Patent Publication Number: US-2006011481-A1

Title: Method for manufacturing multi-core metal pipe by electroforming

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates to a method for manufacturing a multi-core metal pipe in which a plurality of thin holes are arranged with high precision by electroforming, the method used for a multi-core ferrule such as a connector for an optical fiber and a device, a nozzle of an injection pump for an engine, and a nozzle of an ink-jet printer or the like.  
     DESCRIPTION OF THE INVENTION  
      The present applicants have invented a method for manufacturing a multi-core metal pipe in which a plurality of thin holes are arranged with high precision by electroforming, the method used for a multi-core ferrule such as a connector for an optical fiber and a device, and have applied as Japanese Patent Application No. 2002-281957, “METHOD FOR MANUFACTURING MULTI-CORE METAL PIPE SUCH AS MULTI-CORE FERRULE FOR OPTICAL CONNECTOR BY ELECTROFORMING” on Aug. 15, 2002. This method manufactures the multi-core metal pipe such as the multi-core ferrule for the optical fiber as follows. One obtained by stretching a plurality of wire materials such as metal and plastic is used as a mother die, and the wire material is removed after electroforming. The hole positions of a plurality of electrical isolation plates in which a plurality of holes having an exact diameter are opened at exact positions and which have the same shape are arranged on a straight line. A cathode jig composed by inserting wire materials into the plurality of holes of the electrical isolation plate in a straight line in parallel without twisting the wire materials is immersed into an electroforming liquid. A minus energization is performed to only the wire material provided near the center and having electrical conductivity to electroform. Furthermore, so as to make the outer shape of the metal pipe formed by electroforming circular, a distance between the wire material located at the center of the cathode jig and the anode is set almost the same distance, and the electroforming is performed while rotating with the wire material of the cathode jig at almost the center.  
      Examples of known methods for manufacturing the metal pipe such as the ferrule for the optical connector and a sleeve by electroforming include “METHOD FOR MANUFACTURING METAL PIPE” in Japanese Published Unexamined Patent Application No. 2003-313695.  
     SUMMARY OF THE INVENTION  
      So as to eliminate the misalignment of the holes due to the rotation of the cathode jig, the present invention adopts a method for manufacturing a multi-core metal pipe by electroforming, comprising the steps of: immersing a cathode jig formed by stretching a plurality of wire materials  5  to insulating plates as a pair of electrical isolation supports in an electroforming liquid, at least one of the wire materials composed by a conductive material; arranging an anode outside the cathode jig in the electroforming liquid; energizing a direct current between the conductive wire material of the cathode jig and the anode to produce a metal pipe with the conductive wire material as the axial center; and withdrawing the plurality of wire materials to manufacture the metal pipe, wherein the anode is revolved with the conductive wire material as a rotation axis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a front view obtained by crossing longitudinally a part of an electroforming device used for a first embodiment of the present invention.  
       FIG. 2  is a plan view showing an essential part of  FIG. 1 .  
       FIG. 3  is a front view obtained by crossing longitudinally a part of an electroforming device used for a second embodiment of the present invention.  
       FIG. 4  is a plan view showing an essential part of  FIG. 3 . 
    
    
      Numerals expressed by numbers are as follows. 
       1 ; electroforming liquid tank      2 ; cathode jig      3 ,  4 ; insulating plate      5 ; wire material      6 ; stationary plate      7 ; tensile coil spring      8 ; stationary plate      9 ; disc      11  to  14 ; guide pulley      15  to  17 ; anode      18 ; idler      19 ; motor      21 ; output shaft roller      22 ; brush      23 ; control tank      24 ; filter      31 ; internal cylinder      32 ; external cylinder      33 ; anode      34  to  37 ; stay    

     Embodiment  
      With reference to the figures, embodiments of the present invention will be described.  
       FIG. 1  is a front view obtained by crossing longitudinally a part of an electroforming device used for a first embodiment of the present invention.  FIG. 2  is a plan view showing an essential part of  FIG. 1 . In  FIG. 1 , numeral  1  designates an electroforming liquid tank which is filled with an electroforming liquid to the edge part, and a cathode jig is arranged in the vertical direction at the center thereof. Referring to the cathode jig, a plurality of holes for inserting wire materials are punched at the same positions of insulating plates as an electrical isolation support, and the insulating plates are supported at prescribed intervals in the vertical direction. A stainless steel wire material having electrical conductivity is inserted and stretched into the punched hole of the central position. Since the electrical conductivity is not considered for the remaining holes, resin wire materials or metal wire materials having a surface on which a resin is coated are inserted and stretched into the remaining holes. The lower ends of the wire materials are connected to a stationary plate, and the upper ends are connected to a stationary plate composed of a conductive material via a tensile coil spring. Thereby, a moderate tension is given to the wire materials between the insulating plates.  
      A ring-shaped disc is rotatably supported by guide pulleys arranged at four corners with a stainless steel wire material of the cathode jig as a center above the liquid surface of the electroforming liquid tank. The disc is formed of the conductive material, and bottomed cylindrical anodes composed by a titanium net are attached to the lower surface of the disc are arranged at approximately equal intervals. In the anode, nickel grains or sticks are stored as an electroforming metal material. An output shaft roller of a motor with a reduction gear is abutted against the outer periphery of the disc via an idler. When the motor is rotated and driven, the rotation of the output shaft roller rotates and drives the disc via the idler. Thereby, the anode revolves around the cathode jig  2  with the stainless steel wire material of the cathode jig as the center.  
      A brush is slidably abutted against the right end part of the disc. A control tank set at the right of the electroforming liquid tank  1  of  FIG. 1  is connected to the electroforming liquid tank via a piping (not shown), and controls the concentration, specific gravity, temperature and level or the like of the electroforming liquid in the electroforming liquid tank so that they are kept constant. A filter set at the right of the control tank is connected to the control tank via a piping (not shown), and filters impurities generated in the electroforming liquid.  
      In the electroforming device constituted thus, when the motor is rotated and driven while a current is passed by connecting the stationary plate to a minus pole and connecting a plus pole to the brush, nickel of electroforming metal is deposited on the stainless steel wire material located at the center of the cathode jig. Thereby, a metal pipe having an outer shape perfectly round is generated with the stainless steel wire material as the central axis. This is because that the anode revolves on a circular orbit around the cathode jig at a fixed speed, and thereby referring to the deposit of the electroforming metal, an equivalent electric field is accumulated with a lapse of time, and nickel having an equivalent thickness is deposited on the whole periphery with the stainless steel wire material of the cathode jig as the center.  
      When the metal pipe grows to a predetermined thickness, the energization and the rotation of the anode are stopped. The metal pipe is then taken out from the cathode jig, and the stainless steel wire material and the resin wire material are extracted from the metal pipe. Thereby, a multi-core metal pipe in which a plurality of thin holes are arranged with high precision can be obtained. Since the outer shape of the obtained metal pipe is perfectly round, an after-treatment thereof can easily be performed. Since the cathode jig is stopped without rotating in the electroforming liquid in the method described above, the resin wire material arranged outside the stainless steel wire material of the center, or the metal wire material having the surface on which the resin is coated also stands still in the electroforming liquid, and the misalignment of the position of the wire material, that is, the misalignment of the position of the hole is eliminated. Though the three anodes are arranged in the shown example, the number of the anodes can be set to one or two, and the number can be set to four or more.  
       FIG. 3  is a front view obtained by crossing longitudinally a part of an electroforming device used for a second embodiment of the present invention.  FIG. 4  is a plan view showing an essential part of  FIG. 3 . In  FIG. 3 , numeral  1  designates an electroforming liquid tank which is filled with an electroforming liquid to the edge part, and a cathode jig is arranged in the vertical direction at the center thereof. Referring to the cathode jig, a plurality of holes for inserting wire materials are punched at the same positions of insulating plates as an electrical isolation support, and the insulating plates are supported at prescribed intervals in the vertical direction. A stainless steel wire material having electrical conductivity is inserted and stretched into the punched hole of the central position. Since the electrical conductivity is not considered for the remaining holes, resin wire materials or metal wire materials having a surface on which a resin is coated are inserted and stretched into the remaining holes. The lower ends of the wire materials are connected to a stationary plate, and the upper ends are connected to a stationary plate composed of a conductive material via a tensile coil spring. Thereby, a moderate tension is given to the wire materials between the insulating plates.  
      An anode having a double structure having an internal cylinder and external cylinder both composed of a titanium net is arranged outside the cathode jig of the electroforming liquid tank. Nickel grains or sticks are stored as the electroforming metal material between the internal cylinder and the external cylinder. Since four places of the upper end of the anode are supported to the edge of the electroforming liquid tank by stays, the inner surface of the internal cylinder is correctly held so as to be located above perfectly round with the stainless steel wire material of the cathode jig as the center.  
      A control tank set at the right of the electroforming liquid tank of  FIG. 3  is connected to the electroforming liquid tank via a piping (not shown), and controls the concentration, specific gravity, temperature and level or the like of the electroforming liquid in the electroforming liquid tank so that they are kept constant. A filter set on the right of the control tank is connected to the control tank via a piping (not shown), and filters impurities generated in the electroforming liquid.  
      In the electroforming device constituted thus, the current is passed by connecting the stationary plate to the minus pole, connecting the plus pole to the anode, and thereby nickel of the electroforming metal is deposited on the stainless steel wire material of the cathode jig, and the metal pipe having an outer shape perfectly round is generated with the stainless steel wire material as the central axis. This is because that since the inner surface of the internal cylinder of the anode is held at the position of perfectly roundness to the stainless steel wire material located at the center of the cathode jig, a uniform electric field is formed in the direction of the whole periphery of the stainless steel wire material of the cathode jig, and the electroforming metal is evenly deposited.  
      When the metal pipe grows to a predetermined thickness, the energization is stopped. The metal pipe is taken out from the cathode jig, and the stainless steel wire material and the resin wire material, or the metal wire material having the surface on which the resin is coated are extracted from the metal pipe. Thereby, a multi-core metal pipe in which a plurality of thin holes are arranged with high precision can be obtained. Since the outer shape of the obtained metal pipe is perfectly round, an after-treatment thereof can easily be performed. Since the cathode jig is stopped without rotating in the electroforming liquid in the method described above, the resin wire material arranged outside the stainless steel wire material of the center, or the metal wire material having the surface on which the resin is coated also stands still in the electroforming liquid, and the misalignment of the position of the wire material, that is, the misalignment of the position of the hole is eliminated.  
      In the embodiment mentioned above, a plastic molding in which a plurality of holes formed at exact positions and having an exact size are punched, a silicon plate manufactured by a photo-etching method of photoresist processing, and an insulating plate in which a plurality of holes are punched by NC processing due to a special drill can be used as the insulating plate of the cathode jig. Among these, the method using the plastic molding has a high aptitude, and particularly a quality of a material having a low linear expansion coefficient, such as an epoxy resin, PPS resin and phenol resin in which a great deal of fillers are mixed is preferably used.  
      Though the stainless wire material is used for the wire material  5  of the center in the plurality of wire materials set in the cathode jig in the present invention, in addition, a metal material having conductivity, such as phosphor bronze can also be used, and a minus current is passed only to this wire material of the center. The quality of the material of the wire material other than the center may be a conductive metal such as stainless steel and phosphor bronze. The quality of the material may be the resin wire material having no electrical conductivity, or the metal wire material having the surface on which the resin is coated. Some ovalization of the sections having no problem in an electroforming part appear at the time of electroforming by using the conductive wire material for the wire material other than the center. However, when the resin wire material, or the metal wire material having the surface on which the resin is coated are used, since the resin wire material, or the metal wire material having the surface on which the resin is coated does not affect an electrolytic deposition operation at all at the time of electroforming, the accuracy of the position becomes better, and the section shape of a generated electroformed product becomes almost perfectly round. That is, in the present invention, it is more preferable that the wire material  5  having no conductivity is used for wire materials other than the center.  
      Though nickel is used as the electroforming metal in the present invention, other metals such as cobalt can also be used. In detail, as the quality of the material of the electroforming metal, for example, nickel or an alloy thereof, iron or an alloy thereof, copper or an alloy thereof, cobalt or an alloy thereof, a tungsten alloy, a particle dispersed metal or the like can be used. As the electroforming liquid, an aqueous solution composed mainly of an aqueous solution of nickel sulfamate, nickel chloride, nickel sulfate, ferrous sulfamate, ferrous fluoborate, copper pyrophosphate, copper sulfate, copper fluoborate, copper silicofluoride, copper titanium fluoride, copper alkanol-sulfonate, cobalt sulfate and sodium tungstate or the like, or a solution obtained by dispersing a fine powder of silicon carbide, tungsten carbide, boron carbide, zirconium oxide, silicon nitride, alumina and diamond or the like in these solutions is used. Among these, particularly, the solution composed mainly of nickel sulfamate is suitable in respect to the ease of the electroforming, the diversity of physical properties such as hardness, chemical stability, and the ease of welding, and the safety of the electroforming liquid. It is preferable that the electroforming liquid is filtered at high speed by a filter having a filtration accuracy of about 0.1 to about 5 μmm and the temperature is controlled within the range of appropriate temperature of about ±3° C. by heating.  
      It is preferable that the metal pipe is taken out from the electroforming tank, is sufficiently washed and is dried after the direct current is set to a current density of about 3 to 8 A/dm 2  and the electroforming metal grows to a predetermined thickness at the time of electroforming.  
     EFFECTS OF THE INVENTION  
      As described above, according to the present invention, the anode is revolved or the anode is arranged substantially perfectly round around the negative pole without making the cathode jig rotate. Thereby the misalignment of the holes formed on the metal pipe is eliminated, and the outer shape of the metal pipe can be formed substantially perfectly round.  
      The present invention can be used at the time of manufacturing the multi-core metal pipe used for the nozzle of the injection pump for the engine and the nozzle of the ink-jet printer or the like, in addition to manufacturing of the multi-core metal pipe used for the multi-core ferrule such as the connector for the optical fiber and the device.