JP2014124904A - Mold for molding lens for optical communication, lens for optical communication and molding method of lens for optical communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for molding a lens for optical communication, a lens for optical communication and its molding method in which molding performance is improved and product quality is improved.SOLUTION: Generally, a lens cavity LC has a big volume, and resistance received by a plastic material (A) flowing inside it is smaller than resistance received by a plastic material (B) flowing inside a leg-part cavity SC. Therefore, by mounting an air exhausting path AE at a position facing the flow of the plastic material (A), the air inside the leg-part cavity SC can be expelled quickly through the filled plastic material (A), resulting in improvement of filling efficiency.

Description

  The present invention is used for optical communication, for example, a mold for forming a lens for optical communication that couples light from an optical element such as a semiconductor laser to an optical fiber or a light receiving element, a lens for optical communication, and an optical communication The present invention relates to a lens molding method.

  In optical communication or the like, a lens for optical coupling is used for efficient optical coupling between a semiconductor laser or a light receiving element and an optical fiber. By the way, in the conventional lens for optical coupling, the structure which mainly supports a glass lens with a stainless steel leg part is widely used. However, a glass lens having an aspheric surface is generally expensive, and there is a problem that a significant cost is incurred due to a process of assembling with a leg portion made of different materials. Therefore, as shown in Patent Document 1, a plastic leg-integrated lens that can be easily molded with high accuracy and enables mass production has been developed.

JP 2007-183565 A JP 2008-213397 A

  By the way, in general plastic lens molding, a minute gap (air vent) is provided on the mating surface of the mold and on the opposite side of the gate portion, and as the plastic is filled, air in the cavity is formed on the mating surface. By discharging to the outside through the gap, the filling efficiency of the plastic flowing into the cavity from the gate portion is enhanced.

  Moreover, when a cavity is comprised from several components, the function of an air vent is given by letting air escape from the clearance gap between components. A gap is necessary to allow air to escape, but if there is a gap, it can cause burrs. The maximum width of the air vent is limited to several μm to several tens of μm so that burrs do not occur or become small enough not to hinder product assembly even if burrs occur. There are many.

  However, it has been found that there is a problem when an air vent used in conventional plastic lens molding is applied to molding of a plastic leg-integrated lens as shown in Patent Document 1. Such a problem will be described. A leg-integrated lens used for optical communication is generally cylindrical and has a complicated shape. More specifically, in FIG. 1, a cavity CT, which is an internal space surrounded by a mold, is composed of a lens cavity LC that transfers a lens part and a leg cavity SC that transfers a leg part. A part (A) of the material flowing in from the side surface of the cavity CT through the gate part GT flows from above into the leg cavity SC across the axis of the lens cavity LC (the optical axis of the lens part to be transferred). To the point P farthest away from the gate. On the other hand, another part (B) of the material that has flowed in from the side surface of the cavity CT through the gate part GT goes around the leg cavity SC and goes to the point P farthest from the gate part.

  Then, it turned out that air accumulates in the side far from the gate part GT of cavity CT, and obstructs filling of a plastic material. That is, since the air in the cavity CT is not sufficiently removed, the plastic material that has entered from the gate part GT is not completely filled, and is located on the opposite side of the gate part GT and not in the final filling part at the end of the leg cavity. The transfer portion (VC in FIG. 2 (a)) is generated, or the air that has lost its escape is compressed in the cavity CT and becomes high temperature, so that the plastic material is heated and deteriorated, so-called gas burning occurs, resulting in poor appearance quality of the product. The trouble that became. In particular, in the case of a plastic lens used for optical communication, the end surface of the leg is often used as an adhesive surface for other parts, so if an untransferred part occurs, it may originally be a small-diameter lens. Even a small adhesion area will become even smaller. In addition, optical communication lenses may be sealed to extend the life of internal optical elements, but if untransferred parts exist, the sealing ability will be weakened and reliability will be reduced. There is a problem of doing.

  On the other hand, as shown in Patent Document 2, in order to evacuate the air in the cavity, a gap is formed to evacuate the air when the molds are combined, or air is vented by an air vent on the side opposite to the gate. The technology is known. However, even if a gap or air vent is provided at the outer edge of the lens cavity, the air accumulated at the end of the leg cavity cannot be removed.

  The present invention has been made in view of such problems, and provides a mold for molding a lens for optical communication and a lens for optical communication capable of improving moldability and improving product quality. Objective.

The mold according to claim 1 is a mold for molding a lens for optical communication made of plastic that collects a light beam emitted from an optical element or an optical fiber,
A first mold for forming a cavity for forming a cylindrical leg portion extending from the periphery of the lens portion of the lens; and an optical surface opposite to the leg portion in the lens portion of the lens A second mold for transferring
In the first mold, across the optical axis of the lens to be molded, on the transfer surface that forms the end surface of the leg portion on the side opposite to the gate portion that flows the plastic material into the cavity, An air escape passage that communicates the cavity and the outside is provided.

  According to the present invention, in the first mold, an end surface of the leg portion is formed on the side opposite to the gate portion where the plastic material flows into the cavity with the optical axis of the lens to be molded interposed therebetween. Since an air escape path that communicates the cavity and the outside is provided on the transfer surface, the air in the cavity can be effectively vented through the air escape path using the flow of the plastic material. it can.

  In particular, referring to FIG. 1, the lens cavity LC is generally large in volume, and the resistance received by the molten plastic material (A) flowing therethrough is the resistance of the plastic material (B) flowing in the leg cavity SC. Less than the resistance you receive. Therefore, by providing the air escape passage AE at a position opposite to the flow of the plastic material (A), the air in the leg cavity SC can be quickly expelled by the filled plastic material (A), and the filling efficiency is improved. Rise. The “transfer surface opposite to the gate portion where the plastic material flows into the cavity across the optical axis of the lens to be molded” refers to the lens transferred and formed by the cavity CT in FIG. A boundary BD is defined as a line of intersection between a surface PL perpendicular to the perpendicular line drawn from the center CN of the gate portion GT with respect to the optical axis OA and including the optical axis OA of the lens and the transfer surface BP forming the end surface of the leg portion. The transfer surface BP (hatching region) on the opposite side of the gate portion GT from that. The “center of the gate portion” refers to the center of the surface where the gate portion GT and the cavity CT intersect.

  The mold according to claim 2 is the invention according to claim 1, wherein the air passage includes an optical axis of the lens formed by the mold, and a surface passing through a center of the gate portion. , And provided at a place other than the position intersecting with the transfer surface.

  As described above, referring to FIG. 1, the flow of the plastic material (A) passing through the lens cavity LC is relatively strong. Therefore, depending on the shape of the molded lens, the flow is too strong. There is a possibility that the plastic material may directly enter the air escape path AE and remain as a burr after the plastic material is cured. In particular, the end surface of the leg portion of the lens may be used as a reference surface for attachment with other components. However, if burrs remain on the end surface of the leg portion, it takes time to remove this. Therefore, in the present invention, the air passageway includes the optical axis of the lens formed by the mold, and a surface passing through the center of the gate portion intersects the transfer surface (in FIG. 1, By providing a line segment connecting the point P farthest from the gate part GT and the center CN of the gate part GT at a place other than the line LN projected onto the transfer surface BP in the optical axis direction, the air escape path AE It is possible to suppress the occurrence of burrs by suppressing the direct entry of plastic material.

  The mold according to claim 3 is the invention according to claim 1 or 2, wherein the air passage includes an optical axis of the lens formed by the mold and passes through a center of the gate portion. When the angle on the surface perpendicular to the optical axis formed by the position where the surface intersects the transfer surface and the optical axis is 0 degree, the range around ± 80 degrees around the optical axis. At least two, and the air escape passages are provided on both sides of the + side and the − side across 0 degree.

  In FIG. 1, the 0 degree position of the transfer surface refers to a location on a line LN that passes through the point P farthest from the gate portion GT on the transfer surface BP, and the + side refers to FIG. Is the clockwise angle, and the minus side is the counterclockwise angle. Since the leg shape is cylindrical, the plastic material (A) passing through the lens cavity LC is positioned at 0 degree earlier on the transfer surface than the plastic material (B) passing through the leg cavity SC. Therefore, after the preceding plastic material (A) reaches the transfer surface BP, it is divided into two forks, and the delayed plastic material (B) is attacked, and as shown in FIG. There is a possibility that an untransferred portion VC of the plastic material sandwiched between the plastic material (A) and the plastic material (B) may occur in the direction of ± 45 degrees across the position. In this case, even if the air vent is provided only at the 0 degree position, the plastic material (A) reaches that part first, so the plastic material hardens while the air pushed in the direction of ± 45 degrees cannot escape. there's a possibility that. Therefore, the air escape path is provided on the + side and the − side of ± 80 degrees centering on 0 degree, thereby suppressing the untransferred portion of the plastic material (see FIG. 2C). . Preferably, the air escape path is provided within a range of ± 60 degrees, more preferably between −20 degrees to −60 degrees and between +20 degrees to +60 degrees.

  According to a fourth aspect of the present invention, there is provided the mold according to any one of the first to third aspects, wherein an opening is provided in a transfer surface that forms an end surface of the leg portion, and the opening is relative to the optical axis direction. A movable pin is accommodated, and the air passage is formed between the opening and the pin.

  In the case of a leg-integrated lens to which the present invention is applied, there is a risk that the leg part has a high resistance to release, and the leg part may be broken at the time of releasing. Therefore, a pin can be protruded from an opening provided in a transfer surface that forms an end surface of the leg, and the leg is pushed out from a mold by protruding the pin in the optical axis direction from the opening at the time of mold release. By doing so, it is possible to easily release the lens. Thus, the transfer surface with a small area can be used effectively by using both the pin protrusion opening and the air escape path. Further, by adjusting the size of the pin and the opening, the amount of burr generated and the amount of air escape can be adjusted as appropriate.

  According to a fifth aspect of the present invention, in the invention according to the fourth aspect, an annular convex portion is provided on the transfer surface around the opening.

  An annular concave portion is formed on the end surface of the leg portion of the lens molded by the mold provided with the annular convex portion. Therefore, even if the gap between the opening and the pin is large and the plastic material protruding from the gap is hardened and a large amount of burr is generated, it remains in the recess and protrudes from the end surface of the leg. This can further reduce the possibility of an obstacle when the end face of the leg is used as a reference plane.

  According to a sixth aspect of the present invention, in the invention according to the fourth or fifth aspect, the cross section of the opening and the pin is circular.

  By making the cross section of the opening and the pin circular, both can be formed with high accuracy, so that the gap is reduced and the generated burr can be reduced.

  A metal mold according to a seventh aspect is characterized in that in the invention according to any one of the first to sixth aspects, a plurality of the air passages are provided.

  By disposing a plurality of the air passages in a distributed manner, the filling efficiency of the plastic material can be improved. The number of air escape paths is preferably 3 to 6, and it is desirable to arrange them at regular intervals. In addition, if an opening for pin protrusion is provided in the vicinity of the gate part, mold release can be supported on the gate part side where the release resistance tends to increase, but in that case, the performance of the pin protrusion opening as an air escape path is improved. It is desirable to make it almost zero. In addition, by doing so, the air can efficiently escape from the final filling portion.

  According to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the air escape passage communicates with an air suction means.

  By connecting the air escape passage to the air suction means, air can be quickly extracted from the cavity of the mold through the air escape passage, and the filling efficiency of the plastic material can be further increased.

  According to a ninth aspect of the present invention, in the invention according to any one of the first to eighth aspects, the position of the gate portion in the optical axis direction and the position of the lens portion in the optical axis direction are at least partially. It is characterized by being the same.

  This can simplify the mold structure. In addition, it is preferable that the ratio between the length of the leg portion of the lens and the depth of the gate portion is 2.5: 1 to 1.5: 1 because gate cutting can be easily performed and filling efficiency is increased.

  The mold according to claim 10 is the invention according to any one of claims 1 to 9, wherein the central position of the gate portion is 70% to 90% of the length of the leg portion from the end surface of the leg portion. It exists in the position.

  An optical communication lens according to an eleventh aspect is formed from the mold according to any one of the first to tenth aspects.

The method for molding a lens for optical communication according to claim 12, wherein the lens for optical communication has a lens portion and a cylindrical leg portion extending from the periphery of the lens portion. The mold is closed by closing the first mold that forms the cavity for molding the cylindrical leg and the second mold that transfers the optical surface opposite to the leg of the lens part, A mold closing step of forming a cavity for molding the lens;
A molding step of molding a molded product by filling a plastic material into the cavity;
A mold opening step of opening the mold after the molding step;
A projecting step for projecting the molded product formed by moving the pin relative to the mold in the direction of the optical axis after the mold opening process to release the mold from the mold, and
Of the transfer surface forming the end surface of the leg portion in the first mold, the cavity on the opposite side to the gate portion including the optical axis of the lens to be molded and flowing the plastic material into the cavity The pin is accommodated in the opening, and the gap between the pin and the opening serves as an air escape passage through which air in the cavity is released.

  The air escape path through which the air in the cavity escapes includes the optical axis of the lens to be molded out of the transfer surface forming the end face of the leg portion in the first mold, and the plastic material flows into the cavity. Since it exists in the opposite side to a gate part, the air of a leg part cavity escapes suitably.

  The method for molding a lens for optical communication according to claim 13 is the invention according to claim 12, wherein the opening includes the optical axis of the lens molded by the mold and passes through the center of the gate portion. The surface is provided in a place other than the position where the surface intersects the transfer surface.

  Referring to FIG. 1, since the flow of the plastic material (A) passing through the lens cavity LC is relatively strong, depending on the shape of the lens to be molded, the flow is too strong, and the air escape path AE There is a risk that the plastic material may directly enter and remain as burrs after the plastic material is cured, but the surface including the optical axis of the lens formed by the mold and passing through the center of the gate portion is the transfer. By providing it at a place other than the position that intersects the surface, such a problem can be reduced, and it is not necessary to remove burrs.

  The method for molding a lens for optical communication according to claim 14 is the invention according to claim 12 or 13, wherein the opening includes an optical axis of the lens molded by the mold, and the center of the gate portion. When the angle on the surface perpendicular to the optical axis formed by the position where the surface passing through the surface intersects the transfer surface and the optical axis is 0 degree, the range from 0 degrees to +80 degrees around the optical axis And at least one each in the range of -80 degrees to 0 degrees.

  As a result, when the plastic material is filled into the cavity, the air escapes from the gap between the opening and the pin provided in the range of 0 ° to + 80 ° and the range of −80 ° to 0 ° on the transfer surface. Further, after the mold is opened, the molded product can be released by projecting the end face of the leg with a pin, so that the possibility that an untransferred area is generated can be reduced, and the moldability and product quality can be improved.

The optical communication lens according to claim 15 is a plastic optical communication lens for condensing a light beam emitted from an optical element or an optical fiber,
The lens includes a lens portion for collecting a light beam emitted from an optical element or an optical fiber, a cylindrical leg portion extending from the periphery of the lens portion, and a gate cut trace existing on an outer peripheral side surface of the leg portion. And
A protruding trace for releasing the lens from the mold is provided on the side opposite to the gate cut mark and on the end surface of the leg portion with the optical axis of the lens interposed therebetween.

  According to the lens, when the plastic material is filled in the cavity during molding of the lens, the air pushed out to the leg portion from the gap for sliding the protrusion pin around the protrusion pin is released. Therefore, the lens has almost no untransferred portion. Further, since the leg end surface is projected, this lens is hardly broken at the base of the leg during molding.

  The lens for optical communication according to claim 16, in the invention according to claim 15, wherein the protruding trace includes a plane that includes an optical axis of the lens and passes through a center of the gate cut trace, and an end face of the leg portion. It exists in places other than the position where and intersect.

  Since there is no protruding trace at the position where the surface passing through the center of the gate cut trace including the optical axis of the lens intersects the end face of the leg, there is almost no burr around the protruding trace in this lens. Not done.

  The lens for optical communication according to claim 17 is the lens according to claim 15 or 16, wherein the protrusion trace includes a plane that includes an optical axis of the lens and passes through a center of the gate cut trace, and the leg. When the angle on the plane perpendicular to the optical axis formed by the position at which the end face intersects the optical axis is 0 degree, the range of 0 degree to +80 degree and -80 degree to 0 degree around the optical axis At least one each in the range of degrees

  This lens has a cylindrical leg when the plastic material is filled into the cavity during molding, and it is on the leg end face against the air trap that is generated just because the resin flows in from the gate. Since air has escaped from the gap between the opening and the pin provided in the range of 0 ° to + 80 ° and in the range of −80 ° to 0 °, the lens has a high quality with almost no untransferred area. In addition, since the leg end face protrudes from at least two places, this lens hardly breaks at the base of the leg during molding.

  According to the present invention, it is possible to provide a mold for molding a lens for optical communication capable of improving moldability and improving product quality, a lens for optical communication, and a molding method thereof.

It is a figure for demonstrating the principle of this invention, and is a perspective view which shows typically the cavity in a metal mold | die. It is a figure which shows the transfer surface of the metal mold | die which transfers the leg part end surface of a lens, and the plastic raw material (it shows by hatching) with which it is filled here. It is an optical axis direction sectional view of an optical communication module using a lens concerning this embodiment. It is a figure which shows the manufacturing process of the lens of this Embodiment. It is the figure which cut | disconnected the movable metal mold | die MM of FIG. It is a perspective view which shows the relationship between the nesting type BM and pin AM8. It is a figure which shows typically transfer surface AM5 of the movable metal mold | die concerning a modification. It is a part of sectional drawing of the movable metal mold | die concerning a modification. It is sectional drawing of the leg part of the lens transfer-molded by the movable metal mold | die concerning a modification. It is sectional drawing of the shaping | molding apparatus concerning another modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is a cross-sectional view in the optical axis direction of the optical communication module 10 according to the present embodiment. A chip mounting portion 13 is attached to the approximate center of a disk-shaped stem 12 having rod-shaped terminals 11 for feeding power, and a laser chip 15 as a light emitting element is attached to a side surface of the chip mounting portion 13 via a heat sink 14. ing. The laser chip 15 is connected to the terminal 11 via a wiring (not shown).

  A lens 20 is disposed so as to cover the outside of the laser chip 15. The lens 20 is made of plastic, and is integrally formed from a substantially cylindrical leg portion 21 and a lens portion 22 provided at an end portion of the leg portion 21. Since the lens 20 is made of plastic and the stem 12 is usually gold-plated, and it is difficult to weld the leg portion 21 of the lens 20 to the stem, the tip 21b of the leg portion 21 is bonded to the stem 12 so that the lens 20 20 is attached to the stem 12. Here, the tip 21b of the leg portion 21 serves as a reference surface for positioning the lens portion 22.

  The inner peripheral surface 21a or the outer peripheral surface 21c of the leg 21 is a cylindrical surface parallel to the optical axis. The lens unit 22 has an optical surface S1 on the laser chip 15 side and an optical surface S2 on the optical fiber 32 side. A roughened surface around the optical surface S2 is preferable because unnecessary light is diffused and the possibility of stray light can be reduced.

  A cylindrical stainless steel holder 30 with a slight gap is attached outside the lens 20 in the direction orthogonal to the optical axis so as to be welded to the stem 12. A cylindrical sleeve 31 having a smaller diameter is fixed to the tip of the holder 30, and a ferrule 32 into which the optical fiber FB is inserted is inserted therein. The end of the optical fiber FB faces the lens unit 22. ing.

  An operation of the optical communication module 10 of the present embodiment will be described. When power is supplied via the terminal 11, the laser chip 15 emits light, and the emitted light beam passes through the lens unit 22, is refracted by the refracting surface, and is condensed on the end surface of the optical fiber FB, and then in the optical fiber FB. Will be propagated.

  FIG. 4 is a diagram illustrating a process according to a lens manufacturing method suitable for the above-described embodiment. 4 includes the optical axis of the lens molded by the mold, and coincides with the plane passing through the center of the gate portion AM3. As shown in FIG. The circular through hole AM7 and the pin AM8 are formed on the side to be processed, but actually, as shown in FIG. 5, the circular through hole AM7 and the pin AM8 are not formed on the opposite side of the gate portion AM3. Further, hereinafter, the first mold is described as a fixed mold FM, and the second mold is described as a movable mold MM. Here, the fixed mold FM has a transfer surface FM1 for transferring the optical surface S2, and a flat mating surface FM3 around the transfer surface FM1.

  On the other hand, the movable mold MM that is movable with respect to the fixed mold FM has a main mold AM and a nested mold (sub mold) BM. The main mold AM includes a transfer surface AM1 for transferring the inner and outer circumferences of the leg portion 21, a transfer surface AM5 for transferring the end surface of the leg portion 21, a central circular opening AM2, and a gate for injecting a plastic material from the outside. Portion AM3, flat mating surface AM4 facing mating surface FM3, and narrow groove AM6 (depth 0.01 to 0.03 mm, width) communicating on the mating surface AM4 at the position facing gate portion AM3 on mating surface AM4 1 mm). While the length of the leg portion 21 is 2.6 mm, the depth of the gate portion AM3 in the same direction is 1.3 mm. The center position of the gate portion AM3 exists at a position of 70% to 90% of the length of the leg portion 21 from the transfer surface AM5 on which the end surface of the leg portion 21 is transferred.

  Since the gate portion AM3 is formed by the rectangular cross-section groove formed on the mating surface AM4 of the movable mold MM and the mating surface FM3 with the fixed mold FM, the mating surface FM3 can be a simple plane. This simplifies the structure of the mold. The gate portion AM3 communicates with a position corresponding to the outer peripheral surface of the leg portion 21, and is provided toward the lens portion 22 so as not to face a position corresponding to the inner peripheral surface of the leg portion 21. That is, at least a part of the gate portion AM3 overlaps the position in the optical axis direction with respect to the space (lens portion after molding) formed by the transfer surface FM1 and the transfer surface BM1 of the nested BM. A space formed by the transfer surface AM1 and the transfer surface AM5 corresponds to the leg cavity SC of FIG. The narrow groove AM6 and the mating surface FM3 of the fixed mold FM form a first air passage that communicates the cavity with the outside. However, the first air passage may not be provided.

  The cylindrical nesting mold BM is fitted to the circular opening AM2, is fixed to the main mold AM, and has a transfer surface BM1 for transferring the optical surface S1 at the tip. A space formed by the transfer surface BM1 and the periphery thereof and the transfer surface FM1 of the fixed mold FM and the periphery thereof corresponds to the lens cavity LC of FIG.

  FIG. 5 is a view of the movable mold MM shown in FIG. 4A taken along the line V-V and viewed in the direction of the arrow. The annular transfer surface AM5 is provided with three circular through holes (also referred to as openings) AM7 extending in the axial direction of the movable mold MM at equal intervals. The at least one circular through hole AM7 is desirably provided at a position overlapping the gate portion AM3 in the radial direction when viewed in the axial direction. In the vicinity of the gate portion AM3, when the molded lens is released, the release resistance is particularly likely to increase. Therefore, by extruding the lens with the pin AM8 provided in the vicinity thereof, the release property is further improved. As shown in FIG. 4, a cylindrical pin AM8 is inserted into the circular through hole AM7 so as to be relatively movable. The diameter of the pin AM8 is 0.005 to 0.07 mm, and a plastic mold steel, SKD61, SKH51, or the like can be suitably used, but is not limited thereto. A gap between the circular through hole AM7 and the cylindrical pin AM8 forms a second air escape path that connects the cavity and the outside. Further, since the second air escape path includes the optical axis of the lens molded by the mold and the surface passing through the center of the gate portion is provided at a place other than the position intersecting the transfer surface, It is possible to further suppress the possibility of occurrence.

  FIG. 6 is a perspective view showing the relationship between the nested BM and the pin AM8. The ends of the three pins AM8 are connected to a ring RG having a diameter larger than that of the nested BM. The nested mold BM moves as a movable mold MM integrally with the main mold AM, but the ring RG is moved so as to be able to advance and retreat in the axial direction independently by a known drive source (not shown). .

  The manufacturing process of the present embodiment will be described. First, as shown in FIG. 4A, the movable mold MM is clamped with respect to the fixed mold FM so that the mating surfaces FM3 and AM4 are brought into close contact with each other. . In this state, a molten plastic material (acrylic, PC, etc.) is injected into the internal cavity via the gate portion AM3. At this time, from the first air passage formed by the narrow groove AM6 and the mating surface FM3 of the fixed mold AM, and the second air passage formed by the gap between the circular through hole AM7 and the cylindrical pin AM8. Since the air in the cavity escapes to the outside, it is possible to increase the filling efficiency of the plastic material.

  Further, as shown in FIG. 4B, after the material is cooled, the movable mold MM is displaced so as to be integrally moved away from the fixed mold FM.

  Next, as shown in FIG. 4C, the pin AM8 is relatively moved so as to protrude from the main mold AM. Then, the end surface (bottom surface) of the leg portion 21 of the lens 20 which is a molded product is pushed out by the pin AM8 and can come out of the main mold AM stably without being broken. At this time, the mark pushed out by the pin AM8 remains on the lens. Thereafter, the molded product is removed from the transfer surface BM1, but since the gate GT ′ solidified in the gate portion AM3 is connected to the molded product, this is cut (C) in the step shown in FIG. Polish the cut surface. Further, since burr BR is generated according to the first air escape path and the second air escape path, this is cut and polished. Thus, the lens 20 can be obtained. However, polishing and burr cutting are not necessarily required. For example, when the burr is within the range of the design error, the burr need not be cut.

  FIG. 7 is a schematic view showing a mold transfer surface AM5 provided in a mold according to a modification, and shows positions of circular through holes AM7 and pins AM8. In the example of FIG. 7A, a plastic material to be filled is provided by providing a circular through hole AM7 as an air escape passage at a position (near 0 degrees) facing the flow of the plastic material (A) shown in FIG. By (A), the air in the leg cavity can be expelled quickly, and the filling efficiency is increased. Further, since only one pin AM8 is required, the configuration of the movable mold MM is simplified.

  In the example of FIG. 7B, in addition to the position (near 0 degree) facing the flow of the plastic material (A) shown in FIG. 1, a circular through hole AM7 as an air escape path is provided at a position of ± 45 degrees. Yes. Thereby, the air in the region sandwiched between the flow (A) and the flow (B) of the plastic material shown in FIG. 1 can be quickly discharged to the outside, and defects such as poor transfer of the plastic material and gas burn can be suppressed. . In particular, in the case of plastic lenses used for optical communications, it is possible to reduce the possibility of a decrease in adhesion area due to the occurrence of untransferred portions on the end surfaces of the legs, and the possibility of a decrease in sealing performance. A lens with high performance can be provided.

  In the example of FIG. 7C, four circular through holes AM7 are provided at intervals of 90 degrees in the circumferential direction. Thereby, the leg part of the lens as a molded product can be protruded with good balance by the pin AM8 at the time of mold release. However, the circular through hole AM7 provided at a position of ± 135 degrees may not be an air passage. In particular, when the flow of the plastic material (A) shown in FIG. 1 is too strong, if the circular through hole AM7 is provided at the 0 degree position, the burr extending from between the pins AM8 may become long. Thus, such a problem can be solved by not providing the circular through hole AM7 at the 0 degree position.

  In the example of FIG. 7D, five circular through holes AM7 are provided at intervals of 72 degrees in the circumferential direction. Thereby, in addition to being able to protrude the leg part of the lens as a molded product with a pin AM8 at the time of mold release, the region between the plastic material flow (A) and flow (B) shown in FIG. Air can be quickly discharged to the outside, and defects such as poor transfer of plastic materials and gas burns can be suppressed. However, the circular through hole AM7 provided at a position of ± 144 degrees may not be an air passage.

  FIG. 8 is a part of a sectional view of a movable mold according to another modification. FIG. 9 is a cross-sectional view of a leg portion of a lens transferred and molded by a movable mold according to another modification. In this example, an annular projection AM9 is formed on the transfer surface AM5 around the circular through hole AM7. Other configurations are the same as those of the above-described embodiment. The pin AM8 may protrude from the convex portion AM9 or may be flush.

  By transferring the annular convex portion AM9 to the lens leg 21 at the time of lens molding, an annular recess 21d is formed at the tip 21b of the lens leg 21 as shown in FIG. Therefore, even if the plastic material protruding from the gap between the circular through hole AM7 and the pin AM8 is cured to form the burr BR, it remains in the recess 21d and does not protrude from the tip of the leg 21. Thus, it is possible to prevent an obstacle when the tip of the leg portion 21 is used as a reference plane.

  FIG. 10 is a cross-sectional view of a molding apparatus according to yet another modification. In this example, in contrast to the above-described embodiment, a sealed chamber CB is provided on the back side of the movable mold MM, and the inside of the chamber CB is evacuated by a negative pressure pump VP as an air suction means. Is different. Other configurations are the same as those of the above-described embodiment.

  According to this example, the inside of the chamber CB is evacuated by the negative pressure pump VP, so that the inside of the cavity is sucked through the gap between the nested BM and the circular opening AM2, and the circular through hole AM7 and the cylindrical shape are formed. Since suction inside the cavity is performed through the gap between the pins AM8, the filling efficiency of the plastic material is further increased. Therefore, since the growth of burrs generated in the gap between the through hole AM7 and the cylindrical pin AM8 is also promoted, it is desirable to combine with the configuration shown in FIG.

  The present invention is not limited to the embodiments described in the specification, and other embodiments and modifications are apparent to those skilled in the art from the embodiments and ideas described in the present specification. It is. For example, the lens of the present invention may be used to collect light emitted from an optical fiber on a light receiving element.

DESCRIPTION OF SYMBOLS 10 Optical communication module 11 Terminal 12 Stem 13 Chip mounting part 14 Heat sink 15 Laser chip 20 Lens 21 Leg part 21a Inner peripheral surface 21b Tip 21c Outer peripheral surface 21d Recessed part 22 Lens part 30 Holder 31 Sleeve 32 Optical fiber 32 Ferrule AM Fixed mold AM Main Mold AM1 Transfer surface AM2 Circular opening AM3 Gate portion AM4 Matching surface AM5 Transfer surface AM6 Narrow groove AM7 Circular through hole AM8 Pin AM9 Protrusion BM Nested BM1 Transfer surface BR Burr CB Chamber FM Fixed mold FM1 Transfer surface FM3 Matching surface GT Gate part MM Movable mold VP Negative pressure pump RG Ring S1 Optical surface S2 Optical surface

Claims (17)

A mold for molding a lens for optical communication made of plastic that collects a light beam emitted from an optical element or an optical fiber,
A first mold for forming a cavity for forming a cylindrical leg portion extending from the periphery of the lens portion of the lens; and an optical surface opposite to the leg portion in the lens portion of the lens A second mold for transferring
In the first mold, the cavity is formed on the transfer surface that forms the end surface of the leg portion on the side opposite to the gate portion that flows the plastic material into the cavity with the optical axis of the lens to be molded interposed therebetween. A mold characterized by providing an air escape passage communicating with the outside.   The air escape path includes an optical axis of the lens molded by the mold, and a surface passing through the center of the gate portion is provided at a place other than a position intersecting the transfer surface. The mold according to claim 1.   The air escape path includes an optical axis of the lens formed by the mold, and a plane passing through the center of the gate portion is perpendicular to an optical axis formed by a position where the optical axis is intersected with the transfer surface. When the angle on the surface is 0 degree, at least two around the optical axis are provided in a range of ± 80 degrees around 0 degree, and both sides of + side and-side across 0 degree. The mold according to claim 1 or 2, wherein the air escape passage is provided in each of the molds.   An opening is provided in the transfer surface that forms the end face of the leg, and a pin that is relatively movable in the optical axis direction is accommodated in the opening, and the air passage is between the opening and the pin. The mold according to any one of claims 1 to 3, wherein the mold is provided.   The mold according to claim 4, wherein an annular convex portion is provided on the transfer surface around the opening.   6. The mold according to claim 4, wherein a cross section of the opening and the pin is circular.   The mold according to claim 1, wherein a plurality of the air escape paths are provided.   The mold according to any one of claims 1 to 7, wherein the air escape passage communicates with air suction means.   The mold according to any one of claims 1 to 8, wherein a position of the gate portion in the optical axis direction and a position of the lens portion in the optical axis direction are the same at least in part.   The metal mold according to any one of claims 1 to 9, wherein the center position of the gate portion exists at a position of 70% to 90% of the length of the leg portion from the end surface of the leg portion. .   A lens for optical communication, which is molded from the mold according to any one of claims 1 to 10. A method of forming a plastic optical communication lens having a lens portion and a cylindrical leg portion extending from the periphery of the lens portion, wherein a cavity for forming the cylindrical leg portion is formed. A mold closing step of forming a cavity for molding the lens by closing the mold of the first mold and the second mold for transferring the optical surface opposite to the leg portion of the lens portion;
A molding step of molding a molded product by filling a plastic material into the cavity;
A mold opening step of opening the mold after the molding step;
A projecting step for projecting the molded product formed by moving the pin relative to the mold in the direction of the optical axis after the mold opening process to release the mold from the mold, and
Of the transfer surface forming the end surface of the leg portion in the first mold, the cavity on the opposite side to the gate portion including the optical axis of the lens to be molded and flowing the plastic material into the cavity And an opening communicating with the outside, wherein the pin is accommodated in the opening, and a gap between the pin and the opening serves as an air escape passage through which air in the cavity escapes. Lens molding method.   13. The opening is provided at a place other than a position where a surface including an optical axis of the lens molded by the mold and passing through the center of the gate portion intersects the transfer surface. A method for molding a lens for optical communication as described in 1.   The opening is formed on a surface perpendicular to the optical axis, which is formed by a position where a surface passing through the center of the gate portion including the optical axis of the lens formed by the mold intersects the transfer surface. 14 or 13, wherein there are at least one each in the range of 0 ° to + 80 ° and the range of −80 ° to 0 ° around the optical axis when the angle is set to 0 °. A method for molding a lens for optical communication as described in 1. A lens for optical communication made of plastic that collects a light beam emitted from an optical element or an optical fiber,
The lens includes a lens portion for collecting a light beam emitted from an optical element or an optical fiber, a cylindrical leg portion extending from the periphery of the lens portion, and a gate cut trace existing on an outer peripheral side surface of the leg portion. And
For optical communication, characterized in that it has a protruding mark for releasing the lens from the mold on the opposite side of the gate cut mark and on the end face of the leg across the optical axis of the lens. lens.   16. The protrusion mark is present in a place other than a position where a surface passing through the center of the gate cut mark including the optical axis of the lens and the leg end surface intersect each other. The lens for optical communication as described.   The protrusion mark has an angle on a plane perpendicular to the optical axis, which is formed by a position where a surface passing through the center of the gate cut trace including the optical axis of the lens intersects the leg end surface and the optical axis. 17. The device according to claim 15, wherein at least one exists in the range of 0 ° to + 80 ° and the range of −80 ° to 0 ° around the optical axis when the angle is set to 0 °. Lens for optical communication.

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