Anode hanger for electroforming square capillaries

Abstract

The invention belongs to the field of electroforming, and particularly relates to an anode hanger for electroforming square capillary tubes, which comprises a square metal core mold, four sheet-shaped anodes, four shielding plates, an anode fixing seat, an anode guide seat, two electrically-conductive titanium sheets and a hanging rod. The anode fixing seat is provided with a square through hole. The anode guide seat is provided with a square through hole and a square groove. Flexible bristles are arranged on the wall surface of the square through hole II. The two electrically-conductive titanium sheets are provided with a square through hole III, which are in close contact with and electrically connected to the front and back end surfaces of the sheet-shaped anode. The center lines of the cross sections of the square through hole I, the square through hole and the square through hole III are collinear, and the three are non-contact and reciprocally linearly movable on the square metal core mold. The invention can effectively solve the problems of rounding of the outer surface and poor thickness uniformity of the electroformed square capillary tube, and ensure high-precision forming of the square capillary tube.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of micro electroforming, and particularly relates to an anode hanger for electroforming square capillary. BACKGROUND

[0002] Capillary tubes with inner diameter features in the micron and sub-millimeter levels are widely used in electrical and electronic, optical, chemical detection, medical and other fields, such as semiconductor probe sleeves, optical fiber pins, heart stent guide tubes, etc. Among them, the special-shaped tube with square cross-sectional features (referred to as square capillary) is suitable for electric spark machining electrodes, micro heat exchange channels, etc. due to its unique structure and functional utility. The existing square capillary processing technologies mainly include mechanical drawing, rolling forming, hydraulic forming, electroforming processing, etc. Among them, electroforming processing has unique pipe manufacturing technology advantages such as high forming precision, small inner hole diameter forming capability, high inner profile forming quality, and the ability to realize the independence of inner hole diameter and pipe wall thickness. It is the first choice for ultra-smooth inner hole wall surface, ultra-fine inner diameter, large wall thickness, and high-precision capillary metal pipe manufacturing technology. Since the electroforming manufacturing of capillary tubes is to realize the precise forming of the inner hole of the capillary tube by copying the geometric shape features of the core mold, the key of this technology is to control the forming precision of the wall thickness or the outer diameter, that is, the uniformity of the wall thickness distribution (including radial / circumferential and axial). Canadian patent No. CA2351326 discloses a device for electroforming manufacturing of metal capillary tubes with circular cross-section. It adopts a vertical four-corner distributed remote anode mode to achieve better radial thickness uniformity than single anode. Japanese patent WO2006135057A1 introduces a capillary tube electroforming device which adopts a horizontal rotating cathode mode to improve the circumferential distribution uniformity of the wall thickness of the circular cross-section capillary tube. However, in addition to the common uniformity problem of circular cross-section capillary tubes, square cross-section capillary tubes also have the problem of individual forming. The edge corners of the square cross-section core mold have more concentrated current density distribution due to the sharp end discharge effect, which causes the metal growth rate at this place to be significantly faster than other places. Under normal circumstances, this inevitably causes the cross-section of the finally formed capillary tube to have problems such as edge corner rounding and uneven wall thickness distribution, resulting in poor forming precision, and the thicker the wall, the more serious the above-mentioned phenomenon. Obviously, the existing technical solutions for electroforming of circular cross-section capillary tubes are difficult to be applied to the electroforming of square cross-section capillary tubes. Based on this, the present application discards the previous electroforming modes such as remote anode and rotating cathode, and designs and develops an anode hanger for electroforming square capillary tubes to realize high-precision forming of square capillary tubes. SUMMARY

[0003] The purpose of the present application is to solve the problems of cross-section edge corner rounding and poor thickness uniformity in electroforming square capillary tubes, and to ensure high-precision forming of square capillary tubes.

[0004] The technical scheme of the present application is: a kind of anodic hanger for electroforming square capillary, including square metal core mould, it further includes four sheet anode, four shielding plates, anode fixing seat, anode guide base, two electrically conductive titanium sheets, hanging rod;The square through hole is equipped on the anode fixing seat ;The geometric shape and size of the four sheet anodes are same, and are fixed to the four peripheral sidewalls of square through hole , and the outer surface of sheet anode is flush with the sidewall surface of square through hole I;The four shielding plates are fixed at the four corners of square through hole , and the width of each shielding plate extending outward is adjustable along diagonal direction, and the use of shielding plate can effectively avoid the concentration of electric field at the corner of square metal core mould;The square through hole II is equipped on the anode guide base , square recess;The anode fixing seat is fixed in square recess;The peripheral wall surface of square through hole II is equipped with flexible bristles, which can enhance stirring while playing the role of electric field shielding, avoiding the radiation of electric field into square through hole , and improving the axial uniformity of electroforming;The two electrically conductive titanium sheets are equipped with square through hole III;The two electrically conductive titanium sheets are in close contact with the front and rear end surfaces of sheet anode and are electrically connected;The hanging rod is detachably and sealingly connected with anode fixing seat and anode guide base;The center lines of the cross sections of square through hole I, square through hole And square through hole are collinear, and they are all non-contact, reciprocating and linearly movable on square metal core mould.

[0005] The sheet anode is made of titanium or platinum. The use of insoluble anode can avoid frequent replacement of anode.

[0006] The width w1 of sheet anode is 75%~80% of the cross section side length w2 of square metal core mould. This is to weaken the influence of edge effect and further uniform the electric field distribution on the cross section of square metal core mould.

[0007] The thickness h of shielding plate is 10%~20% of the cross section side length w2 of square metal core mould.

[0008] The side length w3 of square through hole Is 3~5 times of the cross section side length w2 of square metal core mould.

[0009] The distance w4 between cross section corner point of square metal core mould and shielding plate extending end is 100 μm~200 μm.

[0010] The material of shielding plate, anode fixing seat, anode guide base and hanging rod is electrically insulating polypropylene.

[0011] The material of the flexible brush is electrically insulating polypropylene.

[0012] Compared with the prior art, the present application has the following beneficial effects.

[0013] (1) The uniformity of the wall thickness distribution of the square capillary cross section is greatly improved. The thin sheet-shaped anode placed close to the side wall of the square metal core mold greatly reduces the tip concentration effect at the corners, and the electric field lines are more uniformly distributed along the cross section. The patent further blocks the concentration of electric field lines at the corners by adding shielding plates, and the combination of the two greatly improves the uniformity of the electric field line distribution along the cross section. Under the condition of reasonably optimizing their sizes, the use of the two in combination can achieve uniform electric field distribution along the cross section of the square metal core mold. At the same time, the present application uses a reciprocating deposition method and a flexible brush to enhance mass transfer and ensure good mass transfer conditions. In summary, the present application can obtain a square metal capillary with greatly improved uniformity of cross-sectional thickness distribution.

[0014] (2) The axial thickness distribution uniformity of the square capillary is greatly improved. The use of flexible brush plays a role in electric field shielding, improving the localization of electric field distribution along the axial direction of the square metal core mold, and avoiding the radiation of electric field into the square through hole; the reciprocating deposition method further enhances the axial thickness uniformity of the electroformed layer. This greatly improves the problem of "thick at both ends and thin in the middle" existing in conventional electroforming, and improves the axial thickness distribution uniformity.

[0015] (3) The radius of the arc at the corner of the square capillary is greatly reduced. The electric field shielding and edge effect at the corner of the square metal core mold cross section greatly improve the uniformity of the electric field distribution of the square metal core mold cross section, avoid the concentration of electric field at the corner of the square metal core mold cross section, and effectively reduce the radius of the arc at the corner of the square capillary.

[0016] (4) The mass transfer conditions are improved, and the outer surface quality of the square capillary is greatly improved. The present application uses a reciprocating deposition method to strengthen the replenishment of fresh electrolyte on the surface of the square metal core mold, which is beneficial to the release of hydrogen bubbles on the surface of the square metal core mold; the present application uses a flexible brush to enhance stirring and remove hydrogen bubbles to ensure good mass transfer conditions. In summary, under the condition of uniform electric field distribution, the mass transfer conditions on the surface of the square metal core mold are good, and the outer surface quality of the square capillary can be greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic diagram of an anode hanger for electroforming a square capillary.

[0018] ​Figure 2 This is a schematic diagram of the anode guide seat.

[0019] Figure 3 This is a schematic diagram of an electrostatically charged titanium sheet.

[0020] Figure 4 This is a schematic diagram of electrolyte flow and electric field lines distribution along the axial direction of the square metal core mold.

[0021] Figure 5 This is a schematic diagram of the electric field line distribution across the cross-section of the square metal core mold of this invention.

[0022] Figure 6 This is a schematic diagram of the electric field line distribution across the cross-section of a square metal core mold without a shielding plate.

[0023] In the diagram: 1. Electrolyte; 2. Square metal core mold; 3. Thin-film anode; 4. Shielding plate; 5. Anode holder; 5-1. Square through hole 6. Anode guide seat; 6-1. Square through hole 6-1-1 Flexible bristles; 6-2 Square groove; 7. Electrostatically charged titanium sheet; 7-1 Square through hole 8. Hanging rod; 9. Power supply; w1. Width of the sheet anode; w2. Side length of the cross-section of the square metal core mold; w3. Square through hole The side length of the shielding plate; w4, the distance between the corner points of the cross-section of the square metal core mold and the extended end of the shielding plate; h, the thickness of the shielding plate. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings.

[0025] The square metal core mold 2 has a cross-sectional side length w2 of 0.8 mm and a length of 10 mm, and is made of aluminum. The purpose of this specific example is to use the square metal core mold 2 to electroform a square metal capillary with a cross-sectional side length of 1 mm, a wall thickness of 0.1 mm, and a length of 10 mm, made of copper. Figures 1-5 As shown, an anode holder for an electroformed square capillary includes a square metal core mold 2, four thin-plate anodes 3, four shielding plates 4, an anode fixing seat 5, an anode guide seat 6, two electrostatic titanium sheets 7, and a hanging rod 8; the anode fixing seat 5 is provided with a square through hole. 5-1; Four thin-plate anodes 3 have the same geometry and size, and are fixed to square through holes respectively. The four sides of hole 5-1, and the outer surface of each of the thin sheet anodes 3 are flush with the side wall surface of the square through hole I5-1; four shielding plates 4 are respectively fixed to the square through hole. The width of the extension of the shielding plate 4 at the four corners of the square is adjustable along the diagonal direction; and the anode guide seat 6 is provided with a square through hole 6-1, square groove 6-2; the anode fixing seat 5 is matched and fixed in the square groove 6-2; the square through hole II 6-1 is provided with flexible bristles 6-1-1 at each position of the wall surface; 2 electrically-conductive titanium sheets 7 are provided with a square through hole III 7-1, which are in close contact with and electrically connected with the front and rear end surfaces of the sheet-shaped anode 3 respectively; the hanging rod 8 is detachably and sealingly connected with the anode fixing seat 5 and the anode guide seat 6; the square through hole I 5-1, the square through hole 6-1 and the square through hole 7-1 are coaxial in the cross section center line, and are non-contact and reciprocating linearly movably sleeved on the square metal core mold 2.

[0026] The sheet-shaped anode 3 is made of titanium, the width w1 of the sheet-shaped anode 3 is 0.65 mm; the thickness h of the shielding plate 4 is 0.1 mm; the square through hole 5-1 has a side length w3 of 4 mm; the spacing w4 between the square metal core mold 2 and the extension end of the shielding plate 4 is 200 μm.

[0027] The materials of the shielding plate 4, the anode fixing seat 5, the anode guide seat 6 and the hanging rod 8 are electrically-insulating polypropylene; the material of the flexible bristles 6-1-1 is electrically-insulating polypropylene.

[0028] After the power supply 9 is started, the anode hanger of the square capillary used for electroforming moves along the square metal core mold 2 in the axial reciprocating movement. When moving to the left, the flow of the electrolyte 1 and the axial electric field line distribution are as shown in Figure 4 After the electrolyte 1 is stirred by the flexible bristles 6-1-1, it flows into the interior of the square through hole 5-1, the hydrogen bubbles adhered to the square metal core mold 2 are taken away by the flexible bristles 6-1-1, the mass transfer is enhanced, and the deposition quality is improved. At the same time, the flexible bristles 6-1-1 hinder the distribution of the electric field lines, avoid the distribution of the electric field lines in the square through hole II 6-1, and improve the axial electroforming uniformity.

[0029] The cross section electric field line distribution of the square metal core mold 2 of the present application is as shown in Figure 5 The electric field lines are hindered by the shielding plate 4, and the influence of the sharp tip discharge is weakened. As shown in Figure 6 The cross section electric field line distribution of the square metal core mold 2 without the shielding plate 4 is as shown in

[0030] After the thickness of the electroforming layer reaches 0.1 mm, the electroforming is stopped. After the square metal capillary is obtained by chemically dissolving and removing the aluminum square metal core mold 2 of the square metal capillary with the aluminum square metal core mold 2.

[0031] The above description illustrates the technical field, main technical features, solved technical problems, beneficial effects and specific implementation modes of the present application. The present application is not limited by the specific drawings, the present application is not limited by the specific implementation modes, various changes, improvements and extensions of the present application can be made without departing from the spirit and scope of the present application, and these changes, improvements and extensions all fall within the scope of the present application claimed, the scope of the present application claimed is defined by the appended claims and their equivalents.

Claims

1. An anode fixture for electroforming square capillary tubes, comprising a square metal core mold (2), characterized in that: It also includes 4 thin-plate anodes (3), 4 shielding plates (4), anode fixing base (5), anode guide base (6), 2 lead-in titanium plates (7), and hanging rod (8); the anode fixing base (5) is provided with a square through hole I (5-1); the 4 thin-plate anodes (3) have the same geometry and size, and are respectively fixed to the four sides of the square through hole I (5-1), and the outer surface of each thin-plate anode (3) is flush with the side wall of the square through hole I (5-1); the 4 shielding plates (4) are respectively fixed at the four corners of the square through hole I (5-1), and the width of each shielding plate (4) extending outward is adjustable along the diagonal direction; the anode guide base (6) is provided with a square through hole II (6-1) and a square groove. (6-2); the anode fixing seat (5) is fixed in the square groove (6-2); the four sides of the square through hole II (6-1) are provided with flexible bristles (6-1-1); the two electrostatic titanium sheets (7) are provided with square through holes III (7-1); the two electrostatic titanium sheets (7) are in close contact with the front and rear ends of the sheet anode (3) and electrically connected; the hanging rod (8) is detachably sealed to the anode fixing seat (5) and the anode guide seat (6); the cross-sectional center lines of the square through holes I (5-1), square through holes II (6-1) and square through holes III (7-1) are collinear, and they are all non-contactly and reciprocally linearly mounted on the square metal core mold (2).

2. The anode hanger for electroformed square capillary tubes according to claim 1, characterized in that: The sheet-like anode (3) is made of titanium or platinum.

3. The anode hanger for electroformed square capillary tubes according to claim 1, characterized in that: The width w1 of the sheet-like anode (3) is 75% to 80% of the side length w2 of the cross-section of the square metal core mold (2).

4. The anode hanger for electroformed square capillary tubes according to claim 1, characterized in that: The thickness h of the shielding plate (4) is 10% to 20% of the side length w2 of the cross section of the square metal core mold (2).

5. The anode hanger for electroformed square capillary tubes according to claim 1, characterized in that: The side length w3 of the square through hole I (5-1) is 3 to 5 times the side length w2 of the cross section of the square metal core mold (2).

6. The anode hanger for electroformed square capillary tubes according to claim 1, characterized in that: The distance w4 between the corner points of the cross section of the square metal core mold (2) and the extended end of the shielding plate (4) is 100μm~200μm.

7. The anode hanger for electroformed square capillary tubes according to claim 1, characterized in that: The shielding plate (4), anode fixing seat (5), anode guide seat (6), and hanging rod (8) are all made of electrically insulating polypropylene.

8. The anode hanger for electroformed square capillary tubes according to claim 1, characterized in that: The flexible bristles (6-1-1) are made of electrically insulating polypropylene.

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