Method and device for manufacturing metal ferrules used for optical fibers

<img img-format="tif" img-content="drawing" file="IL159574AD00021.tif" id="idf0001" />

If □"□six D'zi'on win'E/b pirn τιιυηυ ίιϊ"1? ιρηηι no'w

METHOD AND DEVICE FOR MANUFACTURING METAL FERRULESUSED FOR OPTICAL FIBERS 01PCT012 /?' 1

Method and Device for Manufacturing Metal FerrulesUsed for Optical Fibers

Detailed Description of the Invention

Field of the Invention 5 The present invention relates to manufacturing metal ferrules for optical fibers usedprincipally for optica] telecommunications arid the like, and especially relates to amanufacturing method and device for metal ferrules used as connector elements foroptical fibers (hereinafter referred to as “metal ferrules”) in which a metal ferrule isobtained from a tube-shaped electroformed layer that is grown by electroforming. 10 Description of the Related Art A variety of cylindrical ferrules (ferrule: A cylindrical part for coaxially opposing theterminals of optical fiber strings to each other. It is used to connect the opposite ends ofoptical fiber strings.) are conventionally used as connector elements for connectingoptical fibers developed principally for optical telecommunications. 15 Such a ferrule is conventionally manufactured in the following way: a mixture of zirconia powder and resin is formed by injection molding or extrusion molding into acylindrical shape and is later baked around 500 °C for decomposing and removing theresin and in addition the same is baked around 1200 °C. Thereafter, diamond abrasion isapplied to a hole of the aforementioned ferrule (baked product) so as to adjust the hole 20 diameter within the allowable margin of error, and mechanical processing such asgrinding is applied to the center of the hole so as to make the periphery of theaforementioned ferrule a true circle.

However, the conventional methods of manufacturing ferrules have difficulties, asfollows: 01PCT012 s. u 2 (1) An expensive molding device or metallic pattern is needed for injection molding orextrusion molding and, in addition, such metallic patterns are easily abraded by thezirconia powder, and therefore special processing such as applying cemented carbide tothe molding surface of the metallic pattern is necessary, and the abrasion must 5 constantly be monitored so that repairing or changing of the metallic pattern can beperformed when necessary. (2) Time and special skills are needed to perform the diamond abrasion of the piercinghole, and therefore it is difficult to increase productivity. (3) The baking temperature is high, which requires a great deal of energy at high cost. 10 (4) According to the type of physical-contact connection (hereinafter referred in short to as a “PC connection”), the ferrule of which material is ceramics, the PC connectionmust be processed on its end face to form a convex spherical surface, an inclinedconvex spherical surface, a flat surface, an inclined flat surface, or the like, but thematerial (ceramics) that is used makes such processing difficult. 15 To solve these problems, for example, the electroforming method shown in PCT/JP99/06570 (Title of the Invention “Optical fiber connector and ferrule usedtherein and manufacturing method for the ferrule”) is used to form a ferrule that is madeof a metallic material. Such process as included herein is one in which the metal isaccumulated around a core string member (the external diameter thereof is the same as 20 the internal diameter of the ferrule) that is dipped in an electroforming cistern to form atube-shaped electroformed layer, one in which the core string member is removed fromthe tube-shaped electroformed layer, and one in which the formed electroformed layeris cut into a prescribed length so as to obtain the necessary ferrule.

However, in this electroforming method, the length of the tube-shaped electroformed 25 layer (namely, a part of the core string member that is dipped in the electroforming liquid) is restricted by the depth of the electroforming cistern, and therefore the volumeobtained by one electroforming process is small. Also, this is batch-type electroforming 01PCT012 k 3 processing wherein a number of core string members are repetitively dipped and takenout, and therefore the method is not suitable for mass-production. Also, in order toimprove the concentricity, circularity, and cylindricity of the electroformed layer, it isnecessary to maintain a fixed distance between the core string member as a cathode and 5 an anode under electroforming, and therefore a contrivance for an electroforming cistern, and placement of electrodes or structure. Furthermore, it is difficult to make thecircularity, cylindricity or surface roughness of the tube-shaped electroformed layerwithin the required accuracy limits. '

The present invention is based on the aforementioned situation and the purpose of the 10 present invention is to provide a manufacturing method and device by which metalferrules are continuously manufactured by an electroforming method in such a way asto increase the mass-production of such metal ferrules and to decrease the cost ofmanufacturing them, as well as to ensure the uniformity of the concentricity, circularity,cylindricity, and electroforming accumulation of the intemal/extemal diameters of the 15 electroformed layer. A second purpose of the present invention is to provide metal ferrules to be used inpractice in the forming process of the tube-shaped electroformed layer. A third purpose of the present invention is to provide metal ferrules in such a way as toprevent the arising of small hollows in the tube-shaped electroformed layer, especially 20 in the internal wall, and to minimize the depletion of optical signals by removing bubbles in the electroforming liquid in the early stage of electroforming and improvingthe wetness of the surface of the core string member. A fourth purpose of the present invention is to provide a manufacturing device formetal ferrules that enables the confirmation of the difference of the electroforming 25 liquid pressure in the vertical direction, convenience for change and maintenance ofanodes, and the growth-of the electroformed layer, in the electroforming process, byadopting a plurality of electroforming cisterns used in steps as a multitiered structure. 01PCT012 .ι&gt; 4

Disclosure of the Invention

In order to achieve the aforementioned purposes, the present invention’s method of manufacturing metal ferrules is characterized such that, in the electroforming method where a metal ferrule is grown in the electroforming process as a cathode opposed to 5 the anode furnished in the electroforming cistern, an electroformed layer having acylindrical internal hole is grown in the electroforming cistern, on the cathode sidethereof, with the growth of said electroformed layer being guided by aninternal-diameter-formation member whose external diameter is the same as the internaldiameter of the cylindrical metal ferrule to be manufactured, and such that a 10 tube-shaped electroformed layer that, in the process of being pulled up from the aforementioned electroforming cistern, is grown so as to have the intended externaldiameter is cut to the prescribed dimensions when outside the aforementionedelectroforming cistern.

Also, the present invention’s method of manufacturing said metal ferrules is 15 characterized such that, on the cathode side that is opposed to the anode furnished in theelectroforming cistern, an internal-diameter-formation member whose external diameteris the same as the internal diameter of the cylindrical metal ferrule to be manufacturedis supplied as a cathode core member upwardly through the bottom portion of theaforementioned electroforming cistern, around which is grown, in the electroforming 20 cistern and on the cathode side thereof, a tube-shaped electroformed layer having a cylindrical internal hole, and such that, in the process of lifting from the aforementionedelectroforming cistern such tube-shaped electroformed layer together with theaforementioned internal-diameter-formation member, the aforementioned tube-shapedelectroformed layer, which is grown so as to have the intended external diameter, is cut, 25 when outside the aforementioned electroforming cistern, to the intended dimensions.

Also, the present invention’s method of manufacturing said metal ferrules ischaracterized such that, on the cathode side that is opposed to the anode furnished in theelectroforming cistern, a cylindrical member whose internal diameter is the same as the 01PCT012 interna] diameter of the cylindrical metal ferrule to be manufactured is supplied as a cathode core member upwardly through the bottom portion of the aforementioned electroforming cistern, around which a tube-shaped electroformed layer having a cylindrical internal hole is grown in the electroforming cistern, on the cathode side 5 thereof, and such that, in the process of lifting such tube-shaped electroformed layertogether with the aforementioned cylindrical member from the aforementionedelectroforming cistern, the aforementioned tube-shaped electroformed layer, which isgrown so as to have the intended external diameter, is cut to the intended dimensionswhen the aforementioned cylindrical member is outside the aforementioned 10 electroforming cistern.

Furthermore, the present invention’s method of manufacturing said metal ferrules ischaracterized such that, on the cathode side that is opposed to the anode furnished in theelectroforming cistern, an internal-diameter-formation member whose external diameteris the same as the internal diameter of the cylindrical metal ferrule to be manufactured 15 is supplied upwardly through the bottom portion of the aforementioned electroformingcistern, around which a tube-shaped electroformed layer having a cylindrical internalhole is grown in the electroforming cistern, on the cathode side thereof, and such that aspacer with an intended pitch is previously furnished in the aforementionedintemal-diameter-formation member, which is pulled up with the aforementioned 20 grown tube-shaped electroformed layer, and such that said spacer is such that at itsupper and lower ends there are formed the necessary faces of the upper and lowerterminals of the metal ferrule to be manufactured.

In these manufacturing methods, a uniform thickness from the outside of the innerspace to the circumference of the electroformed layer at any position along the length of 25 that layer is secured by rotating at an appropriate velocity, during the process of theaforementioned lifting, the aforementioned tube-shaped electroformed layer that isgrown by electroforming. 4 01PCT012 6

In the same way, in these manufacturing methods, by measuring the external diameterof the tube-shaped electroformed layer that is lifted from the aforementionedelectroforming cistern, the lifting velocity of the aforementioned tube-shapedelectroformed layer can be controlled and the intended dimension of the external 5 diameter of the region lifted out of the aforementioned electroforming cistern can bemaintained.

Also, the first embodiment of the present invention is characterized such that, as adummy of the aforementioned tube-shaped electroformed layer, a cathode core memberwhose external diameter and axis are the same as those of the aforementioned 10 intemal-diameter-formation member is vertically supported in the aforementionedelectroforming cistern so as to contact the upper end of the aforementionedinternal-diameter-formation member at the beginning of the electroforming process andso that a tube-shaped electroformed layer is grown on the surface of saidinternal-diameter-formation member. 15 In this case, it is desirable that a power supply (a direct-current power supply, or analternating-current power supply that is adjusted to load a certain biased voltagebetween the cathode and the anode) is connected with the aforementionedinternal-diameter-formation member and/or cathode core member so as to applycathode voltage to the aforementioned grown electroformed layer. 20 Also, in an embodiment of the present invention, the aforementioned cathode core member, which can be in a bar-shape, is desirably in a cylindrical shape, and it is alsonecessary to apply appropriate air pressure inside so as to prevent the electroformingliquid in the aforementioned electroforming cistern from intruding into theaforementioned electroformed layer during the growing process. 25 Furthermore, for an embodiment of the present invention, it is better that a member ofsmall diameter is connected with the top portion of the aforementionedintemal-diameter-formation member, that said small-diameter member is piercedthrough a cylindrical cathode core member so as to extend upwardly, and that upward 01PCT012 (.· « pressure is applied thereto so as to maintain the verticality of the aforementionedintemal-diameter-formation member so as to prevent shaking (and thereby to increasethe circularity, concentricity and cylindricity) of the aforementioned internal-diameter-formation member. 5 Also, it is necessary to control, in the bottom portion of the aforementionedeiectroforming cistern, the upward movement of the aforementionedintemal-diameter-formation member at a specified velocity in the process of lifting thegrown tube-shaped electroformed layer. In order to compensate for the unavoidabledepletion that is generated by electronic or mechanical waste in the eiectroforming 10 process, the external-diameter of the internal-diameter-formation member should bewithin allowable error limits. Also, cutting is done of the aforementioned tube-shapedelectroformed layer only under the condition that the aforementioned internal-diameter-formation member is not cut (in the case where aninternal-diameter-formation member whose external diameter is the same as the internal 15 diameter of the cylindrical metal ferrule to be manufactured is used as a cathode coremember and only the metal ferrule is removed after cutting), or cutting is done of theaforementioned tube-shaped electroformed layer together with the aforementionedinternal-diameter-formation member (in the case where the cylindrical member whoseinternal diameter is the same as the internal diameter of the cylindrical metal ferrule to 20 . be manufactured is used as a cathode core member and is left inside the metal ferrule).

In particular, the process of removing bubbles arising in the early stage of the beginningof the aforementioned continuous eiectroforming is included, whereby the arising ofhollows in the aforementioned continuously electroformed layer is effectivelyprevented. 25 The metal ferrules that are manufactured by such manufacturing methods and that areconstituted of a cylindrical metal layer having a hole whose internal diameter enablesthe aforementioned optical fibers to be pierced, have good workability and excellentproductivity. 01PCT012

Furthermore, to attain the above-mentioned purposes, the present invention’s device formanufacturing said metal ferrules is furnished with (1) a means of lifting a tube-shapedelectroformed layer that is grown in the aforementioned electroforming cistern, (2) ameans of measuring the external diameter ofthe aforementioned electroformed layeroutside the aforementioned electroforming cistern in the process of the lifting theelectroformed layer, and (3) a means of controlling the lifting velocity of theaforementioned lifter using the result of such measurement as a predicted measurementvalue in said manufacturing device, which, in the electroforming cistern, grows atube-shaped electroformed layer having an internal hole whose diameter is the same asthe internal diameter of the cylindrical metal ferrule being manufactured on the cathodeside of the aforementioned electroforming cistern, opposite to the anode.

In this case, it also is desirable for an embodiment of the present invention to furnish aninternal-diameter-formation member that has the same external diameter as that of theinternal diameter of the aforementioned metal ferrule and that is able to guide thegrowth thereof so as to form the aforementioned tube-shaped electroformed layer, andto furnish a means of supplying the aforementioned intemal-diameter-formationmember upwardly through the bottom portion of the aforementioned electroformingcistern and to grow around the circumference of said internal-diameter-formationmember a tube-shaped electroformed layer having a cylindrical internal hole in theelectroforming cistern, on the cathode side thereof. Also, instead of the internal-formation member, a cylindrical member whose internal diameter is the sameas that of the internal diameter of the aforementioned metal ferrule can be adopted as acathode core member to be used as it is for an internal-constituent member of the growntube-shaped electroformed layer.

Further, it is recommended to furnish, in the process of lifting the tube-shapedelectroformed layer from the aforementioned electroforming cistern, a means of cuttingthe tube-shaped electroformed layer that is grown so as to have a specified diameter. 01PCT012

Also, it is effective for an embodiment of the present invention that (1) the aforementioned internal-diameter-formation member that is lifted with the aforementioned grown tube-shaped electroformed layer be furnished with a spacerhaving a specified pitch, (2) appropriate surfaces of the upper and lower terminals ofthe metal ferrule to be manufactured are formed on the upper and lower ends of such aspacer, and (3) in the lifting of the aforementioned internal-diameter-formation member,there be a means of removing the tube-shaped electroformed layer formed between theaforementioned spacers from the aforementioned internal-diameter-formation member.

Furthermore, it is important for the present invention that an anode opposed to theaforementioned electroformed layer is placed so as to maintain a certain distance fromthe aforementioned electroformed layer so as to improve the circularity, concentricity,and cylindricity of the aforementioned electroformed layer, because the uniform-growing of the layer by electroformation is disordered if the distance betweenthe anode and layer varies beyond a certain limit, and therefore it is effective to use aninsoluble electrode such as platinum, gold, or titanium for the anode.

Also, it is important for the present invention to furnish a means of rotating, at aspecified velocity in the process of the aforementioned lifting, the aforementionedtube-shaped electroformed layer that is being grown by electroforming, and to secureequal thickness from the outer edge of the inner space to the circumference direction ofthe electroformed layer at each point along the entire length thereof, so as to improvethe circularity, concentricity, and cylindricity of the aforementioned electroformedlayer.

Furthermore, for an embodiment of the present invention, the aforementioned purposesare attained by adopting an electroforming cistern with a multitiered structure.

Brief Description of the Drawings 01PCT0J2 10 . Fig. 1 is a schematic vertical section view of a device for electroforming manufacturingof metal ferrules used for optical fibers, illustrating an embodiment of the presentinvention.

Fig. 2 is a plan view of the electroforming cistern of the same device for manufacturing5 metal ferrules.

Fig. 3 is a perspective view illustrating the principal parts of a rotator of the samedevice for manufacturing metal ferrules. '

Fig. 4 is a perspective view illustrating the principal parts of a cutter of the same devicefor manufacturing metal ferrules. 10 Fig. 5 consists of five separate illustrations that of the five steps of the electroformingprocess of the first embodiment of the present invention.

Fig. 6 is a schematic vertical-section side view of the principal parts of anelectroforming cistern, illustrating a second embodiment of the present invention.

Fig. 7 is a perspective view illustrating the principal parts of a cutter, used in a second15 embodiment of the present invention.

Fig. 8 is a schematic vertical-section side view of the principal parts of anelectroforming cistern, illustrating a third embodiment of the present invention.

Fig. 9 is a schematic vertical-section side view of the principal parts of anelectroforming cistern, illustrating a fourth embodiment of the present invention. 20 Fig. 10 is a schematic vertical-section side view of the principal parts of the multitieredstructure of the electroforming cistern of the present invention.

Fig. 11 is a transverse cross-sectional view of the principal parts of the multitieredstructure of the same electroforming cistern of the present invention. 01PCT012 11

Best Mode for Carrying Out the Invention

The embodiment of the present invention is described in reference to the accompanying figures, which are described immediately below.

The First Embodiment 5 The first embodiment of the present invention is described as follows, with reference tothe aforementioned figures. As shown by Figs. 1 to 4, the present invention’s devicefor manufacturing metal ferrules used for optical fibers grows, in the electroformingcistern 1, a tube-shaped electroformed layer (ferrule material) FE that has an internalhole whose diameter is the same as the internal diameter of the cylindrical metal ferrule 10 (it is a connector element) to be manufactured on the cathode side of the electroformingcistern 1, with said cathode side being opposite the anode 2 (which is desirablycomposed of an insoluble material such as platinum, gold, or titanium). Saidmanufacturing device is furnished, in particular, with: (1) a lifter 3 for lifting a tube-shaped electroformed layer FE that is grown in the 15 electroforming cistern 1, (2) a measurer 4 for measuring the external diameter of the electroformed layer FEoutside the electroforming cistern 1 in the process of lifting the electroformed layer, and (3) a controller 5 for controlling the lifting velocity of the lifter 3, using the result ofsuch measurement as a predicted measurement value. 20 Further, the anode 2, which is opposite the electroformed layer FE, is placed so as tomaintain a fixed distance from the aforementioned layer on the cathode side in theelectroforming cistern 1) and is constituted so as to improve the circularity,concentricity, and cylindricity of the aforementioned electroformed layer FE, forexample, by being placed in a cylindrical or arc shape around the aforementioned 25 electroforming cistern as the center thereof (further, a group of nickel balls can be usedas material for the anode). 01PCT012 12

For a more-detailed description, an intemal-diameter-formation member 6 whoseexternal diameter is the same as the internal diameter of the metal ferrule F is furnishedin the electroforming cistern 1 and with growth-guidance the tube-shaped electroformedlayer FE is formed (further, the internal-diameter-formation member 6 functions hereinas a cathode, and a material of high rigidity, such as cemented carbide withcorrosion-resistant plating, or stainless steel is used as the material thereof). For thisreason, there is furnished at the bottom portion of the electroforming cistern 1 a hole lathrough which the internal-diameter-formation member 6 is vertically protruded intothe electroforming cistern 1 from the lower side of the electroforming cistern 1. Further,in this embodiment, a support 7 is furnished to vertically support the internal-diameter-formation member 6, and for this support there is adopted a knownclamping system that clamps the internal-diameter-formation member from thesurroundings thereof and that is rotatable to the axis of the intemal-diameter-formationmember. Here in particular an elevator 8 (for example, a known elevating device isadopted) that controls the elevation of the support 7 is prepared, and theintemal-diameter-formation member 6 is elevated at a specified micro-velocity throughthe elevator 8 in response to a control signal S1 from the control system 9 (acomputerized control system, including the aforementioned controller 5) ofthe presentinvention. Also, the support 7 switches between clamping and releasing in response to acontrol signal S7 from the control system 9.

Electroforming liquid is supplied to the electroforming cistern 1 through a pump 10from a storing cistern 11, and, in order to keep a constant level of the electroformingliquid in the electroforming cistern 1, the electroforming liquid can overflow via a brimlb that is furnished on the upper edge of the electroforming cistern 1. Said overflowedelectroforming liquid is received by a receiving cistern 12 that is furnished under theelectroforming cistern 1. Said receiving cistern 12 is so constituted as to receive theelectroforming liquid that is flowing down from the hole la (thereby the surfacewetness of the cathode core member (dummy) described later is improved in the earlystage of electroforming). 01PCT012 13

Also, the electroforming liquid in the receiving cistern 12 is fed back to the storingcistern 11 by a pump 13 through a filter 14. Further, in a leading hole 12a that is formedin a tube that protrudes upwards from the bottom of the cistern 12 to above the level ofthe liquid and that is used when the internal-diameter-formation member 6 is piercedand a liquid-sealing member 15 is furnished to at least of the top of the tube (theinternal-diameter-formation member 6 is free to slide against the aforementionedliquid-sealing member 15 ). Further, the control of the driving of the pumps 10 and 13is performed by a control signal S2 from the aforementioned control system 9.

Furthermore, in this embodiment, in order to assist the growing of electroformed layerat time of the beginning of electroforming, a cathode core member 16 is adapted tomake contact with the upper end of the internal-diameter-formation member 6, thecathode core member 16 having an external diameter and axis that are the same as thoseof the intemal-diameter-formation member, and said cathode member 16 can beinserted, as a dummy of the tube-shaped electroformed layer FE, into theelectroforming cistern 1 from the upper direction and then lifted by the aforementionedlifter 3. In this embodiment, the lifter 3 is composed of (1) two supports 17 and 17’ (aknown clamping system that clamps the cathode core member 16 from the surroundingsthereof is adopted) that are the upper and lower tiers upwardly placed in theelectroforming cistern 1; and (2) an elevator 18 (for example, a known elevating-systemdevice is adopted). Further, the support 17 is moved up and down by the elevator 18while the support 17’ is maintained at a static level so as to be held in a fixed positionby a frame (not shown). Then, a tube-shaped electroformed layer FE is grown in theelectroforming liquid. That growing stops when the electroformed layer FE is at aposition above the surface of the electroforming liquid while the dummy is verticallysupported through the support 17 and the elevator 18 is elevated.

Further, the cathode core member 16 (or the electroformed layer FE) is moved up ordown at a specified velocity through the support 17 by control signals S3 and S3’ fromthe control system 9 of the present invention. Also, each of the supports 17 and 17’ 01PCT012 14 clamps or releases independently by means of the control signals S4 and S4’ from thecontrol system 9.

There also are furnished rotators 19(19’) for rotating, at specified velocities RI and R2,the tube-shaped electroformed layer FE (including a dummy as an object to be lifted)that is being grown by the electroforming process. Accordingly, the internal-diameter-formation member 6 can maintain a uniform thickness of theelectroformed layer FE from the outside of its inner space to its circumference along itsentire length in the process of the lifting thereof by control signals S5 and S5’ so as toimprove the circularity and concentricity of the electroformed layer FE. The rotators 19(19’) herein are desirably constituted, for example, as shown in Fig. 3.

That is to say, in this embodiment, ring-shaped rotators 191 (191’) that rotate aroundthe vertical axial line L, which is common with the tube-shaped electroformed layer FE(or a dummy) and the internal-diameter-formation member 6, are supported by asupport frame (not shown) through bearings 192 (192’) on which a right-and-left set oftwo clamps 193 (193’) are furnished. Further, gear teeth are formed on the circumferential edge of each of the rotators, and they connect with an electric motor M(for example, a stepping motor) through an appropriate gear transmission system (notshown), and the starting, stopping, and velocity thereof are controlled by the controlsignals S5 and S5’ from the control system 9 as described above. These clamps 193(193’) axially support levers 193b (193b’) that axially support rollers 193a (193a’) thatare drums having a narrow-in-the-middle shape, under the condition of free shaking onaxis-mounted stands 193c (193c’) that are furnished on the aforementioned rotators 191(191’). In addition, pulling coil springs 193d (193d’) are furnished between the levers193b (193b’)

In this constitution, the electroformed layer FE (dummy) and the intemal-diameter-formation member 6 can be sandwiched and held between the rollers193a (193a’). In addition, the rotation of the rotators 191 (19Γ) can be transmitted tothe electroformed layer FE (dummy) and the intemal-diameter-formation member 6. 01PCT012 15

Further, in this embodiment, the structure of the rotators 191 (191 ’) of the electroformed layer FE and that of the internal-diameter-formation member 6 is thesame, although different structures are allowed and appropriate known means can besubstituted.

Also, in this embodiment, a cutting edge 20 is furnished for cutting the electroformedlayer FE, in the process of lifting thereof, into a specified length as a ferrule to be used.Such cutter is constituted, for example, so as Jo cut with cutters 201 proceeding fromthe right and left sides of the electroformed layer FE, as shown in Fig. 4. Each of thecutters 201 is driven back and forth by an actuator 202 in response to a control signalS6 from the control system 9.

Further, after the elevator 18 is elevated in accordance with the cutting length (length ofthe ferrule) of the electroformed layer FE, the support 17’ is first clamped and thencutting occurs. Thereafter, the support 17 in the lifter 3 changes the holding regionthereof on the electroformed layer FE (lowering the clamping region). Therefore, theclamping of the support 17 is stopped by a control signal S4’ from the control system 9,and then the elevator 18 drops in response to a control signal S3. Then, after the support17 clamps, the support 17’ releases the clamp in response to the control signal S4.

Also, an optical sensor utilizing laser beams (for example, a measuring device utilizinga light-emitting diode or the like) is desirably used for the aforementioned measurer .4for measuring the external diameter of the electroformed layer FE outside theelectroforming cistern 1 in the process of lifting the electroformed layer. The measurer4 herein is not limited to the above-mentioned optical sensor (other available knownmeasuring devices can be used).

Further, in this embodiment, the number 21 denotes a power supply (a rechargeablebuttery, or power obtained through a direct-alternating current converter from analternating-power supply obtainable on the market, or furthermore, such power supplyas an adjusted alternating-current power supply as mentioned below) of voltage(direct-current voltage, or alternating-current voltage adjusted to load a certain biased 01PCT0I2 16 voltage between the cathode and the anode) applied between the anode 2 and theelectroformed layer FE, and the number 22 denotes a voltage regulator that is controlledby a control signal S6 from the control system 9.

The process of manufacturing said metal ferrules F by means of the above-mentionedmanufacturing device of the present invention is as follows. First, as shown in Fig. 5,the cathode core member 16 (dummy) that is clamped by the support 17 (see Fig. 1) isinserted into the electroforming cistern 1 by the action of the elevator 18 (see Fig. 1) soas to make contact with the internal-diameter-formation member 6, which is placedover the bottom portion of the electroforming cistern 1. Further, in this embodiment, atthe end of the internal-diameter-formation member 6 is formed a small passageway 6awith which the end of the dummy is to be engaged under the condition of freeengagement/disengagement and of free rotation (otherwise, because the internaldiameter of the dummy corresponds to the external diameter of the internal-diameter-formation member 6, the engagement thereof under the condition ofpossible sliding to the end side of the internal-diameter-formation member 6 ispossible).

Under this condition, when electroforming begins, a metal layer begins to be formed byelectroforming in the region of the cathode core member 16 that is dipped in theelectroforming liquid and on the external circumferential surface of theinternal-diameter-formation member 6 that is protruding into the electroforming liquid(see (2) of Fig. 5). At the stage where the electroformed layer FE has grown to thenecessary thickness (thick enough not to give rise to damages such as cracks and toexfoliate smoothly against the intemal-diameter-formation member 6, by being able torotate with the dummy side if the dummy is rotated by the rotator 19 and a twistingforce is applied to the metal layer between itself and the intemal-diameter-formationmember 6 which is not rotated, that is to say, around 0.5 pm thick, for example), therotator 19 is caused to rotate and also the dummy is lifted by the lifter 3. At this time,the rotator 19’ also is rotated, and the driving velocity of the electric motors M of eachof the rotators 19 (19’) is separately controlled by control signals from the control 01PCT012 17 system 9 so as to make the rotation-speed difference between the two rotators either zero or a specified amount.

In this lifting process, the lower end of the dummy leaves the upper end of theinternal-diameter-formation member 6 while the tube-shaped electroformed layer FEthat is formed by the electroforming work continues to grow, maintaining the internaldiameter of the intemal-diameter-formation member 6 (see (3) of Fig. 5). When thedummy is elevated and the tube-shaped electroformed layer FE reaches the level of themeasurer 4 (see (4) and (5) of Fig. 5), the external diameter of the tube-shapedelectroformed layer FE is measured from that stage. The lifting velocity of the lifter 3decides the external diameter of the tube-shaped electroformed layer FE that is beinglifted from the electroforming liquid. Then, as a result of the measurement of theexternal diameter of the tube-shaped electroformed layer FE by the measurer 4, whenthe specified diameter (ferrule external diameter) is reached, the lifting velocity of thelifter 3 is controlled by feed-back control so as to maintain the; value thereof. In thisway, the measured value by the measurer 4 is used as a predicted value (equivalent tothe set value) to keep a constanf external diameter of the tube-shaped electroformedlayer FE.

In the condition where the measured external diameter of the tube-shaped electroformedlayer FE maintains the prescribed value, when the length of the tube-shapedelectroformed layer FE by the lifter 3 reaches the prescribed length of the ferrule, thesupport 17’ clamps the immediate upper region of the cut portion of the tube-shapedelectroformed layer FE in response to a control signal from the control system 9. Underthis condition, in response to control signals from the control system 9, the cutting edge20 is caused to cut the tube-shaped electroformed layer FE. Later, by in response tocontrol signals from the control system 9, the aforementioned support 17 changes theholding region (that is to say, release of the clamp by the support 17, lowering of theelevator 18, and reclamping at a new position by the support). Further, the holdingregion of the support 17 is changed after cutting in this embodiment, but in the other 01PCT012 18 - embodiment, cutting can be done after the change of the holding region of the support17 after the clamp of the support 17’.

Also, the part that is first cut from the tube-shaped electroformed layer FE (includingthe dummy) is removed in an appropriate manner after releasing the clamp of the 5 support 17’, and the pieces that are cut later from the tube-shaped electroformed layerFE are taken as ferrules F in an appropriate way and are placed in storage as specified.Then, again, in the course of the growth of the tube-shaped electroformed layer FE, theelevator 18 is elevated while the clamped condition is maintained by the support 17 (asdescribed above, the support 17’ is in a clamp-released condition). 10 Further, in this embodiment, the dummy is hollow, and from the upper end of which apressurized gas (a gas such as air) is supplied to prevent the electroforming liquid fromsinking into the tube-shaped electroformed layer in the electroforming cistern 1. In thiscase, a known means of supplying the pressurized gas (not shown) can be used. Thepurpose of this is to prevent the electroforming liquid from disturbing the condition 15 where the internal diameter of the tube-shaped electroformed layer FE is retained at aprecise value by the internal-diameter-formation member 6.

Furthermore, it is possible to connect a member of small diameter (not shown) on thetop portion of the internal-diameter-formation member, and for the same member topierce through the cylindrical cathode core member (dummy) and be extended 20 upwardly with an upward pressure so as to maintain the verticality of the internal-diameter-formation member 6 so as to eliminate the shaking thereof (thereby toincrease the circularity, concentricity, and cylindricity of the growing electroformedlayer).

Also, considering that the tip portion (the part exposed to the inside of the 25 electroforming cistern) of the intemal-diameter-formation member gradually becomesthinner in the process o*f electroforming, it is effective to control theintemal-diameter-formation member 6 so that it is elevated at a micro-velocity by theelevator 8 so as to proceed to the allowable extent into the tube-shaped electroformed 01PCT012 19 ' layer that is formed. Such control of the elevator 8 is effected via the control signal SIfrom the control system 9.

Further, the internal diameter of the tube-shaped electroformed layer FE to bemanufactured in this embodiment is, for example, 0.05 mm-0.13 mm, and the external 5 diameter thereof is, for example, 1 mm-1.2 mm. Also, for the electroformed layer, suchmaterials as nickel, iron, copper, cobalt, tungsten, or alloys thereof can be used.Therefore, as for the electroforming liquid, the metal constituents mentioned above arecontained in the condition of a solution or flotation liquid (suspension liquid). Forexample, there is used an aqueous solution such as nickel sulfamate, nickel chloride, 10 nickel sulfate, ferrous oxide sulfamine, ferrous oxideborofluoride, copper pyrophosphate, copper borofluoride, copper silicafluoride, copper titanfluoride, copperalkanolsulfonate, cobalt sulfate or sodium tungstate, or a flotation liquid (suspensionliquid) that is composed of water with the fine powder of silicon carbide, tungstencarbide, boron carbide, zirconium oxide, silicon nitride, alumina, or diamond. Further, a 15 solution containing sulfamate is extremely useful as an electroforming liquid because itenables easier electroforming, is chemically stable, and dissolve easily.

Further, in this embodiment, because the metal constituents of the electroforming liquidare to be materials composing metal ferrules used for optical fibers, it is desirable thatsuch materials be easy-to-cut materials, for example, nickel or nickel alloys such as 20 nickel/cobalt alloys, if the metal ferrules are for optical fibers used for PC connections.

Also, for the intemal-diameter-formation member 6 or the cathode core member 16 as adummy, such materials as a stainless alloy (such as SUS304 in the JIS Standard) wirerod are used. As such wire rods, the ones having a diameter of 125.0 ± 0.2 pm,manufactured by an extrusion method with a die or wire-drawing method by ductile 25 extension, can be obtained easily.

Also, plus or minus direct currents are applied to the anode 2 that is connected with thepower supply and the tube-shaped electroformed layer FE of the cathode side that iselectrically connected to the power supply 21 through the intemal-diameter-formation 01PCT012 20 member 6 or the cathode core member 16, in the case of which the current densitynormally used is 4-20 AHF. In this case, the pH of the electroforming liquid is kept onthe acid side (pH 3-6), preferably pH 4-5. In this case, for example, within 12 hoursafter the application of power, and usually within 3-8 hours, the tube-shapedelectroformed layer FE can be thickened to the intended diameter in the electroformingcistern 1, though the result is subject to the depth of the electroforming liquid.

Also, organic impurities are regularly removed from the electroforming liquid, by using,for example, active carbon. Also, prior to the electroforming, it is recommended to dipa different cathode such as a nickel-plated iron corrugated plate in the electroformingliquid and to apply a direct current between that plate and the anode 2 at a low-currentdensity of around 0.2 AUF so as to remove in advance any existing inorganic impurities,such as steel, from the electroforming liquid.

Further, it is possible to utilize the tube-shaped electroformed layer, after it has been cutto the prescribed length in accordance with the intended use thereof, as a metal ferrulewithout any other processing, but usually cutting is applied to the outside oftube-shaped electroformed layer with sub-micron accuracy (within ± 0.5 pm) so as tomake a true circle by NC mechanical processing or the like. In the present invention, ifthe difference between the internal and external diameters of the tube-shapedelectroformed layer is 2 mm or less, the eccentricity of the metal ferrule as a productcan easily be within 0.5 pm. In particular, by keeping a certain space between the anode2 and the tube-shaped electroformed layer, and in addition, by rotating the tube-shapedelectroformed layer by the rotator 19, the eccentricity can be kept low if theaccumulation thickness is large.

Second Embodiment

The second embodiment of the present invention is described as follows. Herein, thecathode core member Γ6 (dummy) shown in the first embodiment is not used. As acathode opposed to the anode furnished in the electroforming cistern 1, theintemal-diameter-formation member 6, whose external diameter is the same as the 01PCT012 21 . internal diameter of the cylindrical metal ferrule to be manufactured, is supplied upwardly through the bottom portion of the aforementioned electroforming cistern to bedirectly supported at its upper end by the support 17. In the electroforming liquid,around said internal-diameter-formation member 6, a tube-shaped electroformed layer 5 FE having a cylindrical internal hole is grown on the cathode side of the electroformingcistern 1 (see Fig. 6). Also, the support 7 and the elevator 8 are not used. Further, theother constituents and controls are the same as in the first embodiment and are not described herein.

In this case, for the cutting edge 20, it is recommended to form a cutting edge so as to 10 cut only the tube-shaped electroformed layer FE, without cutting the internal-diameter-formation member 6, as shown in Fig. 7, for example. Then, the cutpieces (ferrules) of the tube-shaped electroformed layer after cutting are upwardly takenout by an appropriate means when the holding region of the support 17 is changed.Thereby, the internal-diameter-formation member can be reused. 15 Third Embodiment

The third embodiment of the present invention is described as follows. Herein, insteadof the intemal-diameter-formation member 6 in the second embodiment, a cylindricalmember 6’ whose internal diameter is the same as the internal diameter of the necessarymetal ferrule (ferrule) is used (see Fig. 8). Also, the material thereof is desirably the 20 same as the metal accumulated around the member 6’ by the electroforming (for example, when a nickel alloy is accumulated, the member 6’ is of the same material). Inthis case, the cutting edge 20, which is used in the first embodiment (see Fig. 4), cutsthe member 6’ together with the electroformed layer in the surroundings thereof. Hereinthe member 6’, as a part of the ferrule, is left in the electroformed layer. Further, the 25 other constituents and controls are the same as in the first embodiment and are not zdescribed herein.

Fourth Embodiment 01PCT012 22

The fourth embodiment of the present invention is described as follows, with referenceto Fig. 9. Herein, in the intemal-diameter-formation member 6 that is lifted togetherwith the grown tube-shaped electroformed layer FE, a spacer S (composed of anonconductive material, such as ceramic) having a specified pitch is previouslyfurnished, and there is formed in the upper and lower ends a necessary face (such as ataper face, back-taper face) of the lower and upper terminals of the metal ferrule to bemanufactured. Also, as shown in the second embodiment, the tube-shapedelectroformed layer is accumulated and formed between the aforementioned spacerswhen the internal-diameter-formation member 6 is lifted.

Also, in the upper region of the eiectroforming cistern 1, there is furnished anappropriate means (not shown) of removing the formed tube-shaped electroformedlayer FE from the intemal-diameter-formation means. Herein, for example, the adoptedmethod is that the intemal-diameter-formation member 6 and the tube-shapedelectroformed layer FE of a specified length are previously left by such contrivance forspacer-removing by adopting a division-type spacer, especially of a verticaldivision-type, and later the tube-shaped electroformed layer FE is removed from theintemal-diameter-formation member 6. Further, the other constituents and controls arethe same as in the first embodiment and are not described herein.

Other Embodiments

Further, in the above-mentioned embodiments of the present invention, the constitutionof the electroforming cistern is merely in combination with the receiving cistern 12. But,as shown in Fig. 10, a vertically multitiered type cistern can also be used. In this case,the space between the hole la that extends through the internal-diameter-formationmember and the electroformed layer FE conveys the flow of the electroforming liquidfrom the upper cistern to the lower cistern. Also, it is recommended for the overflow toproceed from the upper tier to the lower tier as in the first embodiment (by saidoverflow the electroforming liquid is brought to the storing cistern 11 in the lowest tier(not shown)). Hereby, the problem of vertical variation of the water pressure is solved, 01PCT012 23 - and both the exchange of anodes and maintenance work are more easily accomplished.Further, by measuring the diameter of the growing electroformed layer FE between thecisterns, the growth condition of the electroformed layer can be observed in theeiectroforming process. 5 Further, in this embodiment, as shown in traverse section (a) of Fig. 11, the multitieredeiectroforming cistern is composed of semi-cylindrical bodies that are connected byscrews in the flange 101 formed therein (see (b) of Fig. 11) or are open sideways by thehinge 102 furnished on one side thereof. In this case, the anode 2 is desirablyconstituted to be in semi-cylindrical-shape contact with the internal wall of the 10 eiectroforming cistern 1 (see (c) of Fig. 11).

Also, in the early stage of the present invention’s method of eiectroforming, bubblesarising in the eiectroforming liquid should be removed because such removal preventsthe arising of hollows in the accumulated tube-shaped electroformed layer. In particular,for removing bubbles on the exposed surface of the cathode core member (the dummy 15 16, the intemal-diameter-formation member 6, or the cylindrical member 6) so as to improve the wetness, for example, the following process can be used while controllingthe liquid’s temperature. (1) Move the cathode core member in and out of the solution several times. (2) Release a comparatively large bubble from the lower side of the cathode core 20 member. (3) Oscillate the cathode core member in the solution. (4) Rotate the cathode core member at a high velocity.

Herein, because the dummy 16 as a cathode core member or theinternal-diameter-formation member (cylindrical member) 6 determines the internal 25 diameter of the metal ferrule, that is to say, the hole diameter of the hole through whichoptical fiber strand is inserted, high accuracy is needed to ensure the uniformity of the 01PCT012 24 - thickness, circularity (approximation degree between the intended diameter and the obtained diameter in the cathode core member), and linearity of the ferrule F.

Also, in the present invention, in order to keep the concentricity and circularity of theinternal and external diameters of the electroformed layer FE within the prescribed 5 limits, when the dummy 16 as the cathode core member or the internal-diameter-formation member (cylindrical member) 6 is rotated, it is possible toadjust the velocity of rotation or to change the current value to be applied in electrolysis,if necessary.

Further, if the diameter of the electroformed layer is not sufficient when the 10 electroformed layer is lifted, based on the value measured by the measurer, it isrecommended to decrease the lifting velocity so as to prolong the time that theelectroformed layer remains in the electroforming liquid. Also, as shown in Fig. 1, inany of the embodiments, in order to maintain a constant taper (related to accumulationvelocity) in the longitudinal direction of the electroformed layer in the electroforming 15 liquid, it is essential to place the electroformed layer and anode are parallel to eachother.

The metal ferrules that are produced according to the present invention that isconstituted in this way, can be very advantageously utilized as parts for connecting theterminals of optical fibers, either temporarily or permanently, for a variety of uses in 20 optical devices. Also, when necessary, the metal ferrules produced according to the present invention, which enables the external diameter thereof to be as small as possibleand smaller than a conventional ferrule, can enhance the package density of opticalfibers as a multi-core ferrule (ferrule) in a variety of connectors, including jack-typeconnectors, adapters, or receptacles. In the same way, the extremely small eccentricity 25 of said metal ferrules enables optical fibers to be connected more accurately, reducingthe loss of optical signals accompanied by the connection.

Also, the length of the metal ferrules (ferrules) is appropriately selected and set inaccordance with the connector structure or the like. Further, in the metal ferrules of the 01PCT012 25 present connection, according to the use thereof, such portions as one end face or bothend faces of the metal ferrules are desirably processed, for example, to be flat-shaped,or for the purpose of easier insertion of optical fibers therein, to be a back-taper facewith an appropriate angle.