JP3111004B2 - Injection mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for injection molding, and more particularly to a mold suitable for injection molding a ferrule.

[0002]

2. Description of the Related Art Ferrules are parts of optical fiber connectors used for connecting optical fibers. The connection of the optical fiber is performed by arranging a pair of ferrules and abutting a sleeve on both fitting portions. Therefore, the uniformity of the outer diameter of the fitting portion of the ferrule and the coaxial accuracy between the outer diameter and the insertion hole of the optical fiber greatly affect the connection loss of the optical fiber.

[0003] It has been proposed to integrally mold such a ferrule which is a hollow cylindrical product by injection molding. In injection molding, a molded product is obtained by filling a molten resin into a mold. However, even in a mold in which the runner and the gate are processed with high precision and the flow length of the mold is the same, due to factors such as the manufacturing accuracy of the mold, molding conditions, and the flow characteristics of the resin. In addition, the flow length of the resin varies at the gate before the cavity inflow (including the case where the runner is directly connected to the cavity and the gate is formally omitted).

In particular, in the injection molding of a ferrule, when a resin having a variation in the flow length of the resin is filled in the cavity, a core pin for forming a fine hole is tilted in a direction perpendicular to a central axis of the fine hole. Then, the fiber hole after the molding is bent or the hole position is shifted. In addition, since the filling density of the resin differs depending on each part of the ferrule, the outer diameter is deformed and the tip portion is tapered.
In this manner, not only does the cross-sectional shape and fiber hole of the fitting portion of the injection-molded ferrule become non-uniform,
Deteriorating the concentricity between the cross-sectional shape of the fitting part and the fiber hole,
This increases the connection loss of the optical fiber.

FIGS. 10 and 11 show the essential parts of an actual injection molding die for molding a conventional hollow cylindrical or solid cylindrical product. In each mold, gates 52 are formed at the tips of a plurality of runners 51 branched from a sprue 50, and a cavity 53 is filled with a molten molding material from each gate 52. The gate 52 shown in FIG. 10 is composed of two side gates, and the gate 52 shown in FIG. 11 is composed of a combination of a ring gate and a ring-shaped film gate. In each of the molds having the plurality of runners 51, the sprue 50 passes through the respective runners 51 to form the gate 52.
Are designed to be the same and are taken into consideration so that the cavity 53 is uniformly filled with the molten molding material. Each 54 indicates the position of the ejector pin.

However, strictly speaking, as described above, it is unavoidable that the flow length of the resin varies until it reaches the gate 52 before flowing into the cavity 53, so that a highly accurate product cannot be manufactured. Cannot be molded. In addition, in order to suppress the variation in the flow of the resin before flowing into the cavity 53, it is difficult to quantitatively grasp the allowance for deep engraving and polishing of the runner 51 and the gate 52, and it is very difficult to rework the mold. Have difficulty.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional technical problem.
It is as follows. The invention according to claim 1 has at least two runners connected to a cavity defined by at least two molds, and injects a molten molding material into a cavity provided with a pin at the center so that the holes are concentric. An injection mold for molding a hollow cylindrical product having a protruding member capable of increasing or decreasing a protruding length into a runner in a clamped state, and protruding the protruding member into a corresponding runner. Adjust the flow resistance by changing the length, and adjust the flow resistance of the runner.
The Rukoto constantly molten molding material is injected, an injection mold, wherein the molten molding material be flowed simultaneously <br/> towards the pin in the cavity from the runner. According to a second aspect of the present invention, each runner is provided with a protruding member.
2. The injection molding die according to claim 1 , wherein the projecting members of each runner are arranged at an equal distance from the center of the cavity.

[0008]

According to the first aspect of the present invention, when the mold that defines the cavity is new, test injection molding is performed, and the production accuracy of each runner and gate, that is, the deep engraving allowance,
Check the adequacy of polishing cost. That is, when the molten resin in the injection molding machine is injected, it is injected into the cavity through each runner and gate. Then, a hole is formed by a pin by the molten resin injected and filled in the cavity .
A hollow cylindrical product is formed.

The overall shape of the hollow cylindrical product thus formed , in particular, the manufacturing accuracy of the center axis of the hole formed by the pin is inspected. If the center axis of the hole is twisted or bent due to the flow pressure of the resin, the length of protrusion of the protruding member to the corresponding runner is increased or decreased.

As described above, in the runner in which the protruding member protrudes long, the resin flow path is narrow. Therefore, the flow resistance of the resin flowing through the runner is increased, and the same state as the flow length of the resin is increased. Thus, by adjusting the projecting length of the projecting member provided on the runner, the flow length of the resin reaching the cavity through the runner is adjusted to be substantially equal to the flow length of the resin flowing through the other runner. Can be.

After the length of the protrusion of the protruding member into the runner is appropriately increased or decreased, steady injection molding is performed.
As a result, resin having no flow variation is filled in the cavity, and a product in which the center axis position of the pin and thus the hole is accurate and straight can be formed. In addition, since the difference in resin filling density between each part of the product is reduced, deformation of the outer diameter of the product and tapering of the tip end hardly occur.

According to the second aspect of the present invention, each projecting member is
Each was placed equidistant from the center of the cavity. Thereby, since the adjustment amounts of the flow resistance obtained by changing the protruding lengths of the respective protruding members match, the work of adjusting the flow resistance becomes easy.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 7 show an embodiment in which the injection mold according to the present invention is applied to a ferrule injection mold. First, a ferrule which is a hollow cylindrical product will be described with reference to FIGS. The ferrule 1 is integrally formed of synthetic resin to form a cylindrical shape, and has an outer diameter of a small diameter having a tapered portion 1a whose diameter gradually decreases from one end (the left end in FIG. 6) toward one end. A fitting portion 1b formed of a cylindrical surface, a large-diameter flange-like portion 1c, a medium-diameter short cylindrical portion 1d, and a minimum-diameter cylindrical surface portion 1f are formed.
g, a tapered hole 1h gradually increasing in diameter toward the other end and a large-diameter thick hole 1i are formed concentrically. The thick hole 1i extends to the inside of the fitting portion 1b. A plurality (four in FIG. 7) of notches 1j in contact with the short cylindrical portion 1d are formed in the flange-like portion 1c at predetermined intervals. The fine hole 1g, the tapered hole portion 1h, and the thick hole 1i form an optical fiber insertion hole,
The optical fiber inserted from the side of the large hole 1i is bonded and fixed to the large hole 1i and the small hole 1g.

An injection mold for molding such a ferrule 1 will be described with reference to FIGS. The injection mold includes a fixed second mold 2 and a movable first mold 3 opposed to the second mold 2. As shown in FIG. 4, the second mold 2 includes a fixed mold plate 22a and a fixed mounting plate 22b.
And a sprue bush 22c for partitioning the sprue 30.

On the other hand, the first mold 3 defines a cavity A to be connected to the sprue 30 by being clamped to the second mold 2, and includes a movable mold plate 23a and a movable mount plate 23b.
, Receiving plate 23c, spacer block 23d, upper ejector plate 23e, lower ejector plate 23
f, and first and second ejector pins 26 and 28 which are arranged as shown in FIG. 1 and also function as projecting members. The first mold 3 is attached to a movable mold clamping plate (not shown), and is driven back and forth by a toggle type or direct acting type mold clamping device.

The cavity A includes a first cavity A1 and a second cavity A2 as shown in FIG. The first cavity A1 is formed in the second mold 2, and the ferrule 1
Along with defining a fitting portion 1b having a tapered portion 1a, small-diameter thin pins 13 for forming the pores 1g is first calibration
It protrudes from the second mold 2 as the center of the bitness A1 .
The second cavity A2 is formed in the first mold 3, and has a flange-like portion 1c of the ferrule 1 and a short cylindrical portion 1 serving as a holding portion.
d and the cylindrical surface portion 1f, and the tapered hole portion 1h
And thickness pins 12 of a large diameter for forming a large hole 1i is, the second calibration
It protrudes from the first mold 3 as the center of the bitness A2 .
Accordingly, the thick pin 12 has a tapered portion 12a whose tip portion is gradually reduced in diameter toward one end. In addition, the thick pin 12
Has a through-hole (not shown) in the direction of the central axis, into which the leading end of the thin pin 13 can be fitted at the time of mold clamping, and the leading end of the thin pin 13 has a thick pin. 12, and formed around the core pins supported at both ends in the cavity A. In addition, although one cavity A partitioned between the first mold 3 and the second mold 2 is formed, a plurality of cavities may be formed.

The runner 31 and the gate 32 connecting the sprue 30 and the cavity A are formed as shown in FIG. That is, a pair of main runners 31a extend from the sprue 30 in a U-shape, and branch runners 31b extending inward are formed at the front ends of the main runners 31a, respectively. 32 are connected. A pair of branch runners 3
1b is located on the extension of the diameter of each gate 32.
The cavities A are connected to the missing inner ends of the gates 32 which are substantially annular. The gates 32 on both sides, which are connected to the respective branch runners 31b and reach the cavity A in a branched state, are equidistant from each other. In the front view shown in FIG. 1, the sprue 30, the runner 31, the gate 32, and the cavity A are formed bilaterally symmetrically, and are connected to four connecting portions from one sprue 30 to the cavity A of both gates 32. The distances to reach each other are designed to be equal.

The molten molding material (resin) supplied from the sprue 30 is supplied to each main runner 31a and branch runner 31.
b and flows into the gates 32 respectively. Gate 32
The molten molding material that has flowed into the cavity is divided into two sides and flows in the circumferential direction, and is filled into the cavities A arranged at equal distances on both sides.

The first ejector pins 26 are connected to the respective main runners 3.
1a, and two second ejector pins 2
8 are arranged in each gate 32 by three. The second ejector pins 28 are arranged at the connection points with the respective branch runners 31b and at the center of the branch gate 32, that is, at the center between the branch runner 31b and the cavity A. Thus, the first and second ejector pins 2
6 and 28 are arranged equidistant from the center of the cavity A, respectively.

The first and second ejector pins 26, 2
Numeral 8 is movable in and out of each main runner 31a and gate 32, respectively. Thereby, the first and second ejector pins 2
In the mold clamped state, each of the main runners 31a and the gates 32 may project from the shortest length forming the same plane as the bottom surface of each of the main runners 31a and the gate 32 into the corresponding main runner 31a and the gate 32 by a predetermined length. It is possible.

That is, as shown in FIG. 3, the first ejector pin 26 has a main runner 31a having a semicircular cross-sectional shape.
To a retractable by a length L _1, the main runner 31 from the position where the front end surface is in contact with the bottom surface of the arcuate main runner 31a
a can be taken to a position (shown by a two-dot chain line) that enters deeply into a and largely blocks the flow path. Similarly, the second ejector pin 28, to the gate 32 having a rectangular cross-sectional shape as shown in FIG. 2, a retractable by a length L _2, the gate 32 from the position where the front end surface is in contact with the bottom surface of the gate 32 To a position (indicated by a two-dot chain line) where the flow path is deeply blocked and the flow path is largely blocked.

In the clamped state, the first and second ejector pins 2
The lengths L ₁ and L ₂ into which the corresponding main runners 6 and 28 enter the corresponding main runners 31a and the gates 32 are prepared in advance with a plurality of first and second ejector pins 26 and 28 having different lengths and exchanged with these. By doing so, it can be set freely. The protruding lengths L ₁ and L ₂ are determined based on the shortest state in which the main runners 31a and the gate 32 are in contact with the bottom surface and form the same surface as shown by solid lines in FIGS. The length is set long at a location where the molding material flows in quickly, and the flow resistance at each corresponding main runner 31a and gate 32 is increased.

Next, the operation will be described. The molding cycle of the injection molding apparatus is the same as that of an ordinary molding machine, and the steps of closing the mold, closing the mold, injecting, holding pressure, cooling, opening the mold, ejecting, etc., sequentially progress. With the mold clamped, the cavity A is defined, and the tip of the thin pin 13 is fitted into the tip of the through hole of the thick pin 12 to form a core pin.

From this state, the process moves to the injection step.
When the mold including the mold 2 and the first mold 3 is new, test injection molding is performed to determine the manufacturing accuracy of each of the runners 31 and the gates 32, that is, whether or not these deep engraving allowances and polishing allowances are appropriate. Confirm. That is, when the molten resin in the injection molding machine is injected from the nozzle to the sprue 30 in the second mold 2, it is injected from one end of the second cavity A2 through each runner 31 and the gate 32. The molten resin injected into the second cavity A2 flows right and left separately,
2, the flange-like portion 1c, the short cylindrical portion 1d, and the cylindrical surface portion 1f of the ferrule 1 are molded by the molten resin injected into the ferrule 1, and the molten resin injected into the first cavity A1 is formed by the molten resin. A fitting portion 1b having a tapered portion 1a is formed, and a fine hole 1g and a large hole 1i are formed at the center.

The overall shape of the ferrule 1 thus formed, in particular, the manufacturing accuracy of the fine pores 1 g is inspected. As shown by the dotted line in FIG. 5, when the thin pin 13 is twisted or bent by the flow pressure of the resin, the fine pore 1g is bent. Therefore, the main runners 31a and the gates 3 corresponding to the first and second ejector pins 26 and 28
The protrusion lengths L ₁ and L ₂ to ₂ are increased or decreased.

Specifically, the first and second ejector pins 2
The test is performed by setting the state of each of the main runners 6 and 28 in contact with the bottom surface of each main runner 31a and the gate 32. As a result, when a bend occurs in the pores 1g, the concavely curved portion of the bend (the convexly curved portion of the fine pin 13 in FIG. 5) causes the flow of the molten molding material into the cavity A to be slow, and In the convexly curved portion (the concavely curved portion of the thin pin 13 in FIG. 5), the flow of the molten molding material is fast, and accordingly, the first and second ejector pins 2
Replace 6,28 with a different length. The first and second
The replacement of the ejector pins 26 and 28 mainly depends on the pore size of 1 g.
The first and second ejector pins 26, 2 corresponding to the convexly curved portion of FIG. 5 (the concavely curved portion of the thin pin 13 in FIG. 5).
Replace 8 with a longer one. Thereby, the first and second ejector pins 26 and 28 arranged on the main runner 31a where the resin flow is fast are set longer than the other ejector pins, and flow resistance is given. FIG. 5 shows one of the second ejector pins 2.
8 shows a state where 8 is replaced with a long one.

In this manner, the first and second ejector pins 26, 2 disposed on each main runner 31a and the gate 32 are provided.
By adjusting the length of the ejector pin 2
In the main runner 31a and the gate 32 in which the main runners 31 and 32 are arranged, the ejector pins 26 and 28 are connected to the main runner 31 during mold clamping.
a and protruding from the bottom surface of the gate 32, the flow path of the resin is narrow. Therefore, the flow resistance of the resin flowing through the main runner 31a and the gate 32 is increased, and the same state as the flow length of the resin is increased. Thus, by adjusting the lengths of the ejector pins 26 and 28, the flow length and flow pressure of the resin can be adjusted to be substantially equal to the resin flowing through the other main runner 31a and the gate 32. it can. In addition, since the ejector pins 26 and 28 are disposed at the same distance from the center of the cavity A, the adjustment amounts of the flow resistance obtained by changing the protruding lengths of the respective ejector pins 26 and 28 match. Become. Therefore, the adjustment of the flow resistance becomes easy.

Thus, the first and second ejector pins 2
With the lengths of the main runners 31a and the gates 32 and 28 protruding into the gate 32 being appropriately increased or decreased, steady injection molding is performed. Thus, from each gate 32, the resin having no flow variation flows simultaneously toward the pins 12 and 13, and is filled in the cavity A, so that the core pin (1g) for forming the pores 1g is formed. It is possible to form a straight fiber hole having a precise hole position without the thin pin 13) falling down. In addition, since the difference in the resin filling density between the respective portions of the ferrule 1 is reduced, the bending of the center line can be suppressed, and the outer diameter is not deformed and the tip portion is hardly tapered. The concentricity between the outer diameter of the injection molded ferrule 1 and the fiber hole is very good, and sufficiently satisfies the performance as an optical fiber connector.

When the entire cavity A is filled with the molten resin B, the mold is opened after a pressure-holding and cooling step, and the molded product is taken out. That is, the first mold 3 is retracted, and the molded product in the cavity A is protruded by the first and second ejector pins 26 and 28 attached to the upper and lower ejector plates 23e and 23f. Note that, in parallel with the cooling step, a measuring step and an injection unit retreating step are performed in the injection molding machine.

In the ferrule 1 which is a molded product formed in this way, the outer diameter of the fitting portion 1b as well as the fine hole 1g is precisely molded. Thus, a pair of ferrules 1 each having an optical fiber (not shown) inserted therein are abutted against the fine holes 1g, the tapered holes 1h, and the large holes 1i, and a sleeve is externally fitted to the pair of fitting portions 1b to form an optical fiber connector. In this case, the connection state of the optical fiber is precisely obtained, and the connection loss is reduced.

The lengths of the first and second ejector pins 26 and 28 are determined experimentally as described above after preparing several ejector pins having different lengths.
As shown in (1), a mechanism capable of freely changing the length of the protruding member may be employed. FIG. 8 shows an example of a structure in which the lengths of the first and second ejector pins 26 and 28, which also function as projecting members, are variable. The ejector pin 29 has, at one end, a head 29a supported by the upper ejector plate 23e, an ejector pin main body 29c having a female screw 29b at the other end, and a pin member 29e having a male screw 29d at one end. By adjusting the amount of screwing of the male screw 29d to the female screw 29b, the ejector pin 29
The length of itself can be adjusted. Moreover, the length of the ejector pin 29 itself can be adjusted without removing the ejector pin 29 without removing the movable side mounting plate 23b and the receiving plate 23c.
It is possible to make use of the interval between. 29f
Indicates a non-rotating nut.

FIG. 9 shows a protruding member 34 which is arranged close to the first and second ejector pins 26 and 28, respectively. The projecting member 34 has a male thread portion 34 at one end.
It is formed by a pin member having a. And
The plurality of projecting members 34 are provided on the movable mold plate 23 of the first mold 3.
a and the receiving plate 23c are penetrated, and
a is screwed into the receiving plate 23c of the first mold 3. In this state, the leading end of each projecting member 34 is
a and the gate 32 so as to freely advance and retreat. Then
By adjusting the amount of screwing of the male screw portion 34a to the receiving plate 23c, the protruding length of the protruding member 34 corresponding to the runner 31 where the flow of the resin is fast, that is, the portion where the fine hole 1g is bent. Increase the size. At this time, the first and second ejector pins 26 and 28 remain in contact with the bottom surfaces of the main runners 31a and the gate 32 to form the same surface. The protruding length of the protruding member 34 is fixed by a nut 34c.

If the plurality of projecting members 34 are arranged at the same distance from the center of the cavity A, the flow resistance adjustment amounts obtained by changing the screwing amounts of the respective projecting members 34 coincide. Therefore, the work of adjusting the flow resistance becomes easy. Further, a plurality of protruding members 34 are disposed so as to penetrate the fixed-side mold plate 22a and the fixed-side mounting plate 22b of the second mold 2, and the male screw portion 34a is screwed to the fixed-side mounting plate 22b, and each protruding member 34 is protruded. The same operation can be obtained by allowing the distal end of the member 34 to move toward and away from the main runner 31a and the gate 32, respectively.

By the way, in the above embodiment,
Although the case where the hollow cylindrical product is a ferrule has been described, the present invention is also applicable to the case of injection molding other various hollow cylindrical products. Further, the ejector pins 26, 28, 29 or the projecting member 34 as the projecting member can be provided on the branch runner 31b.
The cavity A may be defined by at least two molds, and is not limited to the one defined by the first mold 3 and the second mold 2.

[0035]

As will be understood from the above description,
According to the mold for injection molding according to the present invention, the following effects can be obtained. In other words, it is possible to suppress variations in the flow of resin before flowing into the cavity without performing difficult reworking of the mold with quantitative understanding of the runner and gate deep engraving allowance and polishing allowance. Optimization is very easy. As a result, a hollow cylindrical product such as a ferrule can be obtained with high quality without causing a shape defect such as bending of a hole .

[Brief description of the drawings]

FIG. 1 is a front view showing an arrangement of a sprue, a runner, a gate, and a cavity of an injection mold according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is a sectional view showing the same injection molding mold.

FIG. 5 is a cross-sectional view partially omitted along the line VV in FIG. 1;

FIG. 6 is a sectional view showing the same ferrule.

FIG. 7 is a rear view showing the same ferrule.

FIG. 8 is a partial cross-sectional view showing a structural example of the ejector pin.

FIG. 9 is a cross-sectional view showing a main part of an injection mold including a protruding member according to another structural example.

FIG. 10 is a front view showing the arrangement of a sprue, a runner, a gate, and a cavity of a conventional injection mold.

FIG. 11 is a front view showing the arrangement of a sprue, a runner, a gate, and a cavity of a conventional injection mold.

[Explanation of symbols]

1: Ferrule (product), 1a: tapered portion, 1b: fitting portion, 1c: flange-shaped portion, 1d: short cylindrical portion, 1f: cylindrical surface portion, 1g: pore, 1h: tapered hole portion, 1i: thick Hole,
2: 2nd mold, 3: 1st mold, 12: thick pin, 13: thin pin, 26: 1st ejector pin (projecting member), 28:
Second ejector pin (projecting member), 29: ejector pin (projecting member), 31: runner, 34: projecting member, A:
Cavities, A1: first cavity, A2: second cavity.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyoshi Anaga 2-2-1 Fukuura, Kanazawa-ku, Yokohama-shi, Kanagawa Japan Steel Works Co., Ltd. (72) Koji Sato Inventor 3--19 Nishishinjuku, Shinjuku-ku, Tokyo No. 2 Nippon Telegraph and Telephone Corporation (72) Yoshito Shuto 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Shunichi Higashino 3-Nishi Shinjuku, Shinjuku-ku, Tokyo No. 19-2 Nippon Telegraph and Telephone Corporation (56) References JP-A-6-210669 (JP, A) JP-A-7-124989 (JP, A) JP-A 62-28516 (JP, U) Kaihei 4-109119 (JP, U) Japanese Utility Model Hei 5-76722 (JP, U) Registered utility model 3003711 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/26 -45/44

Claims (2)

(57) [Claims] 1. A semiconductor device comprising: at least two runners connected to a cavity defined by at least two molds ;
Molten molding material into the cavity provided by injection of the holes
An injection mold for molding a hollow cylindrical product having a concentric core, wherein a protruding member capable of increasing or decreasing a protruding length into a runner in a mold-clamped state is provided, and a protruding member in a corresponding runner is provided. the flow resistance adjusted decrease by changing the protrusion length of the La
Melt molding material constantly with the flow resistance of the
Injection mold by Rukoto is emitted, characterized in that the molten molding material from the runner to flow simultaneously towards the pin in the cavity a. 2. The injection mold according to claim 1 , wherein each runner is provided with a projecting member, and the projecting member of each runner is arranged at an equal distance from the center of the cavity.