JP2019177575A - Lens molding mold - Google Patents

Abstract

To provide a technology for improving molding accuracy in a lens molding mold.SOLUTION: A movable core 200 includes a first nest 210 and a second nest 220. The second nest 220 is fixed to a small-diameter through hole 212 formed in the first nest 210 by shrink fitting, and a tip of the second nest 220 protruding from the small-diameter through hole 212 is a lens molding part 221 molding a lens surface on one side. On a surface that is a parting line with the first nest 210 and the movable core 200, a spigot structure is formed by fitting a spigot convex part and a spigot concave part 290 together.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a lens molding die, and more particularly to a lens molding die for molding a plastic lens.

  In the recent camera market, demands for in-vehicle sensing cameras, high-pixel surveillance cameras, and the like are increasing, and there is a demand for cameras that are smaller but have higher performance. A plastic lens manufactured by injection molding is often used for a lens unit used in such a camera. In order to increase the molding accuracy of the plastic injection mold, it is necessary to keep the tolerances of the parts constituting the mold as small as possible. In particular, in a nesting mold, it is necessary to fix the nesting so that an error does not occur in the position of the nesting due to the clearance provided in the nesting housing portion, and various techniques have been proposed (for example, see Patent Document 1).

JP 2017-140797 A

  By the way, when high molding accuracy of the lens is required, a high work level is required for component adjustment, and linear alignment at a 1 μm level, for example, is required for each worker, which is very difficult. Therefore, countermeasure technology was required. Moreover, there are many mold components, and it is difficult to reproduce them at the 1 μm level after the mold is disassembled. Furthermore, there is a problem that it is difficult to improve the precision of the parts when the mold part processing requiring high precision is a square shape.

  This invention is made | formed in view of said situation, Comprising: It exists in providing the technique which improved the shaping | molding precision in the metal mold | die for lens shaping | molding.

  The present invention provides a lens molding die for molding a plastic lens, a first core for molding one side and a side surface of the plastic lens, a second core for molding the other side of the plastic lens, The first core includes a first insert and a second insert having a substantially cylindrical outer periphery, and the second insert is shrink-fitted into a cylindrical through-hole formed in the first insert. The tip of the second nest that protrudes from the through hole is a one-side lens molding part that molds one lens surface, and is a parting line with the second core of the first nest On one surface, either an inlay convex portion that protrudes toward the second core or a concave inlay recess on the first core side is formed, and the first core is formed on the second core. Said a And the other of fits writing spigot projection or spigot recess is formed by the low projection or spigot structure the spigot recess. By adopting such a structure, positioning by an inlay structure is possible, and stability of molding accuracy can be realized. In addition, the number of component parts can be reduced, and accumulated errors due to the accumulation of parts can be suppressed. In addition, when adopting shrink fitting, the shape of the second core insert is made substantially cylindrical, and the shape of the through hole is made cylindrical, so that cylindrical and cylindrical polishing can be achieved, and the accuracy of parts can be easily obtained. . In addition, since the alignment is not required by shrink fitting, it is possible to reduce mold correction during alignment. That is, the lead time can be shortened and the cost can be reduced.

  The spigot structure may include a gas vent groove. Due to the nested structure, there is no gap (or very narrow), and there is a risk that the escape space will be lost if gas is generated during resin molding. However, by providing a gas vent groove on either or both of the concave side and the convex side constituting the inlay structure, it is possible to suppress problems due to gas at the time of injection molding.

  The parting line may have a gas venting structure. Even in this structure, it is possible to suppress problems derived from gas during injection molding.

  The through hole of the first nesting includes a first nesting large diameter portion having a large diameter and a first nesting small diameter portion having a small diameter, and the second nesting is shrink-fit to the first nesting large diameter portion. A second nested large-diameter portion fixed by the first nested small-diameter portion and a second nested small-diameter portion fitted into the first nested small-diameter portion by a gap fit, and the tip of the second nested small-diameter portion is one-side lens molded Part. Since the second nested small-diameter portion is fitted to the first nested small-diameter portion by a clearance fit, the portion can be used as a gas vent. Accordingly, the gas hardly accumulates in the vicinity of the lens surface, and a reduction in molding accuracy due to defects derived from gas such as weld lines, peeling, and wrinkles can be suppressed.

  The first core is disposed on either the fixed side mold plate or the movable side mold plate, and the second core is disposed on the other side of the fixed side mold plate or the movable side mold plate. May have a wider gap fit. For example, the gap between the first core and the template is set to 3 μm or less, and the gap between the second core and the template is set to 10 μm or less.

  An alignment structure may be added to the second core. Even if the inlay structure (alignment-less structure) can no longer achieve accuracy due to repeated molding, the centering structure is added to the second core. The second core can be aligned, whereby a lens with high accuracy can be subsequently molded with the lens molding die. That is, the life of the mold can be extended.

  The first core may be a movable side.

  According to the present invention, in a lens molding die for molding a plastic lens, positioning by an inlay structure is possible, and stability of molding accuracy can be realized. Moreover, from another viewpoint, the number of component parts can be reduced, and an accumulated error due to the accumulation of parts can be suppressed. In addition, when adopting shrink fitting, the shape of the second core insert is made substantially cylindrical, and the shape of the through hole is made cylindrical, so that cylindrical and cylindrical polishing can be achieved, and the accuracy of parts can be easily obtained. . Further, from another viewpoint, alignment is not necessary due to shrink fitting, so that mold correction during alignment can be reduced. That is, the lead time can be reduced and the cost can be reduced.

It is a schematic diagram which shows the whole structure of the injection molding machine provided with the metal mold | die for lens shaping | molding based on embodiment. It is a top view which shows the parting surface of the stationary-side template based on embodiment. It is a top view which shows the parting surface of the movable side template which concerns on embodiment. It is an enlarged view of the fixed side core enclosed with broken line A1 of FIG. 2 based on embodiment. It is an enlarged view of the movable side core enclosed with broken line A2 of FIG. 3 based on embodiment. It is side surface sectional drawing which shows the joining state of the fixed side core and movable side core when the lens shaping die based on embodiment is closed.

  Hereinafter, modes for carrying out the invention (hereinafter referred to as “embodiments”) will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing an overall configuration of an injection molding machine 900 including a lens molding die 910 of the present embodiment. Using this lens molding die 910, a plastic lens is molded.

  The lens molding die 910 is mounted on the injection molding machine 900 with its fixed side mounting plate 912 attached to the stationary platen 921 of the injection molding machine 900 and the movable side mounting plate 914 attached to the movable board 922. The injection molding machine 900 opens and closes a movable side mold plate 915 that is a mold plate and a fixed side mold plate 913 that is a mold plate by a parting line PL to mold and take out a molded product (that is, a plastic lens). The type of the injection molding machine 900 is not limited as long as it is a molding machine capable of performing a general plastic injection molding operation.

  FIG. 2 is a plan view showing the parting surface 913a of the fixed side template 913. FIG. The parting surface 913a is formed with 12 fixed-side core accommodating portions 410 that are twelve nested accommodating portions at equal intervals in the circumferential direction with the center of the parting surface 913a as the center. A fixed-side core 100 having a substantially prismatic shape that is nested is fitted. For convenience of explanation, in FIG. 2, description of various pins and pin holes used for positioning, connection, guides, or the like of the members constituting the lens molding die 910 is omitted. Although details will be described later, the fixed-side core 100 uses a so-called gap fit for the nesting structure. The fixed side core 100 and the movable side core 200 described later adopt an inlay structure with concave and convex fitting, and have a centerless structure, thereby improving the accuracy during fitting. In addition, an alignment function (straight blocks 310 and 320 described later) is added to the fixed-side core 100, and the inlay structure is abolished so that alignment can be performed in case the accuracy is not obtained by use.

  In each fixed-side core accommodating portion 410, straight blocks 310 and 320, which are spacer members described later, are accommodated together with the fixed-side core 100. Each fixed-side core 100 is accommodated in the fixed-side core by the straight blocks 310 and 320. The arrangement position in the portion 410 is fixed by bolts 315 and 325 (see FIGS. 4 and 6). That is, the straight blocks 310 and 320 function as an alignment mechanism. From the center of the parting surface 100e of each fixed-side core 100, a tip portion of a lens molding portion 121 described later having a lens molding surface extends.

  On the parting surface 913a of the fixed-side template 913, a fixed-side runner half 960 that is a groove extending radially from the sprue runner 950 provided in the center in the plane direction is formed. It extends to the parting surface 100e.

  FIG. 3 is a plan view showing the parting surface 915 a of the movable side template 915. Similar to the parting surface 913a of the fixed side template 913, the parting surface 915a has 12 movable core cores 420 which are twelve nested housing parts at equal intervals in the circumferential direction around the center of the parting surface 915a. Each movable-side core housing 420 is fitted with a substantially cylindrical movable-side core 200 that is nested. The movable core 200 uses a so-called shrink fit in a nested structure. In FIG. 3, as in FIG. 2, the description of various pins and pin holes used for positioning, connection, guides, or the like of the members constituting the lens molding die 910 is omitted.

  A lens molding part 221 having a lens molding surface is exposed at the center of the parting surface 200e of each movable core 200.

  On the parting surface 915 a of the movable side template 915, a movable side runner half 970 that is a groove extending radially from the central sprue runner 950 in the plane direction is formed, and the parting surface of each movable side core 200 It extends to 200e.

  The fixed side core 100 and the movable side core 200 are arranged at positions facing each other, and when the lens molding die 910 is closed, a lens molding chamber 916 in FIG. 6 described later is formed. To do. Similarly, the fixed-side runner half 960 and the movable-side runner half 970 are also arranged at positions corresponding to each other, and the lens molding die 910 is closed, so that the sprue runner 950 enters the lens molding chamber 916. A runner that guides the molten resin is formed.

<Configuration of core>
FIG. 4 is an enlarged view of the fixed core 100 surrounded by a broken line A1 in FIG. FIG. 5 is an enlarged view of the movable core 200 surrounded by a broken line A2 in FIG. FIG. 6 is a side sectional view showing a joined state of the fixed side core 100 and the movable side core 200 when the lens molding die 910 is closed.

  First, an outline of the core configuration of the fixed core 100 and the movable core 200 will be described mainly with reference to FIGS. 4 and 5.

  The fixed core 100 has a multiple nesting structure (double nesting structure) in which a second nesting 120 is fitted in a first nesting 110. The movable core 200 also has a multiple nesting structure (double nesting structure) in which the second nesting 220 is fitted in the first nesting 210.

  As shown in FIG. 4, the fixed-side core 100 is a substantially quadrangular prism-shaped member whose corners in the circumferential direction of the outer peripheral surfaces (side surfaces 100 a, 100 b, 100 c, and 100 d) are chamfered. Further, the fixed-side core accommodating portion 410 that accommodates the fixed-side core 100 is formed in a concave shape on the parting surface 913 a of the fixed-side template 913. The inner peripheral surface of the fixed-side core housing portion 410 has side surfaces 410a, 410b, 410c, and 410d that are flat surfaces, and the fixed-side core extends along the outer peripheral surface (side surfaces 100a, 100b, 100c, and 100d) of the fixed-side core 100. A substantially quadrangular prism-shaped space into which 100 is fitted is formed.

  Of the side surfaces 410a, 410b, 410c, and 410d of the fixed-side core housing portion 410, the direction orthogonal to the depth direction (Z direction) of the side surfaces 410a and 410b is the width direction of the side surfaces 410a and 410b. In the center in the width direction of the side surfaces 410a and 410b, spacer arrangement portions 411 and 412 are formed, which are spaces in which the surface positions of the side surfaces 410a and 410b are recessed stepwise. The spacer arrangement portions 411 and 412 have a width that is about 1/3 of the total length in the width direction of the side surfaces 410a and 410b, and extend in the depth direction from the opening 410f of the fixed-side core housing portion 410. The spacer arrangement portions 411 and 412 are a minimum space in which the straight blocks 310 and 320 can be arranged.

  The fixed-side core 100 housed in the fixed-side core housing portion 410 is arranged in such a direction that the outer peripheral surface (side surfaces 100 a, 100 b, 100 c, 100 d) faces the inner peripheral surface of the fixed-side core housing portion 410. The surface position of the parting surface 100e of the fixed-side core 100 is aligned with the parting surface 913a of the fixed-side template 913.

  A straight block 310 is disposed on the side surface 100a side of the stationary side core 100 accommodated in the stationary side core housing portion 410 at a position in contact with the side surface 100a, and on the side surface 100b side, a straight block is disposed at a position in contact with the side surface 100b. 320 is arranged.

  A core-side contact surface 101 is formed from the opening 410f side of the fixed-side core housing portion 410 toward the bottom surface 410e side at the contact portion with the straight block 310 on the side surface 100a of the fixed-side core 100. The core-side contact surface 101 in the present embodiment is about 1/3 of the entire length of the side surface 100a in the width direction when the direction orthogonal to the height direction (Z direction) of the side surface 100a is the width direction of the side surface 100a. The width is assumed. The core-side contact surface 101 is formed to be depressed so that the surface of the side surface 100a is cut out.

  Similarly, the core-side contact surface 102 is provided also in the contact portion with the straight block 320 on the side surface 100b of the fixed-side core 100 from the opening 410f side to the bottom surface 410e side of the fixed-side core housing portion 410. . The core-side contact surface 102 also has a width of about 1/3 of the entire length in the width direction of the side surface 100b when the direction orthogonal to the height direction of the side surface 100b is the width direction of the side surface 100b. It is formed so as to be depressed so that the surface of 100b is cut out.

  On the surface of the parting surface 100e on the tip end side of the first nest 110, a spigot projection 190 is formed as a structure on one side of the spigot structure in a substantially annular shape except for the area of the fixed-side runner half 960 near the outer periphery. ing.

  As shown in FIG. 5, the movable-side core 200 employs a shrink-fitting nesting structure as described above, so that the outer periphery is a substantially cylindrical member, and the movable-side core 200 is formed in a cylindrical concave shape. The core housing 420 is fitted and disposed. The surface position of the parting surface 200e of the movable side core 200 is aligned with the parting surface 915a of the movable side template 915. Further, since the alignment-less structure is adopted, the alignment function is not provided.

  The movable core 200 includes, as a nested structure, an outer first nested 210 and an inner second nested 220 that fits into the first nested 210.

  In the outer periphery of the first nest 210 of the parting surface 200e, an inlay recess 290 that fits with an inlay protrusion 190 that is an inlay structure of the fixed core 100 is formed in a step shape that is one step lower than the parting surface 200e. Has been.

  In the step-shaped circumferential portion 290a of the inlay recess 290, six gas vent grooves 291 are formed at predetermined intervals in the circumferential direction. Further, on the outer edge of the first nest 210 (parting surface 200e) where the spigot recess 290 is formed, a slightly lower gas vent surface 292 (gas vent surface) is connected to the gas vent groove 291. Mechanism) is formed. With these structures, even when gas is generated during molding, it can be discharged to the outside, and adverse effects on lens molding can be eliminated.

  With reference to FIG. 6, the nesting structure of each of the fixed side core 100 and the movable side core 200 will be described. As described above, the fixed core 100 includes a multiple nesting structure (double nesting structure) in which the second nesting 120 is fitted into the first nesting 110 by a clearance fit, and these are fixed by the lock member 199. Has been. The movable core 200 also includes a multiple nesting structure (double nesting structure) in which the second nesting 220 is fitted in the first nesting 210 as described above, and is fixed by the lock member 299.

  As shown in the figure, the molding surface of the fixed side core 100 (first molding surface 117, second molding surface 127) and the lens molding surface of the movable side core 200 (first molding surface 217, second molding surface 227), A lens molding chamber 916 is formed. A plastic lens is molded in the lens molding chamber 916.

  The second molding surface 227 of the movable core 200 is a lens molding surface and forms a lens surface on one side of the plastic lens. The second molding surface 127 of the fixed core 100 is a lens molding surface and forms the other lens surface of the plastic lens. Here, one side and the other side of the lens surface are shown for convenience, and if the first convex lens surface 127 naturally corresponds to one side, the second molding surface 227 is on the other side. Will respond.

  The first molding surface 217 of the movable core 200 forms a flange surface that surrounds the outer periphery of the lens surface on one side of the plastic lens. Further, the side surface forming portion 218 of the movable side core 200 shapes the side surface of the plastic lens. The first molding surface 117 of the fixed core 100 forms a flange surface surrounding the outer periphery of the lens surface on the other side of the plastic lens. As shown here, it is preferable that the side surface forming part 218 for molding the side surface of the plastic lens is in the first core, that is, the movable side core 200 on the side subjected to shrink fitting. In general, for a plastic lens, the eccentricity measurement of the lens surface is performed with reference to the side surface. Therefore, since the side surface forming part 218 for molding the side surface is on the first core side (movable side core 200) subjected to shrink fitting, it is possible to further suppress the eccentricity of the lens surface on the other side of the lens, Highly accurate lens molding is possible.

  The fixed-side core 100 is configured by a combination of a first nest 110 and a second nest 120 fitted to the first body 110x of the first nest 110. The first body 110x of the first nest 110 has a recess 111 into which the second nest 120 is fitted.

  The recess 111 is a substantially cylindrical space formed by the opening 111a, the inner peripheral surface 111b, and the bottom surface 111c. The opening 111 a of the recess 111 is provided on the bottom surface 100 f of the fixed core 100. A circular through hole 112 is formed in the center of the bottom surface 111 c of the recess 111.

  Here, of the end surfaces of the second insert 120, the end surface on the bottom surface 111c side (+ Z direction side) of the recess 111 is defined as a front end surface 120a, and the end surface on the opposite side (−Z direction side) is defined as a rear end surface 120b. At this time, the front end surface 120 a of the second nest 120 is a plane that faces the lens forming portion 121 that is a substantially cylindrical protruding portion fitted in the through hole 112 of the recess 111 and the bottom surface 111 c of the recess 111. The flat part 122 is comprised.

  The lens molding part 121 extends vertically from the center of the flat part 122. A second molding surface 127 made of a convex surface is formed at the tip of the lens molding portion 121. The second molding surface 127 is mirror-finished by, for example, amorphal Ni—P plating.

  The second body 120x is formed with a screw hole 124 having an opening provided in the rear end surface 120b of the second insert 120. The screw hole 124 is a hole into which a tool provided with a male screw is screwed when the second insert 120 is pulled out from the recess 111.

  A metal annular spacer 138 is disposed between the bottom surface 111 c of the recess 111 of the first insert 110 and the flat portion 122 of the second insert 120. Further, in the recess 111 of the first insert 110, a metal annular spacer 151 that contacts the rear end surface 120b of the second insert 120 is fitted closer to the opening 111a of the recess 111 than to the second insert 120. Are combined. The lens thickness can be adjusted by appropriately processing or exchanging the annular spacers 138 and 151 with different thicknesses.

  Next, the movable core 200 will be described. The movable core 200 is configured by a combination of a first nest 210 and a second nest 220 fitted to the first body 210x of the first nest 210. The first body 210x of the second nest 210 has a recess 211 into which the second nest 220 is fitted.

  The recess 211 is a substantially cylindrical space formed by the opening 211a, the inner peripheral surface 211b, and the bottom surface 211c. The opening 211 a of the recess 211 is provided on the bottom surface 200 f of the fixed core 200. Further, a circular small-diameter through hole 212 having a smaller diameter than the first concave portion 211 is formed in the center of the bottom surface 211 c of the concave portion 211.

  Here, out of the end surfaces of the second insert 220, the end surface on the bottom surface 211c side (−Z direction side) of the recess 211 is defined as the front end surface 220a, and the end surface on the opposite side (+ Z direction side) is defined as the rear end surface 220b. At this time, the front end surface 220 a of the second nest 220 is a plane that faces the lens forming portion 221 that is a substantially cylindrical protruding portion fitted in the small-diameter through hole 212 of the recess 211 and the bottom surface 211 c of the recess 211. It is constituted by a certain plane portion 222.

  The lens molding part 221 extends vertically from the center of the flat part 222. A second molding surface 227 made of a convex surface is formed at the tip of the lens molding portion 221. The second molding surface 227 is mirror-finished by, for example, amorphal Ni—P plating.

  The second body 220x is formed with a screw hole 224 in which an opening is provided in the rear end surface 220b of the second insert 220. The screw hole 224 is a hole into which a tool provided with a male screw is screwed when the second insert 220 is pulled out from the recess 211.

  A metal annular spacer 238 is disposed between the bottom surface 211 c of the concave portion 211 of the first insert 210 and the flat portion 222 of the second insert 220. In addition, a metal annular spacer 251 that contacts the rear end surface 220b of the second insert 220 is fitted in the recess 211 of the first insert 210 closer to the opening 211a of the recess 211 than the second insert 220. Are combined. The lens thickness can be adjusted by appropriately processing or exchanging the annular spacers 238 and 251 with different thicknesses.

  Here, the through hole of the first nesting 210 includes a concave portion 211 that is a large-diameter first nesting large-diameter portion and a small-diameter through-hole 212 that is a small-diameter first nesting small-diameter portion. The second nest 220 is a second body 220x, which is a large-diameter second nest large-diameter portion fixed to the recess 211 by shrink fitting, and a small-diameter first nail 220 fitted into the small-diameter through hole 212 by a clearance fit. And a lens molding portion 221 that is a two-nested small-diameter portion. In this way, since the fitting is fixed by shrink fitting at a portion having a large diameter (that is, the concave portion 211 and the second body portion 220x), the clearance in the fitting state can be reduced. In addition, since the lens molding part 221 is a gap fit and has a certain clearance, the air in the lens molding chamber 916 that may directly affect the lens molding and the gas generated from the molten resin are good. Can be discharged. Therefore, it is difficult for gas or the like to accumulate in the lens molding chamber 916, particularly in the vicinity of the lens surface, and a reduction in molding accuracy due to defects derived from gas such as weld lines, peeling, and wrinkles can be suppressed.

  Further, the gap between the movable core 200 and the movable catch plate 915 is 3 μm or less. Further, the gap between the fixed side core 100 and the fixed side template 913 is 10 μm or less. Due to the shrink-fitting fixed structure and the inlay structure in the movable-side core 200, a gap between the fixed-side core 100 and the fixed-side template 913 that is not provided with the shrink-fitted structure is used as a path for releasing the gas generated during molding. Can be used.

The features of the present embodiment are summarized as follows.
In a lens molding die 910 for molding a plastic lens, a first core (movable side core 200) for molding one side surface and a side surface of the plastic lens and a second core for molding the other side surface of the plastic lens ( A fixed-side core 100). The first core (movable side core 200) includes a first nest 210 and a second nest 220 having a substantially cylindrical outer periphery. The second nest 220 is fixed to the cylindrical small-diameter through hole 212 formed in the first nest 210 by shrink fitting, and the tip of the second nest 220 protruding from the small-diameter through hole 212 has a lens on one side. A lens molding part 221 for molding the surface. On the surface that is a parting line with the second core 100 of the first nest 210, a concave portion protruding toward the second core (fixed side core 100) or concave on the first core (movable side core 200) side. Either one of the spigot recesses is formed, and the second core (fixed-side core 100) is a spigot projection or spigot that fits into the spigot protrusions or spigot recesses formed in the first insert 210 by a spigot structure. Either one of the recesses is formed. In the example of the above embodiment, the spigot structure is formed by fitting the spigot protrusion 190 of the fixed core 100 and the spigot recess 290 of the movable core 200. By adopting such a structure, positioning for each cabinet becomes possible, and stability of repeatability can be realized. In addition, the number of component parts can be reduced, and accumulated errors due to the accumulation of parts can be suppressed. Further, when adopting shrink fitting, by making the core shape round (substantially columnar), cylindrical polishing becomes possible, and the accuracy of parts can be easily obtained. In addition, since the alignment is unnecessary by shrink fitting, the number of mold corrections can be reduced. That is, the lead time can be shortened and the cost can be reduced.

  The spigot structure (the spigot protrusion 190 and the spigot recess 290) may include a gas vent groove 291. Although it is formed in the spigot concave portion 290 here, it may be formed in the spigot convex portion 190. Due to shrink fitting, there is no gap in the nested structure (or it becomes very narrow), and there is a risk that escape space will be lost if gas is generated during resin molding. However, by providing a gas vent groove (here, a gas vent groove 291 formed in the spigot recess 290) on either or both of the concave side and the convex side constituting the spigot structure, a problem due to gas at the time of injection molding Can be suppressed.

  The parting line may have a gas venting structure. Here, the degassing surface 292 is formed in the inlay recess 290. Even in this structure, it is possible to suppress problems derived from gas during injection molding.

  The through hole of the first nesting 210 includes a recess 211 that is a large-diameter first nesting large-diameter portion and a small-diameter through-hole 212 that is a small-diameter first nesting small-diameter portion. The second nest 220 includes a second body 220x fixed to the concave portion 211 by shrink fitting, and a lens forming portion 221 fitted to the small diameter through hole 212 by gap fitting. In this way, since the fitting is fixed by shrink fitting at a portion having a large diameter (that is, the concave portion 211 and the second body portion 220x), the clearance in the fitting state can be reduced. In addition, since the lens molding portion 221 is a gap fit and has a certain clearance, it is possible to satisfactorily discharge gas and air in the lens molding chamber 916 that has a high possibility of directly affecting lens molding. That is, therefore, gas or the like hardly accumulates in the vicinity of the lens surface, and a reduction in molding accuracy due to defects derived from gas such as weld lines, peeling, and wrinkles can be suppressed.

  The first core (movable-side core 200) is disposed on either the fixed-side template or the movable-side template, and the second core (fixed-side core 100) is either the fixed-side template or the movable-side template. Or the other. The second core (fixed side core 100) has a wider gap fit. Due to the shrink-fitting fixed structure and the inlay structure in the movable-side core 200, a gap between the fixed-side core 100 and the fixed-side template 913, which is not provided with the shrink-fitted structure, is used as a path for releasing the gas generated during molding. Can be used.

  An alignment structure may be added to the second core (fixed side core 100). Even if the inlay structure (alignment-less structure) can no longer be accurate due to repeated molding, the alignment structure is added to the fixed core 100, so the inlay structure is abolished. The second core can be aligned, whereby a lens with high accuracy can be subsequently molded with the lens molding die. That is, the life of the mold can be extended.

  Although the present invention has been described based on the embodiment, this embodiment is an exemplification, and various modifications can be made to combinations of the respective components, and such modifications are also included in the present invention. It will be understood by those skilled in the art that it is in the range.

100 Fixed side core 110, 210 First insert 112 Through hole 120, 220 Second insert 190 Inlay convex part 200 Movable core 211 Concave part 212 Small diameter through hole 218 Side surface forming part 220x Body part 221 Lens molding part 290 Inlay concave part 291 Degassing Groove 292 Degassing surface 900 Injection molding machine 910 Lens molding die 912 Fixed side mounting plate 913 Fixed side mold plate 914 Movable side mounting plate 915 Movable side mold plate 916 Lens molding chamber 921 Fixed platen 922 Movable platen

Claims (7)

In molds for molding plastic lenses,
A first core that molds one side and side surfaces of the plastic lens;
A second core for molding the other surface of the plastic lens,
The first core includes a first insert and a second insert having a substantially cylindrical outer periphery,
The second nest is fixed by shrink fitting into a cylindrical through hole formed in the first nest, and the tip of the second nest protruding from the through hole forms a lens surface on one side. One side lens molding part
On the surface that is a parting line with the second core of the first nesting, either an inlay convex portion that protrudes toward the second core or an inlay concave portion that is concave on the first core side is formed. ,
The second core is formed with either the spigot convex part or the spigot concave part that is fitted into the spigot convex part or the spigot concave part formed in the first nesting by a spigot structure by the spigot structure. Lens mold.   The lens mold according to claim 1, wherein the inlay structure includes a gas vent groove.   The lens molding die according to claim 1, wherein the parting line includes a gas venting mechanism. The through hole of the first nesting includes a first nesting large diameter portion having a large diameter, and a first nesting small diameter portion having a small diameter,
The second nesting includes a second nesting large diameter portion fixed to the first nesting large diameter portion by shrink fitting, and a second nesting small diameter portion fitted to the first nesting small diameter portion by a gap fit. With
The lens molding die according to any one of claims 1 to 3, wherein a tip of the second nesting small diameter portion is a one-side lens molding portion. The first core is disposed on either the fixed side mold plate or the movable side mold plate, and the second core is disposed on the other side of the fixed side mold plate or the movable side mold plate.
The lens mold according to any one of claims 1 to 4, wherein the second core has a wider clearance fit.   6. The lens molding die according to claim 1, wherein an alignment structure is added to the second core.   The lens molding die according to claim 1, wherein the first core is a movable side.

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