An electroforming core mold and a method for manufacturing a metal capillary using the same

Abstract

The patent of the present invention relates to the field of electrochemical processing, and provides an electroforming core mold and a method for manufacturing a metal capillary. The electroforming core mold is segmented to solve the problem of the difficulty in demolding the current electroforming capillary. The core mold is divided into five parts: a front end section, a groove section, a clamping section, an electroforming section, and a rear end section. Except for the electroforming section, all parts are covered with an electrical insulation layer. When in use, the core mold is still operated according to the traditional electroforming process. Due to the existence of the electrical insulation layer, only the electroforming section is covered with an electroforming metal layer. After electroforming, the core mold is cut at the groove section of the core mold to split the core mold into separate segment group units. The traditional long core mold overall demolding can be transformed into short core mold segmented demolding through segmented processing. Because a clamping section dedicated to demolding is provided, it is easier to apply tension to the core mold, and the fracture of the core mold is easier to control, thereby reducing the difficulty of demolding. The use of the present invention can simplify the demolding operation and improve the yield while ensuring the quality of the electroformed capillary.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical machining, and in particular relates to an electroforming core mold and a method for manufacturing a capillary tube using the core mold. Background Art

[0002] Metal capillaries with an inner diameter of less than several hundred microns have important uses in many industries and fields, such as chromatographic analysis tubes, automated instrument signal tubes, probe tubes for electronic testing, optical fiber connectors, injection needles, etc. At present, the manufacturing of metal capillaries mostly adopts drawing, stamping, hydrostatic extrusion, electroforming and other methods. Although drawing, stamping, hydrostatic extrusion and other methods have their own advantages, they all face common problems: (1) low thickness uniformity and low precision; (2) it is impossible to obtain capillaries with very small inner diameters; (3) due to the limitation of the forming principle, it is impossible to obtain capillaries with small inner diameters and large wall thicknesses. However, electroforming has great advantages in these aspects. Therefore, electroforming is the main method for manufacturing high-performance and high-precision metal capillaries.

[0003] Electroforming is a process of using the principle of cathode electrodeposition of metal ions to deposit a certain thickness of metal, alloy or composite material on the original mold, and then separate it from the original mold to produce a product. It is a precision special processing technology. Electroforming has the characteristics of high replication accuracy, pure materials, and easy performance control. It is particularly suitable for manufacturing metal capillaries with large wall thickness, high precision, high surface quality, and ultra-fine inner diameter. For example, the patent No. 200480042540.0 proposes an electroforming manufacturing method for metal capillaries. It is based on a long linear mandrel to electroform a long capillary blank at one time, and then cut and segment it to obtain the capillary of the final required length. Although the mandrel cost of this method is low, its demolding is extremely difficult. To some extent, it is relatively easy to prepare capillary blanks by electroforming. The biggest problem is: how to remove the mandrel from the metal blank tube after electroforming, that is, demolding. Demolding is the biggest technical challenge for electroforming metal capillaries. In this regard, patents No. 201680019698.9 and 201210095159.7 have proposed some demolding technical solutions, but the results are still not ideal. The main reasons are: (1) The bonding force between the metal capillary blank and the linear core mold increases linearly with their length, and the linear core mold is thin and can be easily broken by stretching, which makes it difficult to achieve overall demolding directly by mechanical stretching and the success rate is very low; (2) The chemical dissolution method is also ineffective because the corrosive liquid cannot overcome the surface tension and smoothly enter the deep inner diameter of the capillary to continuously dissolve and remove the core mold metal. If the difference in thermal expansion coefficient between metals is used to demold by thermal expansion and contraction, it is not feasible. The reason is: thermal expansion and contraction make it difficult to make the gap between the electroformed metal and the core mold metal large enough to be demolded smoothly, especially for the demolding of long metal capillaries. In addition, although the combination of "flexible non-metal or metal wire + transition metal layer" is used as the electroforming core mold, it is easy to stretch and demould, but the inner diameter accuracy of the capillary cannot be guaranteed. Therefore, the present invention proposes a new electroforming core mold and a method for electroforming a metal capillary using the core mold to achieve the purpose of easy demoulding and high product yield. Summary of the invention

[0004] Aiming at the shortcomings of the existing core mold and demoulding process used for electroforming capillaries, the present invention provides a core mold for electroforming metal capillaries, and adopts the core mold to achieve large-scale, high-efficiency and high-yield production of metal capillaries.

[0005] To achieve the above object, the technical solution of the present invention is as follows.

[0006] An electroforming core mold comprises a metal wire and an electrical insulation layer; the wire is provided with a clamping section, a groove section, an electroforming section, a front end section and a rear end section; the groove section, the clamping section and the electroforming section are arranged on the wire in sections to form a plurality of section group units; the section group unit comprises two groove sections, two clamping sections and one electroforming section; the sections in the section group unit are arranged in the order of the groove section, the clamping section, the electroforming section, the clamping section and the groove section; the front end section and the rear end section are respectively located at the two ends of the wire; the outer surfaces of the front end section, the rear end section, the groove section and the clamping section are all covered with an electrical insulation layer; the outer surface of the middle part of the electroforming section is covered with an electrical insulation layer, and the length of the covered part is 4 / 5 of the length of the electroforming section; the cross-sectional shape of the wire is circular; the diameter Da of the groove section is 1.5 to 2 times the diameter Dz of the electroforming section; the diameter Dj of the clamping section is 2 to 3 times the diameter Dz of the electroforming section; the diameters of the clamping section, the front end section and the rear end section are equal.

[0007] The material of the wire of the core mold is SUS304 stainless steel. This material has the characteristics of corrosion resistance, good toughness, and weak bonding force of electroformed metal, which is conducive to stretching and demoulding.

[0008] The length Lj of the clamping section of the core mold is 10-20 mm. The clamping section is set to reserve the necessary length when the clamp is clamped.

[0009] The length La of the groove section of the core mold is 1-2 mm. This is the division point of the segment group unit.

[0010] The length Lq of the front end section of the core mold is equal to the length Lh of the rear end section, which is 20-30 mm. The front end section and the rear end section are arranged to ensure that the core mold can be conveniently clamped and fixed during electroforming.

[0011] The diameter Dz of the electroforming section of the core mold is 50-1000 μm.

[0012] The number of segment group units of the core mold is greater than 2.

[0013] The material of the electrical insulation layer of the core mold is acid and alkali corrosion resistant material, and its thickness is 10nm~5μm. The electrical insulation layer is to prevent the electroforming of the metal layer on the outer surface (non-electroforming metal area) of the front end section, the rear end section, the groove section, and the clamping section, so as to obtain the desired capillary shape. The acid and alkali corrosion resistant material is used to prevent the electrical insulation layer from reacting with the electroforming liquid during the electroforming process, contaminating the electroforming liquid and causing electroforming failure.

[0014] A method for manufacturing a metal capillary, characterized in that it comprises the following steps:

[0015] (1) After pre-treating the core mold according to the electroforming process specifications, place the core mold in the electroforming solution tank;

[0016] (2) electroforming a metal layer onto the core mold using the core mold as a cathode;

[0017] (3) When the outer diameter of the metal layer at the electroforming section reaches the requirement, the electroforming is stopped. At this time, the metal layer forms a capillary tube blank. The core mold with the capillary tube blank is taken out of the electroforming tank liquid, cleaned and dried;

[0018] (4) cutting off each groove segment of the core mold to divide the core mold into a plurality of segment group units;

[0019] (5) Using the clamping section as the clamping section, the segment group unit is precisely stretched until the electroformed segment in the segment group unit is broken;

[0020] (6) removing the broken electroformed section from the capillary tube blank;

[0021] (7) Cutting and polishing the two ends of the capillary tube blank to finally obtain a metal capillary;

[0022] (8) Repeat steps (4) to (7) to process other segment group units until all segment group units have been processed.

[0023] Compared with the prior art, the main advantages of the present invention are: while ensuring the quality of the electroformed capillary, it greatly simplifies the demoulding operation and has a high yield. This patent is based on the new idea of ​​"segmented electroforming and segmented demoulding", replacing the traditional practice of "first overall electroforming and then cutting into segments" in the field, making demoulding very easy and greatly improving the yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the core mold segment unit.

[0025] Figure 2 It is a schematic diagram of the core mold (2 segment group units).

[0026] Figure 3 This is a schematic diagram of the core mold electroforming process.

[0027] Figure 4 It is a schematic diagram of the segment unit after electroforming.

[0028] Figure 5 It is a stretching diagram.

[0029] Figure 6 It is a schematic diagram of a capillary tube blank.

[0030] Figure 7 It is a schematic diagram of cutting a capillary tube blank.

[0031] Figure 8 is a schematic diagram of a capillary tube.

[0032] Numbers and names in the figure: 1, metal wire; 2, electrical insulation layer; 3, clamping section; 4, groove section; 5, electroforming section; 6, segment group unit; 7, front end section; 8, rear end section; 9, electroforming layer; 10, clamp; 11, capillary tube blank; 12, capillary; 13, end of capillary tube blank; b, thickness of electrical insulation layer; Lj, clamping section length; La, groove section length; Lq, front end section length; Lh, rear end section length; Dz, electroforming section diameter; Dj, clamping section diameter; Da, groove section diameter; Dq, front end section diameter; Dh, rear end section diameter; D, capillary diameter. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings.

[0034] The core mold of the present invention is as follows Figure 1 and Figure 2 As shown, the filament is provided with a clamping section 3, a groove section 4, an electroforming section 5, a front end section 7 and a rear end section 8; the groove section 4, the clamping section 3, and the electroforming section 5 are arranged in sections on the filament 1 to form a plurality of section group units 6; the section group unit 6 includes two groove sections 4, two clamping sections 3 and one electroforming section 5; the sections in the section group unit are arranged in the order of the groove section 4, the clamping section 3, the electroforming section 5, the clamping section 3, and the groove section 4; the front end section 7 and the rear end section 8 are respectively located at the two ends of the filament 1; the front end section 7, the rear end section 8 The outer surfaces of the segment 8, the groove segment 4 and the clamping segment 3 are all covered with an electrical insulating layer 2, and the material of the electrical insulating layer 2 is corrosion-resistant insulating paint; the outer surface of the middle part of the electroformed segment 5 is covered with an electrical insulating layer 2, and the length of the covered part is 4 / 5 of the length of the electroformed segment 5; the cross-sectional shape of the filament 1 is circular; the diameter Da of the groove segment 4 is 1.5 times the diameter Dz of the electroformed segment 5; the diameter Dj of the clamping segment 3 is 2.5 times the diameter Dz of the electroformed segment 5; the diameters of the clamping segment 3, the front end segment 7 and the rear end segment 8 are equal.

[0035] The main steps of electroforming metal capillary based on the above core mold are as follows:

[0036] (1) A core mold consisting of two segment group units 6 is selected, wherein the length Lj of the clamping segment 3 is 15 mm, the length La of the groove segment 4 is 2 mm, the lengths Lq and Lh of the front segment 7 and the rear segment 8 are 25 mm, the diameter Dz of the electroformed segment 5 is 150 μm, the material of the electrical insulation layer 2 is corrosion-resistant insulating paint, the thickness b is 5 μm, the length of the covered portion of the electrical insulation layer 2 is 4 / 5 of the length of the electroformed segment 5, the diameter Da of the groove segment 4 is 1.5 times the diameter Dz of the electroformed segment 5, and the diameter Dj of the clamping segment 3 is 2.5 times the diameter Dz of the electroformed segment 5;

[0037] (2) Surface finishing, oil removal and rust removal of the core mold;

[0038] (3) The treated core mold is weakly etched in a 120 mL / L sulfuric acid solution at room temperature for 4 minutes, then passivated in a 20 g / L potassium dichromate solution at room temperature for 15 minutes, then taken out, rinsed with running cold water and dried;

[0039] (4) placing the dried core mold into an electroforming device as a cathode, with the anode material being electrolytic nickel;

[0040] (5) Add the prepared electroforming solution into the electroforming device. The electroforming solution is a mixed solution of nickel sulfamate (300 g / L), nickel chloride (10 g / L), and boric acid (35 g / L). 2 The electroforming was performed at a current density of , during which the solution temperature was maintained at 55°C, the pH was 4, the solution was stirred mechanically, and the electroforming lasted for 6 hours. The thickness of the capillary tube blank 11 obtained thereafter was 55 μm. When the electroforming was completed, the core mold with the capillary tube blank 11 was taken out, rinsed with clean water, and dried;

[0041] (6) cutting off each groove segment 4 of the core mold to obtain two segment group units 6 with an electroformed layer 9;

[0042] (7) Clamp the clamping segment 3 with the fixture 10 of the precision electronic tensile machine, and stretch the segment group unit 6 with a force increment of 1N until the electroformed segment 5 is broken;

[0043] (8) taking out the broken mandrel to obtain the capillary tube blank 11 separated from the electroforming section 5;

[0044] (9) Cutting both ends of the capillary tube blank 11 and polishing and finishing the cut portions to obtain a metal capillary tube 12;

[0045] (10) Repeat steps (7) to (9) to process another segment unit to obtain a second metal capillary 12.

Claims

1. A method for manufacturing a metal capillary, characterized in that: The following steps are involved: (1) After pre-treating the core mold according to the electroforming process specifications, place the core mold in the electroforming solution tank; (2) electroforming a metal layer (9) onto the core mold using the core mold as a cathode; (3) When the outer diameter of the metal layer (9) at the electroforming section (5) reaches the required value, the electroforming is stopped. At this time, the metal layer (9) forms a capillary tube blank (11). The core mold with the capillary tube blank (11) is taken out from the electroforming tank liquid, cleaned and dried; (4) cutting off each groove segment (4) of the core mold to divide the core mold into a plurality of segment group units (6); (5) Using the clamping section (3) as the clamping section, the segment group unit (6) is precisely stretched until the electroformed segment in the segment group unit (6) is broken; (6) removing the broken electroformed section (5) from the capillary tube blank (11); (7) Cutting and polishing the two ends of the capillary tube blank (11) to finally obtain a metal capillary tube (12); (8) Repeat steps (4) to (7) to process other segment group units (6) until all segment group units (6) are processed; The core mold is an electroforming core mold; The electroforming core mold is characterized in that: it comprises a metal wire (1) and an electrical insulating layer (2); the wire is provided with a clamping section (3), a groove section (4), an electroforming section (5), a front end section (7) and a rear end section (8); the groove section (4), the clamping section (3) and the electroforming section (5) are arranged on the wire (1) in a group to form a plurality of section group units (6); the section group unit (6) comprises two groove sections (4), two clamping sections (3) and one electroforming section (5); each section in the section group unit is arranged according to the groove section (4), the clamping section (3) and the electroforming section (5); The holding section (3), the electroforming section (5), the clamping section (3), and the groove section (4) are arranged in sequence; the front end section (7) and the rear end section (8) are respectively located at the two ends of the filament (1); the outer surfaces of the front end section (7), the rear end section (8), the groove section (4), and the clamping section (3) are all covered with an electrical insulating layer (2); the outer surface of the middle part of the electroforming section (5) is covered with an electrical insulating layer (2), and the length of the covered part is 4 / 5 of the length of the electroforming section (5); the cross-sectional shape of the filament (1) is circular; the diameter d of the groove section (4) is 凹 is the diameter d of the electroforming section (5) 铸 1.5 to 2 times the diameter of the clamping section (3); 夹 is the diameter d of the electroforming section (5) 铸 2 to 3 times of the diameter of the clamping section (3), the front end section (7) and the rear end section (8) are equal.

2. A method for manufacturing a metal capillary according to claim 1, characterized in that: The material of the filament (1) is SUS304 stainless steel.

3. A method for manufacturing a metal capillary according to claim 1, characterized in that: The length L of the clamping section (3) is 夹 It is 10~20mm.

4. A method for manufacturing a metal capillary according to claim 1, characterized in that: The length L of the groove section (4) is 凹 1~2mm.

5. The method for manufacturing a metal capillary according to claim 1, characterized in that: The length L of the front end section (7) is 前 and the length L of the rear end section (8) 后 The diameter of the two plates is equal, both are 20~30mm.

6. A method for manufacturing a metal capillary according to claim 1, characterized in that: The diameter d of the electroforming section 铸 50~1000μm.

7. A method for manufacturing a metal capillary according to claim 1, characterized in that: The number of the segment group units (6) is greater than 2.

8. The method for manufacturing a metal capillary according to claim 1, characterized in that: The electrical insulation layer (2) is made of a material resistant to acid and alkali corrosion and has a thickness of 10 nm to 5 μm.

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