tube 100, it is conceivable to insert a straight electrode rod at the position of the axis of the hollow tube 100. However, the applicant of the present application disclosed an international application JP2013-068593 with a hollow tube. Since an application for an electrode for electropolishing has been filed, a brief description will be given below.

  FIG. 3 shows a unit electrode 20 corresponding to one bulge of the hollow tube 100.

  At least one single blade 22a, 22b,... Corresponding to the inner shape of the bulge of the hollow tube 100 is attached to the electrode shaft 21. The single blades 22a, 22b,... Have flexibility and can be wound around the electrode shaft 21. On the other hand, a storage cylinder 29 provided with slits 23 a, 23 b... In the axial direction is prepared at positions corresponding to the single blades 22 a, 22 b..., And the single blades 22 a, 22 b. The storage cylinder 29 is inserted into the electrode shaft 21 in the inserted state. As a matter of course, the storage cylinder 29 has a larger diameter than the electrode shaft 21, and a spacer 30 is interposed between the storage tube 29 and the electrode shaft 21.

  Accordingly, when the storage cylinder 29 is rotated in one direction with respect to the electrode shaft 21, the single blades 22a, 22b,... Are wound around the electrode shaft 21 and are stored in the storage cylinder 29 (storage state). ). When the storage state is formed with the tips of the single blades 22a, 22b,... Slightly protruding from the tips of the slits 23a, 23b, and then the storage tube 29 is rotated to the other side with respect to the electrode shaft 21, the single blades 22a, 22b... Extend from the electrode shaft 21. Each of the single blades 22a, 22b,... Is flexible, and the shape of each single blade 22a, 22b,... Matches the shape of the inner peripheral surface of the cavity tube 100. The distance between the peripheral ends of 22b,... And the inner surface of the hollow tube 100 is substantially constant at any point and approaches a distance suitable for electrolytic polishing (operation state). As a result, when a predetermined electric field is applied and the electrode 20 is slowly rotated, the inner surface of the hollow tube 100 can be uniformly electropolished without unevenness.

  In FIG. 3, each single blade 22a, 22b,... Is formed of a metal net. There are various structures or materials for giving flexibility to the single blades 22a, 22b,... In FIG. 3, the synthetic resin plates 221a, 221b,. The base end (electrode shaft side) is pasted to the front end. Further, in FIG. 3, auxiliary electrodes 220 a, 220 b... That are long in the circumferential direction are provided at positions corresponding to the bulge apexes of the hollow tube 100 at the tips of the single blades 22 a, 22 b. I try not to run out of polishing.

  Further, in order to go from the storage state to the operation state or vice versa, the storage tube 29 is pressed by hand and the electrode shaft 21 is rotated against the frictional force. In order to rotate, it is sufficient to apply a weak rotational force to the electrode shaft 21.

  FIG. 4 shows an electrode corresponding to the hollow tube 100 having a plurality of bulges.

  Each of the single blades 22 a, 22 b... Is provided with a pair of blade electrodes 22 corresponding to the number of bulges in the axial direction of the electrode shaft 21, and a storage cylinder 29 is disposed on the electrode shaft 21 via a spacer 30. Inserted. At this time, the relationship between each single blade 22a, 22b,... Of each blade electrode 22 and the slits 23a, 23b,.

  The electrode 20 is inserted coaxially from above the hollow tube 100 installed on the gantry 11, but when inserted, the electrode 20 is inserted in the housed state, and then in an operating state to perform the electrolytic polishing. become.

  After the electrolytic polishing process is completed, the electrode 20 is pulled out in the housed state.

  When electrolytic treatment is performed using the electrode 20, the electrode 20 rotates slowly with respect to the hollow tube 100, and the electrolytic solution circulates at a predetermined speed. Further, each single blade 22a, 22b,... Rotates by rotating the electrode shaft 21. Accordingly, since the electrolyte rises inside the hollow tube 100 while rotating in a spiral, gas (bubbles) is hardly generated inside the hollow tube 100, but the balance between the flowing current and the circulation rate of the electrolytic solution is balanced. When broken, gas is generated in the form of bubbles.

  When bubbles are generated, they are detected by the optical sensor 40, and are any one of an electrolysis voltage, a flow rate of circulating liquid, a rotation speed of an electrode (wing), a temperature in the air conditioning cover 16, a temperature of the liquid, and a pulling pressure of the liquid discharge chamber. Will be adjusted.

In the present invention, it is needless to say that an electrolytic solution similar to the conventional one (for example, an electrolytic solution comprising hydrofluoric acid, sulfuric acid, and water) is used as the electrolytic solution. The thickness polished here is 50 μm to 100 μm when the hollow tube is a high-speed accelerator. Furthermore, the voltage applied during polishing is around 15 V, the flowing current is about 20 A / dm ² , the rotation speed of the electrode is about 5 rpm, and the circulating flow rate of the electrolyte is 5 L / min.

  The electrode used in the present invention can be used not only for electrolytic polishing of niobium but also for electrolytic polishing of the inner surface of various metal tubes, and can be used not only for electrolytic polishing but also for electrolytic plating.

  As described above, according to the present invention, when gas is generated in the form of bubbles with the progress of electrolytic polishing inside the hollow tube, the bubbles are detected, and the electrolytic state, for example, the flowing current or the circulation of the electrolyte is detected. Since the amount is adjusted, the industrial applicability is very high because the hollow tube, particularly the inner surface of the hollowing used for the linear equalizer can be uniformly polished in a short time.

DESCRIPTION OF SYMBOLS 10 Base 11 Base 14 Liquid introduction chamber 17 Liquid extraction chamber 21 Electrode shaft 20 Electrode 21 Electrode shaft 22 Blade electrode 22a, 22b ... Single blade 23 Slit group 23a, 23b ... slit 29 Storage cylinder 40 Optical sensor 50 Control means 100 Cavity pipe 191 Circulation port 192 Circulation hose 194 Gas exhaust port

Claims (3)

In the electropolishing apparatus for electropolishing the inner surface of the hollow tube with an electrode inserted in the axial direction,
A liquid outlet chamber provided at an upper end of the hollow pipe and having a liquid circulation port at a predetermined height;
A liquid circulation means for injecting an electrolytic solution from the lower end of the hollow tube into the hollow tube, and further circulating the electrolytic solution from the hollow tube through the liquid circulation port of the liquid outlet chamber;
Bubble detecting means for detecting bubbles staying at a position above the water line near the liquid circulation port of the liquid outlet chamber;
Control means for receiving the output of the detection means to control the occurrence of bubbles;
An electrolytic polishing apparatus for a hollow tube, comprising:   2. The electrolytic polishing apparatus for a hollow tube according to claim 1, wherein the bubble detecting means is an optical sensor that detects transmission of light on the upper side of the water line of the liquid outlet chamber. The control object of the control means is at least one of the temperature in the air-conditioning cover enclosing the hollow tube, the temperature of the electrolytic solution, the pressure of the liquid outlet chamber, the circulating flow rate of the electrolytic solution, and the electrolytic voltage. Polishing device for hollow tube as described in

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