JP3379131B2 - Mold for manufacturing ferrule for multi-core optical connector and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-fiber optical connector capable of connecting a plurality of optical fibers together, and more particularly to an improved die for manufacturing a ferrule for the multi-fiber optical connector, and a multi-fiber optical connector. The present invention relates to a method for manufacturing a ferrule for a connector.

[0002]

2. Description of the Related Art In a tape electric wire provided with a plurality of optical fibers, a multi-fiber optical connector is used as a connector for connecting the optical fibers together. A conventional example will be described with reference to the drawings.

FIG. 3 is a schematic view showing the appearance of a conventional die for manufacturing a ferrule for a multi-fiber optical connector. FIG. 4 is a schematic view showing the appearance of a conventional ferrule for a multi-fiber optical connector. FIG. 5 is a schematic diagram showing the structure of the multi-fiber optical connector.

That is, as an optical connector of this type, a ferrule 100 formed by using a plastic molding material such as epoxy resin and having a shape as shown in FIG. 4 is used, and an optical fiber is provided at the center side. 5, and a guide hole 105 into which a guide pin 104 for correctly positioning the multi-fiber optical connectors 102 and 103 is fitted is formed on both sides thereof. (In this multi-core optical connector, a ferrule with an optical fiber tape attached is called an optical connector.)

When manufacturing a ferrule of this type, for example, a pair of dies as shown in FIG. 3, a lower die 106, an upper die 107 and core pins 108, 109.
The slider 110 having a fixed position is used for molding by transfer molding, injection molding, or the like.

One of these molds, a mold 106, has a hole 101 for inserting an optical fiber and a guide pin 10.
V groove 106 for setting core pins 108 and 109 of two sizes, large and small, for forming the guide hole 105 for fitting 4
It has a V-groove portion 111 in which a plurality of a are formed and a main body 112.

The other mold 107 is provided with a resin passage 107a. When actually molding the ferrule, the slider 110 is set in the mold 106, the molds 106 and 107 are clamped by the transfer molding machine, and the resin is injected through the flow path 107a.

After the resin is hardened, the transfer molding machine is opened, the slider 110 is pulled out, and the ferrule is taken out. As the material of the mold, mold steel such as SKD11 or zirconia ceramic is generally used, and as the material of the molding pin, SUS440C or the like is used.

The multi-fiber optical connector manufactured as described above is required to be able to be quickly and easily attached / detached at the connection portion when it is used, but when combined as a connector, the optical fibers are precisely concentric with each other. Needs to be done.

For example, at present, an optical connector with an average splice loss of 0.35 dB is obtained with an SM fiber by using a ferrule with an average deviation of the fiber hole axis of 1.0 μm.

[0011]

In order to obtain an optical connector with low splice loss, it is necessary to use a ferrule with a small eccentricity. In order to obtain a ferrule that enables this, it is important that the V-groove processing accuracy of the mold is high and that the V-groove position of the mold is accurately transferred to the hole position of the ferrule. .

Among these, in the case of a multi-fiber optical connector, the V-groove machining accuracy of the die is required to be not only the depth angle of each V-groove alone, but also the pitch depth of the V-grooves to be superprecision machined. There is. To obtain a ferrule with an average eccentricity of 1 μm
The precision of the groove must be submicron.

However, such V-groove processing is difficult, and the reality is that many molds can be made and a suitable mold is selected from them. Further, there is a demand for a multi-fiber optical connector with a low connection loss from the current state of affairs, and it is more and more difficult to obtain a mold with high precision.

Next, it is necessary to accurately transfer the position of the V-shaped groove of the mold to the hole position of the ferrule, but in reality there is a variation of the order of 1 μm. I think that the reason for this poor transferability is complicatedly related to, for example, variations in the curing shrinkage ratio of the resin and warpage of the molded product. One of the reasons is that the space created by the V groove and the upper mold is This is because the core pin is not completely inscribed and there is a play allowance (see Fig. 2).

Since the core pin can move within the play allowance range,
The hole position of the ferrule is not transferred to the V groove position. As a countermeasure, it is possible to eliminate the play allowance, but since the depths of the plurality of V grooves of the multi-fiber optical connector cannot be perfectly aligned as described above, the play allowance of the core pin cannot be eliminated.

That is, even if the depth of the V groove is machined so that the core pin is just inscribed, if the machining accuracy in the depth direction is, for example, ± 1 μm, the core pin of 1 μm may play and the transferability is improved. become worse.

[0017]

In view of the above problems, the present inventor considers that the ferrule should be manufactured in a space which can be formed when the mold is clamped by a molding machine, at a mold temperature at the time of molding the ferrule. The inventors have found that the play allowance of the core pin can be eliminated when the diameter of the inscribed circle is made smaller within a specific range than the diameter of the core pin at the ferrule molding temperature, and the present invention has been completed.

Also, a method of molding a ferrule for a multi-fiber optical connector using the mold has been completed. That is, the present invention provides: a ferrule manufacturing die for molding a ferrule for a multi-fiber optical fiber connector, which has a hole for mounting a large number of optical fibers and a hole for mounting a guide pin for connecting ferrules to each other. The mold includes a lower mold having a plurality of V grooves for positioning the core pin for forming the optical fiber mounting hole and the guide pin mounting hole, an upper mold to be combined with the lower mold, and a core pin holding the core pin. The core pin is inserted into the cavity formed by the upper mold and the lower mold, and the core pin is along the V groove of the lower mold .
In a die for manufacturing a ferrule for a multi-fiber optical connector, which is composed of a slider that is positioned in accordance with the present invention , ferrule molding of a space formed when the V-grooves of the upper die and the lower die are clamped for all of the V-grooves. The diameter of the inscribed circle at the mold temperature at this time is made to be 0.5 μm to 4.5 μm smaller than the diameter at the ferrule molding temperature of the core pin, for manufacturing a ferrule for a multi-fiber optical connector Provide mold,
Also,

It is also characterized in that the longitudinal elastic modulus of the material used for the core pin is larger than the longitudinal elastic modulus of the material used for the lower die, and further, (1-ν ² ) / E from the material (1
Another feature is that −ν ² ) / E is smaller. Furthermore (however, E: longitudinal elastic modulus, ν: Poisson's ratio)

A lower mold having a plurality of V-grooves for positioning the core pin for forming the optical fiber mounting hole and the guide pin mounting hole, an upper mold to be combined with the lower mold, and a core pin for holding the core pin. The core pin inserted into the cavity formed by the upper mold and the lower mold is a V groove of the lower mold.
A mold composed of a slider positioned along the mold is attached to a molding machine, and the mold is clamped, resin is injected into the cavity of the mold, and holes for attaching a large number of optical fibers and ferrules are connected to each other. In a method of manufacturing a ferrule for a multi-fiber optical connector having a hole for attaching a guide pin to be coupled, a ferrule of a space formed when the upper and lower V grooves are clamped with respect to all the V grooves of the lower mold. The diameter of the inscribed circle at the mold temperature during molding is 0.5 μm to 4. compared with the diameter of the core pin at the ferrule molding temperature.
The mold is configured to be smaller by 5 μm, and in this state, the core pin is set in the V groove of the lower mold, and the upper mold is closed by the V groove of the lower mold, the upper mold, Provided is a method for manufacturing a ferrule for a multi-fiber optical connector, in which a mold is clamped while deforming the core pin, and a resin is injected and molded into a cavity portion of the mold that has been clamped to obtain a ferrule for the multi-fiber optical connector.

A detailed description will be given below with reference to the drawings. Here, the mold temperature during ferrule molding is
When using materials with different thermal expansion coefficients for the core pin and lower mold,
This is because the difference between the diameter of the inscribed circle and the diameter of the core pin changes depending on the temperature, and the actual transferability depends on the mold temperature during molding.

Further, it is desirable that the longitudinal elastic modulus of the core pin be larger than that of the lower mold. More preferably, the coefficient represented by (1-ν ² ) / E of the upper mold is smaller than that of the lower mold.

Regarding the upper die, not all of the die, but only the portion corresponding to the V groove portion and the core pin of the lower die (1-ν ² ).
A material having a large / E may be used. (However, E: longitudinal elastic modulus, ν: Poisson's ratio)

[0024]

According to the present invention, by positioning the core pin in accordance with the V groove and deforming the ferrule hole position,
When the core pin is accurately transferred, the eccentricity of the ferrule can be improved more than the V-groove processing accuracy. Furthermore, it demonstrates in detail.

As shown in FIG. 2, the term angle α and the inscribed circle diameter d
Set the core pin of diameter D (ξ = D−d) in the V groove of
When the mold is clamped, the sink amount Δ of the center of the core pin based on the lower mold is calculated. [Here, ξ is 0.5 ≦ δ ≦ 4.5 μm. δ: Assuming that the amount of the core pin protruding from the upper surface of the V groove when set is

[0026]

[Equation 1]

This variation (δ _max −δ _min )
Is a factor that causes variations in ferrule eccentricity in the direction perpendicular to the fibers caused by the V-groove processing. ] Here, E _U: upper die modulus, E _L: lower mold modulus, E _P: core pin modulus, [nu _U: upper die Poisson's ratio, [nu _L: lower mold Poisson's ratio, [nu _P: core pin Poisson's ratio, lambda _U: approaching of the upper die and the core pin, lambda _L: close amount of the lower mold and the core pin, W _U: load of the upper mold and the core pin, W _L: When the load of the lower mold and the core pin, contact Hertz From theory

[0028]

[Equation 2]

From the balance of forces, W _U = 2W _L sin α / 2 (3) Geometrically, Δ = λ _L / sin α / 2 (4) δ = λ _L / sin α / 2 + λ _U (5) Solving this,

[0030]

[Equation 3] Becomes This denominator is a positive number greater than 1, so

[0031]

Equation 4] δ-Δ = Cδ (0 < C <1) ie, V groove processing accuracy, the variation ([delta] _max -
δ _min ) variation of pin center after mold clamping

[0032]

Equation 5] _{(δ-Δ) max - (} δ-Δ) min becomes smaller. On the other hand, if there is a gap during mold clamping, the pins play and the variation increases, so it is effective to make the diameters of all the core pins larger than the diameter of the inscribed circle of the V groove.

However, if the pin is tightened too much at the time of mold clamping, the shape of the fiber hole of the ferrule and the core pin are deformed so that the pin is no longer a perfect circle. Although this prevents the fiber from passing through, a larger core pin must be used to pass the fiber, which is an unfavorable factor because it causes an eccentricity of the fiber when mounting the fiber.

That is, since the pin surely deforms the V groove, its value is preferably set to a sufficiently small range of 0.5 to 4.5 μm. Of course, this must all be established at the optical connector molding temperature.

When the longitudinal elastic modulus of the core pin is made larger than the longitudinal elastic modulus of the lower die, the amount of deformation of the core pin diameter with respect to the difference between the same core pin diameter and the diameter of the inscribed circle of the V groove of the lower die and the space formed by the upper die. Can be made smaller. That is, the roundness of the fiber hole of the molded product can be improved.

Therefore, the fiber can be passed through with a thinner core pin diameter, which is preferable. The material used for the upper mold ^{_{(1-ν U 2) /}} E U a material used for the lower die (1-[nu
_When it is smaller than _L ² ) / E _L , two items of the denominator of the equation (6) become small, and therefore Δ becomes large with respect to δ.

That is, the variation of the pin center after mold clamping

(6) (δ−Δ) _max − (δ−Δ) _min becomes small. Therefore, such a combination is preferable.

In this case, since the upper die is deformed at the portion where the core pin and the die contact each other, only the portion that abuts the upper die pin and a part of the periphery are (1-ν _U ² ) / E _U It is enough to use a small material.

A molding method for utilizing these characteristics is as follows.
It is possible to obtain a ferrule for a multi-fiber optical connector by injecting resin into the cavity of a mold that is clamped while deforming the V groove of the lower mold, the upper mold, and the core pin until the upper mold and the lower mold are completely closed. preferable"

[0040]

The present invention is illustrated by the following examples, which do not limit the scope of the invention. Figure 1
It is a schematic diagram which shows the process of manufacturing the ferrule for multi-core optical connectors using the metal mold | die for manufacturing multi-core optical connector ferrules according to the Example of this invention.

FIG. 2 shows the dimensional relationship of the lower V groove, the upper die and the core pin of FIG. In practice, the same lower mold was used, and after conducting an experiment of a comparative example, the upper surface of the lower mold was about 3 μm.
The experiment of the example was carried out after m-lap polishing. 1 is shown in FIG.
Same as the above, only the part corresponding to the V groove and the molding pin of the lower mold of the upper mold is another part 113. The material of each mold is;

[0042]

[Table 1] Also, the physical properties are:

[0043]

[Table 2] Is.

All the values shown in FIG. 2 are dimensions at a molding temperature of 180 ° C. The V-groove has an angle of 60 °. An 8-core connector was used. In the evaluation, 20 ferrules were molded in each of the comparative example and the example, and the evaluation was made in Table 3 below based on the fiber hole arrangement of all 160 cores and the eccentricity variation in the direction perpendicular to the fiber hole (this eccentricity direction is referred to as y eccentricity). ).

[0045]

[Table 3]

As described above, by making the diameter of the inscribed circle of the mold pin smaller by 0.5 μm to 4.5 μm than the diameter of the molding pin, the direction perpendicular to the fiber hole arrangement of the ferrule for multi-core connector is obtained. The eccentricity variation of can be reduced.

Next, φ1 is inserted into the ferrule hole of the embodiment.
It was passed through a gauge pin of 25.5 to φ126.4 μm. (N = 16 because each 2 ferrules have 8 cores)

[Table 4]

As described above, the gauge pin having a larger diameter can be inserted into the cemented carbide having a large longitudinal elastic modulus of the core pin. The coefficient of thermal expansion of SUS440 is larger, and it is about 0.1μ at 180 ℃.
It should have been thicker. It is considered that this is because the cemented carbide has a longitudinal elastic modulus of 2.7 times, so that the deformation is small and the fiber hole is close to the perfect circle center.

On the contrary, in order to pass the same diameter fiber,
Since the fiber can be passed through with such a small core pin diameter, it is expected that the variation when the fiber is passed through the ferrule will be small.

[0050]

As described above, according to the present invention, it is possible to reduce the eccentricity variation in the direction perpendicular to the arrangement of the fiber holes of the super-multicore connector. Also, by using a material having a higher longitudinal elastic modulus than the material of the mold, the pin can be made to pass through the fiber with a thinner core pin.

Therefore, the arrangement of the holes of the ferrule and the arrangement of the fibers when the fibers are attached become small. In the multi-core connector, it is a necessary condition to make a low-loss connector that the arrangement and diameters of the fibers do not vary. Therefore, by using the method of the present invention, a multi-core connector having a lower loss than before can be made.

[Brief description of drawings]

FIG. 1 is a schematic view showing a structure of a mold for manufacturing a multi-fiber optical connector ferrule according to an embodiment of the present invention.

FIG. 2 is a view showing a dimensional relationship among a lower V groove, an upper mold, and a core pin of FIG.

FIG. 3 is a schematic view showing the structure of a conventional ferrule manufacturing die for a multi-fiber optical connector.

FIG. 4 is a schematic view showing an appearance of a ferrule for a multi-fiber optical connector.

FIG. 5 is a schematic view showing a structure of a multi-fiber optical connector.

[Explanation of symbols]

1 clamp 2 Tape-shaped optical fiber 100 ferrules 101 pores 102, 103 (multi-core) optical connector (ferrule) 104 Mating or guide pin 105 guide hole 106 Lower mold 106a V groove 107 Upper mold 107a Resin passage (flow passage) 108, 109 core pins 110 slider 101 Pore for inserting optical fiber 111 V groove (min) 112 body 113 Other components

Continuation of the front page (56) Reference JP-A-2-256009 (JP, A) JP-A-4-347605 (JP, A) European Patent Application Publication 514923 (EP, A1) (58) Fields investigated (Int .Cl. ⁷ , DB name) B29C 45/26 G02B 6/36 G02B 6/40

Claims (4)

(57) [Claims] 1. A ferrule manufacturing mold for molding a ferrule for a multi-fiber optical fiber connector, which has a hole for mounting a large number of optical fibers and a hole for mounting a guide pin for connecting ferrules to each other. Is a lower mold having a plurality of V-grooves for positioning the core pin for forming the optical fiber mounting hole and the guide pin mounting hole, an upper mold combined with the lower mold, and a core pin holding the upper mold. Manufacture of a ferrule for a multi-fiber optical connector, comprising a slider that is inserted into a cavity formed by a mold and the lower mold, and the core pin is positioned along the V groove of the lower mold. In the metal mold for use in molding, for all of the V grooves, the diameter of the inscribed circle at the mold temperature during ferrule molding in the space formed when the V grooves of the upper mold and the lower mold are clamped is the flap of the core pin. A die for manufacturing a ferrule for a multi-fiber optical connector, characterized in that it is made smaller than the diameter at the molding temperature by 0.5 μm to 4.5 μm. 2. The mold for producing a ferrule for a multi-fiber optical connector according to claim 1, wherein the longitudinal elastic modulus of the material used for the core pin is larger than the longitudinal elastic modulus of the material used for the lower die. A mold for manufacturing ferrules for multi-fiber optical connectors. 3. The ferrule manufacturing die for a multi-fiber optical connector according to claim 1 or 2, wherein (1-ν ² ) / E of the material used for the lower die is more than (1-) of the material used for the upper die.
characterized in that ν ² ) / E is smaller.
Mold for manufacturing ferrules for multi-fiber optical connectors. (However, E: longitudinal elastic modulus, ν: Poisson's ratio) 4. A plurality of Vs for positioning a core pin for forming an optical fiber mounting hole and a guide pin mounting hole.
A lower mold having a groove, an upper mold to be combined with the lower mold , and a core pin are inserted into a cavity formed by the upper mold and the lower mold , and the core pin is a V groove of the lower mold. Along
The mold, which is composed of the slider positioned by mounting the mold, is attached to the molding machine, the mold is clamped, resin is injected into the cavity of the mold, and the holes for mounting the optical fibers with a large number of fibers and the ferrules are joined together. In a method of manufacturing a ferrule for a multi-fiber optical connector having a hole for attaching a guide pin, a ferrule molding of a space formed when the upper and lower V-grooves are clamped for all V-grooves of the lower mold. The die is configured such that the diameter of the inscribed circle at the die temperature at that time is smaller than the diameter of the core pin at the ferrule molding temperature by 0.5 μm to 4.5 μm. The core pin is set in the V groove, and the upper mold is clamped while deforming the V groove of the lower mold, the upper mold, and the core pin until the upper and lower molds are completely closed, and the mold cavity is clamped. Resin is injected into the part And, characterized in that to obtain a multi-fiber optical connector ferrule, a manufacturing method of multiple-core optical connector ferrule.