JP2008246847A - Mold for injection compression molding for light guide plate, and method for injection compression molding for light guide plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for injection compression molding for a light guide plate and a method for injection compression molding for the light guide plate capable of performing favorable transfer molding respectively different light guide plates by interchanging blocks. <P>SOLUTION: In the die 11 for injection compression molding for the light guide plate in which the distance of the cavity main face forming face 18a of a movable die 12 to a cavity main face forming face 42a of a fixed die 13 is changeably formed, a cavity main face forming block 18 for forming the cavity main face forming face 18a, and cavity side face forming blocks 29, 30 and 31 whose relative positions are changeably provided in at least mold opening/closing direction to the cavity main face forming block 18 are all changeably provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to an injection compression molding die for a light guide plate and an injection compression molding method for a light guide plate, and more particularly, to an injection compression molding die for a light guide plate for forming different light guide plates by exchanging blocks of the die. The present invention relates to an injection compression molding method for a mold and a light guide plate.

In the injection molding of a light guide plate, those described in Patent Documents 1 to 5 are known as methods for forming different light guide plates with the same mold. In each of Patent Documents 1 to 3, a different light guide plate is formed by exchanging a stamper on which a transfer pattern is formed or a similar metal plate, and the size of the light guide plate is changed. It was something that could not be handled. Further, Patent Document 4 is capable of forming flat molded products such as two or more kinds of light guide plates having different effective surface areas using the same mold by using a detachable flat plate insert. . Furthermore, in Patent Document 5, light guide plates having different specifications can be formed at low cost by exchanging a gate core of a mold used for forming the light guide plate. However, since Patent Document 4 and Patent Document 5 do not perform injection compression molding, there is a problem that good transfer cannot be performed. Further, the thickness of the light guide plate cannot be adjusted at all.

JP-A-9-131770 (Claim 1, 0007) Japanese Patent Laying-Open No. 2003-202424 (0010, FIG. 1) JP 2004-50685 A (0005, 0007) JP 2004-188612 (Claim 1, 0003, FIG. 2) JP 2002-210786 A (Claim 1, FIG. 3)

In view of the above problems, the present invention provides an injection compression molding die for a light guide plate and an injection compression molding method for a light guide plate that can satisfactorily transfer and mold different light guide plates by exchanging the mold blocks. The purpose is to provide.

An injection compression molding die for a light guide plate according to claim 1 of the present invention is an injection of a light guide plate in which a distance between a cavity main surface forming surface of a movable mold and a cavity main surface forming surface of a movable mold is variably formed. In the compression molding die, a cavity main surface forming block that forms a cavity main surface forming surface, and a cavity side surface forming block that is provided so that the relative position can be changed at least in the mold opening and closing direction with respect to the cavity main surface forming block, Both are provided so as to be replaceable.

An injection compression molding die for a light guide plate according to a second aspect of the present invention is the injection compression molding die for a light guide plate according to the first aspect, wherein the block forming at least one side of the cavity side surface forming block is urged by the pressing means against the cavity main surface forming block. It is characterized by being.

According to a third aspect of the present invention, there is provided the injection compression molding die for the light guide plate according to the first or second aspect, wherein the light incident surface forming block is replaceably disposed with respect to the cavity side surface forming block. It is characterized by

An injection compression molding die for a light guide plate according to a fourth aspect of the present invention is the injection compression molding die for a light guide plate according to the first aspect, wherein one of the cavity side surface forming block and the cavity main surface forming block is disposed in the stationary die. Is arranged in a movable mold.

According to a fifth aspect of the present invention, there is provided an injection compression molding method for a light guide plate, wherein the distance between the cavity main surface forming surface of the movable mold and the cavity main surface forming surface of the movable mold is variably formed. Using a molding die, replace the cavity main surface forming block that forms the cavity main surface forming surface and the cavity side surface forming block that can be changed relative to the cavity main surface forming block at least in the mold opening and closing direction. Then, different light guide plates are formed by the same mold.

According to a sixth aspect of the present invention, there is provided the injection compression molding method for a light guide plate according to the fifth aspect, wherein the cavity side surface forming block and the cavity main surface forming block are both disposed in either the fixed mold or the movable mold. The removal order of the blocks is characterized in that the cavity main surface forming block is removed after the cavity side surface forming block is removed.

According to a seventh aspect of the present invention, there is provided an injection compression molding method for a light guide plate according to the fifth or sixth aspect, wherein the cavity main surface forming block is changed to a cavity main surface forming block having a different plate thickness. The light guide plates having different thicknesses are formed.

An injection compression molding die for a light guide plate and an injection compression molding method for a light guide plate according to the present invention include a cavity main surface forming block for forming a cavity main surface forming surface, and at least a mold opening / closing direction with respect to the cavity main surface forming block. Since all of the cavity side surface forming blocks provided so that the relative position can be changed are provided so as to be exchangeable, different light guide plates can be transferred and molded with the same mold.

An injection compression molding die and injection compression molding method for a light guide plate of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of an injection compression molding die of a light guide plate according to the present embodiment, and shows a state when the die is brought into contact. FIG. 2 is a cross-sectional view of the injection compression molding die of the light guide plate of the present embodiment, showing a state when the mold is clamped and the cavity volume is reduced. FIG. 3 is a front view of the movable mold of the injection compression molding mold of the light guide plate of the present embodiment. FIG. 4 is a cross-sectional view of the injection compression molding die of the light guide plate of the present embodiment, showing a state in which the blocks are exchanged to form different light guide plates. FIG. 5 is a front view of the movable mold in FIG. FIG. 6 is a chart showing the injection compression molding method for the light guide plate of the present embodiment.

An injection compression molding die 11 for a light guide plate according to this embodiment is a die for molding a mobile phone sidelight type light guide plate having a diagonal size of 3 inches and a plate thickness of 0.4 mm by injection compression molding. (Hereinafter, the side light type light guide plate for mobile phones is simply abbreviated as a light guide plate.) Injection compression molding is performed between the start of molding and the end of molding, and the cavity main surface forming surface 18a of the movable mold 12 and the fixed mold. The space | interval of the cavity main surface formation surface 42a of the type | mold 13 becomes variable. Accordingly, the injection compression molding includes a type called an injection press in which the movable mold is advanced as it is after the molten resin is injected at the stop position when the mold is closed. In these injection compression moldings, since the cavity is slightly opened before the start of injection or after the start of injection, there is no need for an injection device having a high speed injection capability, and the molten resin can be injected at a relatively low speed and low pressure. Since the movable mold 12 is moved in the mold clamping direction after the start of injection to compress the molten resin, the flow of the molten resin is accelerated at a position far from the gate P3 of the cavity C, or fine transfer is favorably performed. There is an advantage that you can. Furthermore, after the gate P3 is cut, the normal injection mold cannot apply pressure from the injection device. However, in the case of the injection compression mold, the molten resin in the cavity C is compressed. It is possible to cope with shrinkage caused by cooling and solidification. Such injection compression molding is particularly advantageous when a light guide plate having a thin plate thickness compared to the area such as the light exit surface is formed.

1 and 2 are cross sections of an injection compression molding die 11 of the present embodiment. 1 and 2 and FIGS. 4, 7, 8, 10, and 11, which will be described later, the relationship between members such as blocks, bolts, and springs and the cooling medium flow path is easy to understand. These are schematically shown on the same cross section. However, in the actual injection compression mold 11, they are not located in the same cross section, as is apparent from the front views of FIGS. 3, 5, and 9. The injection compression molding die 11 includes a movable die 12 as a first die and a fixed die 13 as a second die. A cavity C having a variable thickness is formed. A movable mold 12 attached to a movable platen of an injection compression molding machine (not shown) includes a mold body 15 having a heat insulating plate 14 attached to the movable platen side, a core base block 17, a cavity main surface forming block 18, a runner. A core portion 16 formed from the forming block 19 and the like, and a movable frame portion 22 formed from the frame base portion 20, the cavity side surface forming blocks 29, 30, 31 and the like are provided.

A core base block 17 is detachably disposed by a bolt (hexagon socket head cap bolt) 21 at a substantially central portion of the surface of the mold main body 15 on the fixed mold 13 side. A concrete fixing method is that a concave portion capable of accommodating the head of the bolt 21 is formed on the movable plate side of the mold main body portion 15 and a through hole is formed at the center of the concave portion toward the core base block 17 side. ing. Further, screw holes for bolts are also formed on the mold main body 15 side of the core base block 17. The core base block 17 is fixed by inserting and screwing the bolt 21 from the movable platen side of the mold main body 15 through the through hole toward the bolt screw hole of the core base block 17. In addition, a cavity main surface forming block 18 is detachably disposed by bolts 23 on the fixed mold 13 side of the core base block 17. The fixing method of the cavity main surface forming block 18 is the same as that of the core base block 17, and the bolt is directed from the mold main body 15 side of the core base block 17 to the bolt screw hole of the cavity main surface forming block 18 through the through hole. The cavity main surface forming block 18 is fixed by inserting and screwing 23. The core part may be formed entirely from the cavity main surface forming block.

The cavity main surface forming block 18 has a cavity main surface forming surface 18a that forms a light output surface, which is one main surface of the light guide plate, and a protrusion in the vicinity thereof, on the surface facing the fixed mold 13 of the cavity main surface forming block 18. It has a substantially quadrangular shape that substantially matches the shape of the light guide plate including the protrusions. In this embodiment, the cavity main surface forming surface 18a is a mirror surface. However, in the case where a light emitting surface is provided on the movable mold side, a groove or roughened surface may be used. Also, in the case where a stamper or the like is further arranged on the cavity main surface forming block and the transfer is performed to the light guide plate through the stamper, the area or shape of the main surface of the light guide plate is determined by the cavity main surface forming block. It is included in the scope of the invention. Further, the portion formed by the cavity main surface forming surface may not be a light exit surface or a light entrance surface, but may include a runner, a gate, etc. in part.

A cooling medium flow path 24a is disposed in the cavity main surface forming block 18 in parallel with the cavity main surface forming surface 18a so that the molten resin in the cavity C is cooled. The cooling medium flow path 24 a in the cavity main surface forming block 18 is connected to the cooling medium flow path 24 b of the core base block 17, and the cooling medium flow path 24 b is connected to the cooling medium flow path in the mold main body 15. It communicates with the temperature controller outside the mold through 24c. O-rings 24d are inserted around the cavity main surface forming block 18, the core base block 17, and the connection portions of the cooling medium flow paths 24a, 24b, and 24c of the mold main body 15, respectively. The cooling medium does not leak from between the blocks 17 and 18. In addition, the cavity main surface forming block may be thinned, and the cooling medium flow path may be formed between the cavity main surface forming block and the core base block in parallel with the cavity main surface forming surface.

A runner forming block 19 is fixed to the lower side of the core portion 16 by a bolt (not shown), which is substantially in the center of the surface of the mold main body 15 on the fixed mold 13 side. The runner forming block 19 is provided with an ejector pin 25 that penetrates the mold main body 15 and is movable forward and backward. The leading end faces the runner forming surface 19a, and a biting portion is provided in a Z-shaped cross section so that the sprue P1 and the runner P2 can be easily held.

A cooling medium flow path 26 a is formed in the runner forming block 19 so as to surround the protruding pin 25. The cooling medium flow path 26a is formed to cool the runner forming surface 19a, the gate cutter 27, the protruding pin 25 and the like, passes through the runner forming block 19, and is connected to the cooling medium flow path 26b of the mold main body 15. And communicated with a temperature controller outside the mold.

Further, a gate cutter 27 of the gate cutter device is disposed between the runner forming block 19 and the cavity main surface forming block 18 so as to be able to move forward and backward. In both the ejector device and the gate cutter device, a plate and a spring for retracting the pins and the cutter are provided in the mold body 15.

Concave portions are formed at four locations near the upper and lower four corners on the surface of the mold main body portion 15 on the fixed mold 13 side, and springs 28 are attached to the fixed mold 13 side in the concave portions. Yes. The fixed mold 13 side of the spring 28 is fixed to the frame base portion 20 of the movable frame portion 22 disposed so as to surround the core portion 16. The frame base 20 is formed so as to surround the core base block 17 with a certain gap H therebetween. The thickness of the frame base 20 is substantially the same as that of the core base block 17. Further, a guide rod (not shown) is provided on the mold body 15 toward the fixed mold 13, and the guide rod is inserted into the hole of the frame base 20, thereby moving the frame base 20 in the mold opening / closing direction. I am guiding.

As shown in FIG. 3, cavity side surface forming blocks 29, 30, and 31 are detachably disposed on the side of the fixed mold 13 of the frame base 20 by bolts 32, 33, and 34. The cavity side surface forming blocks 29, 30, and 31 have a frame shape that surrounds the cavity main surface forming block 18 together. However, the side surface forming block may have a frame shape that is not divided, or may be divided into other numbers. The inner side surfaces of the cavity side surface forming blocks 29, 30, and 31 are substantially in contact with the outer side surface of the cavity main surface forming block 18 so that the relative position can be changed at least in the mold opening / closing direction. The cavity side surface forming blocks 29 a, 30 a, and 31 a have a cavity side surface forming surface 29 a, 30 a, and 31 a on the front side (the portion near the fixed mold 13). The contact surfaces 29b, 30b and 31b are formed.

As shown in FIG. 3, the cavity side surface forming block 29 is adjacent to the lower and left sides of the cavity main surface forming block 18 and the runner forming block 19, and is moved only in the mold opening / closing direction. A recess that can accommodate the head of the bolt 32 is formed on the contact surface 29 b of the cavity side surface forming block 29, and a through hole is formed toward the frame base 20. And the screw hole for bolts is formed in the same position in the surface orthogonal to the type | mold opening / closing direction of the frame base part 20. As shown in FIG. The cavity side surface forming block 29 has a positioning pin (not shown) with respect to the frame base portion 20. Accordingly, in the cavity side surface forming block 29, the positioning pin is inserted into a hole (not shown) of the frame base 20, and the bolt 32 is inserted into the through hole and screwed into the bolt screw hole of the frame base 20. It is fixed detachably.

As shown in FIG. 3, the cavity side surface forming block 30 is positioned above the cavity main surface forming block 18 and is detachably fixed to the frame base portion 20 by bolts 33. In this embodiment, a concave portion is provided on the fixed mold 13 side of the contact surface 30b of the cavity side surface forming block 30, and another through hole is provided in the mold opening / closing direction toward the concave portion. Then, by inserting a bolt 36 from the frame base 20 side of the through hole and screwing it into a bolt screw hole formed in the light incident surface forming block 35, the light incident surface forming block 35 can be replaced in the recess. It is fixed to. Therefore, in the present embodiment, by replacing only the light incident surface forming block 35, the light incident surface that greatly affects the optical characteristics due to a subtle difference in shape can be formed into an optimal shape. The light incident surface may be formed by the cavity side surface forming block 30.

Further, a bracket 37 is projected and fixed above the frame base portion 20 so as to extend toward the fixed mold 13 side. As for the fixing method of the bracket 37, a through hole is formed in the bracket 37, and the bolt 37 is fixed by inserting and screwing into the bolt screw hole formed in the frame base portion 20 through the through hole. A concave portion is formed on the inner side surface of the bracket 37, and a spring 38 as a pressing means is fixed to the concave portion. The tip of the spring 38 is in contact with the outer wall surface of the cavity side surface forming block 30. Accordingly, the cavity side surface forming block 30 is urged and pressed toward the center of the cavity main surface forming block 18. The cavity side surface forming block 30 is fixed to the frame base portion 20 by the bolts 33, and is pressed further toward the center for the following reason. That is, a slight gap exists between the through hole of the cavity side surface forming block 30 and the bolt 33. Therefore, the arrangement position of the cavity side surface forming block 30 generated by the gap in the direction orthogonal to the mold opening / closing direction is set as a desirable arrangement position.

As shown in FIG. 3, the cavity side surface forming block 31 is located on the right side of the cavity main surface forming block 18, and is detachably fixed to the frame base portion 20 with bolts 34. The method of fixing and attaching / detaching the cavity side surface forming block 31 to the frame base 20 with the bolts 34 is the same as in the case of the cavity side surface forming blocks 29 and 30 described above. The cavity side surface forming block 31 is also constantly pressed toward the center of the cavity main surface forming block 18 for the same reason and configuration as the cavity side surface forming block 30. That is, the bracket 39 is fixed to the side surface of the frame base portion 20 by a bolt (not shown). The bracket 39 extends to the fixed mold 13 side, and the tip of the spring 40 of the pressing means fixed to the recess inside the bracket 39 is in contact with the outer wall surface of the cavity side surface forming block 31.

Further, an air passage 62 or the like is formed between the cavity side surface forming blocks 29, 30, and 31, which are the movable frame portion 22, and the cavity main surface forming block 18 and the runner forming block 19, and air is ejected from the air passage 62 and the like. By doing so, it assists at the time of releasing the light guide plate or the runner. In addition, air can be ejected from these air passages 62 and the like even if the cavity main surface forming block 18 and the cavity side surface forming blocks 29, 30, and 31 are replaced, like the cooling medium flow paths 24a and 24b. . The cavity main surface forming block 18 is pressed by pressing the cavity side surface forming blocks 30 and 31 having at least one side, more preferably two or more sides, in the direction perpendicular to the mold opening / closing direction toward the cavity main surface forming block 18. When the cavity side surface forming blocks 29, 30, and 31 are thermally expanded, the positional relationship is not hindered.

Next, the fixed mold 13 will be described. As shown in FIGS. 1 to 3, the fixed mold 13 attached to a fixed plate of an injection compression molding machine (not shown) includes a mold main body 41 and a cavity main surface. A block 42, an insert block 43, a sprue bush 44, a fixed gate cutter 45, and a contact block 46 are provided. A heat insulating plate 47 is attached to the fixed plate side of the mold main body 41, and a hole 48 into which a nozzle of an injection device (not shown) is inserted is formed. A locating ring 49 is attached around the hole 48. A cavity main surface forming block 42 is detachably attached to the movable mold 12 side of the mold main body 41 by a bolt 50, and a surface of the cavity main surface forming block 42 facing the movable mold 12 is a cavity main surface. It becomes the formation surface 42a. In the present embodiment, the main surface forming surface 42a is a portion that forms the reflecting surface of the light guide plate, and fine dots are engraved therein. A stamper may be provided on the surface of the cavity forming surface. Further, a cooling medium flow path 51a is formed in the cavity main surface forming block 42 in parallel with the cavity main surface forming surface 42a, and the cooling medium flow path 51a is a cooling medium flow in the mold main body 41. It is connected to a temperature controller outside the mold via a path 51b. An O-ring 51c is inserted around the connecting portion of the cooling medium flow paths 51a and 51b between the cavity main surface forming block 42 and the mold main body 41, so that the cooling medium does not leak between the two. Yes.

An insert block 43 is fixed to the mold main body 41 below the cavity main surface forming block 42. The sprue bush 44 is fixed inside the insert block 43, and the tip end surface of the sprue bush 44 and the runner forming surface 43 a on the movable mold 12 side of the insert block 43 are connected to the runner of the runner forming block 19 of the movable mold 12. It faces the formation surface 19a. The runner formation surface 43a is a surface that forms the runner P2 together with the runner formation surface 19a and the like. The width of the runner formation surface 43a in the direction perpendicular to the flow direction of the molten resin gradually increases from the portion adjacent to the sprue bush 44 toward the cavity C. A cooling medium flow path 52 a is formed in the insert block 43 so as to surround the sprue bush 44. The cooling medium flow path 52a is formed to cool the sprue bush 44, the runner forming surface 43a, and the fixed gate cutter 45, passes through the insert block 43, and passes through the cooling medium flow path 52b in the mold main body 41. The mold body 41 communicates with a temperature controller outside the mold.

A fixed gate cutter 45 is fixed between the insert block 43 and the cavity main surface forming block 42. The width of the fixed gate cutter 45 in the direction perpendicular to the flow direction of the molten resin is the same as or slightly wider than that of the gate cutter 45. Air passages 53 are also formed between the cavity main surface forming block 42 and the contact block 46 of the fixed mold 13. The contact block 46 is formed around the cavity main surface forming block 42 and the insert block 43, and is formed in a frame shape in this embodiment. However, the insert block 43 may be divided into a plurality of parts. The movable block 12 side of the contact block 46 is a contact surface 46a that contacts the contact surfaces 29b, 30b, 31b of the cavity side surface forming blocks 29, 30, 31. The contact block 46 is formed with a through hole having an enlarged diameter on the contact surface 46a side in the mold opening / closing direction. The abutment block 46 is fixed by inserting and screwing bolts 55 from the abutment surface 46 a side toward the bolt screw holes of the mold main body 41.

Next, referring to FIGS. 4 and 5, a description will be given of an injection compression molding method of a light guide plate in which a part of the same injection compression molding die 11 is replaced to form a different light guide plate. The reason why a different light guide plate is formed by exchanging a part of the blocks of the injection compression mold 11 is to increase the cost if a dedicated injection compression mold is prepared each time a different light guide plate is formed. Because it is connected. In particular, in the case of a light guide plate for a mobile phone, the screen has become larger in recent years. However, it is possible to cope with an increase in the size of the light guide plate by simply exchanging a part of the mold, leading to cost reduction. In the case of a light guide plate, strict standard optical property values may not be realized with a die that is processed only by the calculated values at the initial mold design, so that only a part of the die can be replaced later. It is desirable to keep it.

As a first example, a case will be described in which only the light incident surface forming block 35 is replaced due to a change in the shape of the light incident surface of the light guide plate or wear of the light incident surface 35a of the mold. First, the injection compression molding die 11 shown in FIGS. 1 to 3 is removed from a fixed plate and a movable plate (not shown) and taken out of the injection compression molding machine. Next, the bolt 61 is removed, and the bracket 37 is removed. Next, the bolt 33 is removed, and the cavity side surface forming block 30 is removed from the frame base portion 20. Then, the bolt 36 is removed from the cavity side surface forming block 30, the light incident surface forming block 35 is removed, and a different light incident surface forming block is replaced. At the time of assembly, the cavity side surface forming block 30 and the like are assembled in a state where they can be molded by the reverse procedure described above.

As a next example, the case where the shape of the main surface (light-emitting surface and reflecting surface) of the light guide plate is changed will be described. First, the injection compression molding die 11 of the light guide plate is removed from the injection compression molding machine. For the movable mold 12, the bolts 61 and the like are removed, and the brackets 37 and 39 are removed. Next, the bolts 32, 33, 34 are removed, and the cavity side surface forming blocks 29, 30, 31 are removed from the frame base 20. Next, the bolt 21 locked from the back side of the mold main body 15 is removed, and the entire core 16 is removed from the mold main body 15. Then, the bolt 23 is removed from the surface of the core base block 17 on the mold main body 15 side, and the core base block 17 and the cavity main surface forming block 18 are separated. Next, when the new cavity main surface forming block 18 is mounted and assembled, the new cavity main surface forming block 18 is fixed to the core base block 17 again by the bolt 23. At this time, needless to say, the cavity main surface forming block 18 to be newly attached is also formed with bolt screw holes into which the bolts 23 can be screwed at the same position in the surface direction orthogonal to the mold opening / closing direction. The positions of the cooling medium flow path 24a of the cavity main surface forming block 18 and the cooling medium flow path 24b of the core base block 17 are also the same position. Then, the core base block 17 fixed to the cavity main surface forming block 18 is fixed to the mold body 15 with the bolt 21. When forming light guide plates having different thicknesses, or when finely adjusting the thickness of light guide plates having the same specifications, only the cavity main surface forming block 18 has a different thickness. It may be changed to 18.

Next, the cavity side surface forming blocks 29, 30, and 31 are fixed. In the example of FIGS. 4 and 5, the cavity main surface forming block 18 for the light guide plate having a large area is replaced, and the cavity side surface forming blocks 29, 30, and 31 are also replaced with correspondingly disposed outside. The In the movable mold 12, a gap H is formed in advance between the core base block 17 and the frame base 20, and the mounting position of the spring 28 is relatively closer to the outer wall surface. Therefore, as in the example of FIGS. 4 and 5, the area of the surface of the core base block 17 that comes into contact with the cavity main surface forming block 18 is different from the core base block 17 of the cavity main surface forming block 18 to be newly attached. Even when the area of the abutting surface is larger, the core base block 17 and the cavity main surface forming block 18 can move relative to each other in the mold opening / closing direction without interfering with each other. .

The procedure for fixing the cavity side surface forming blocks 29, 30, and 31 is as follows. First, the cavity side surface forming block 29 is positioned and fixed to the frame base portion 20 with bolts 32 and pins (not shown). Next, the cavity side surface forming blocks 30 and 31 are attached to the frame base portion 20 with bolts 33 and 34. At this time, the tightening torque of the bolts 33 and 34 is slightly weakened. Next, the brackets 37 and 39 are fixed to the frame base portion 20 with bolts 61 and the like, and the cavity side surface forming blocks 30 and 31 are pressed toward the cavity main surface forming block 18 with the springs 38 and 40. Finally, tightening of the cavity side surface forming blocks 30 and 31 with the bolts 33 and 34 is strengthened to completely fix the cavity side surface forming blocks 30 and 31 and the frame base 20. In addition, about the division | segmentation number of a cavity side surface formation block, it may be changed by replacement | exchange.

On the other hand, the block of the fixed mold 13 is also exchanged according to the change of the block of the movable mold 12.
That is, the bolt 55 for fixing the contact block 46 is removed, and the contact block 46 is removed from the mold body 41. Further, from the mold body 41 side, the bolt 50 for fixing the cavity main surface forming block 42 is removed, and the cavity main surface forming block 42 is removed. The cavity main surface forming block 42 is changed to a shape and area corresponding to the cavity main surface forming block 18 of the movable mold 12 according to the shape of the light guide plate. Further, the contact block 46 surrounding the cavity main surface forming block 42 is also replaced in accordance with the shape and area of the cavity main surface forming block 42. The abutting surface 46a of the abutting block 46 is replaced with one having a shape and an area substantially matching the abutting surfaces 29b, 30b, 31b of the cavity side surface forming blocks 29, 30, 31.

Next, the molding process by the injection compression molding die 11 of the present embodiment will be described with reference to the chart of FIG. In this embodiment, a light guide plate having a diagonal size of 3 inches and a plate thickness of 0.4 mm is formed in a molding cycle time of 4 seconds. The breakdown is as follows: mold opening / closing time (including removal time and intermediate time) 1.35 seconds, injection time 0.05 seconds, pressure holding time 0.4 seconds, cooling time 2.2 seconds (substantially cooling from the start of injection) It has started). For this reason, in the present embodiment, the cooling medium flow path 24a for cooling the cavity main surface forming surface 18a of the movable mold 12, such as the cooling medium flow path 26a for cooling the vicinity of the protruding pin 25 and the runner forming surface 19a, and the fixed mold 13 are used. Glass transition of polycarbonate, which is a resin molded by a temperature controller, to the cooling medium flow path 51a for cooling the cavity main surface forming surface 43a, the vicinity of the sprue bushing 44, and the cooling medium flow path 52a for cooling the vicinity of the runner forming surface 43. A cooling medium (cooling water) whose temperature is controlled to about 80 to 120 ° C., which is 40 to 70 ° C. lower than the temperature Tg, is flowing.

Further, the temperature of the front zone (zone closest to the nozzle) of the injection apparatus is set to 310 ° C., and the molten resin of polycarbonate is measured. In addition, as for the temperature setting of the front zone of the said injection apparatus at the time of using a polycarbonate, it is desirable to set temperature to 300-350 degreeC. Then, a mold clamping device (not shown) is operated, and the mold is closed by bringing the movable mold 12 attached to the movable plate into contact with the fixed mold 13 attached to the fixed platen. The relationship between the core portion 16 and the movable frame portion 22 of the movable mold 12 when the mold is closed is the state shown in FIG. Next, the mold clamping force is increased to 50 to 200 kN to perform mold clamping. As a result, as shown in FIG. 2, the resilient force of the spring 28 is overcome and the mold body 15 of the movable mold 12 and the frame base 20 of the movable frame 22 are brought into contact with or close to each other. The cavity side surface forming blocks 29, 30, and 31 of the movable frame portion 22 are retracted from the cavity main surface forming block 18. A runner P2 including a variable thickness gate P3 and a variable thickness cavity C connected to the runner P2 are formed between the fixed mold 13 and the movable mold 12. At this time, it is desirable to suck the air in the cavity C from the viewpoint of the molten resin flow in the cavity C.

Next, when a predetermined delay time elapses, the molten resin is injected from a nozzle of an injection device (not shown) through the sprue bush 44 at an injection speed of 100 to 200 mm / sec. The mold main body portion 15 and the core portion 16 of the movable platen and the movable die 12 are in a state in which the core portion 16 is retracted again as shown in FIG. 1 due to the pressure at the time of injection. As a result, the movable frame portion 22 of the movable mold 12 is positioned relatively forward of the core portion 16, and the cavity main surface forming surface 42 a of the fixed mold 13 and the cavity main surface forming surface 18 a of the movable mold 12. As compared with the position where the mold clamping force is first exerted as shown in FIG. Similarly, when the distance between the fixed mold 13 and the movable mold 12 is increased, the distance between the runner P2 and the gate P3 is opened by 50 to 200 μm, and the molten resin is applied to the cavity C in which the sectional area of the gate P3 is increased. Injection can be performed, and the flow loss of the molten resin can be reduced. As a result, since the molten resin can be injected at a relatively low speed and low pressure, there is an advantage that internal stress is not generated particularly near the gate of the light guide plate.

When the screw position reaches a predetermined holding pressure switching position by the injection device, the injection control is switched to the holding pressure control. Even after switching to holding pressure control, mold clamping is performed with a high clamping force on the mold clamping device side, so the mold opening direction during the above injection or a distance less than that distance is the mold clamping direction. The core part 16 (cavity main surface forming surface 18a) of the movable mold 12 is moved to. Alternatively, when the position of the movable mold 12 at the start of injection is more open than the fully clamped position, the mold clamping amount (position) may be advanced more than the mold opening amount (position). . Then, the mold clamping force is decreased after a predetermined time from switching to the holding pressure control or simultaneously with the holding pressure switching. In this embodiment, the gate P3 is cut by a gate cutter device (not shown) at the same time when the mold clamping force is reduced. In this embodiment, the gate cutter is not changed even when the size of the light guide plate is changed. However, when changing to molding of a large light guide plate, the gate portion is widened and the width of the gate cutter (perpendicular to the flow direction of the molten resin). The length) may also be increased.

As described above, in the present embodiment, after the gate P3 is cut by the gate cutter 27, the holding pressure from the injection device side does not completely reach the molten resin in the cavity C. When the movable mold 12 is advanced by driving, the cavity main surface forming block 18 moves forward relative to the cavity side surface forming blocks 29, 30, 31, and the molten resin in the cavity C can be compressed. . Since the cooling medium flows through the cooling medium flow paths 24a, 26a, 51a, and 52a, cooling and solidification of the molten resin in the cavity C, the runner P2, and the sprue P1 proceed. The mold release air is applied to the air passages 53, 62, etc. before the mold is opened, and the cavity main surface forming surfaces 18a, 42a, the cavity side surface forming surfaces 29a, 30a, 31a of the light guide plate, and the runner are removed together with the pressure relief and mold opening. Release from the formation surfaces 19a, 43a, etc. is promoted. When the mold is opened, removal is performed by an unillustrated removal robot.

Next, an injection compression molding die 65 for the light guide plate in another embodiment shown in FIGS. 7 to 9 will be described. FIG. 7 is a sectional view of an injection compression molding die for a light guide plate according to another embodiment, and FIG. 8 is a sectional view of an injection compression molding die for a light guide plate according to another embodiment. It is a figure which shows a state when the volume reduces. FIG. 9 is a front view of the movable mold of the injection compression molding mold of the light guide plate of another embodiment. Another embodiment shown in FIGS. 7 to 9 is a change accompanying an increase in the number of cavities in the mold to 2, and the technical idea itself is substantially the same as the embodiment of FIGS. . The number of cavities is not limited as long as it is plural. Accordingly, the same parts as those in FIG. 1 and the like are denoted by the same reference numerals, description thereof will be omitted, and differences will be mainly described.

An injection compression molding die 65 according to another embodiment includes a movable die 66 as a first die and a fixed die 67 as a second die, and the die-matched both dies 66 and 67 are combined. Cavities C1 and C2 with variable volume and thickness are formed between the two. The movable mold 66 is provided with a mold main body portion 15, a core portion 16, a movable frame portion 22 and the like, and the position of the core portion 16 and the movable frame portion 22 can be relatively changed in the mold opening / closing direction. The core portion 16 includes two cavity main surface forming blocks 18 and 18 and a runner forming block 19. Further, an ejector pin 25 of the ejector device is disposed at a position facing the sprue bush 44 of the runner forming block 19.

And the attachment method of the core base block 17 and the cavity main surface formation block 18 with respect to the metal mold | die main-body part 15 is also performed with the volt | bolts 21 and 23 similarly. The movable frame portion 22 surrounding the core portion 16 is also composed of a frame base portion 20 and cavity side surface forming blocks 29, 30 and 31. The difference from the previous embodiment shown in FIGS. 1 to 6 is that the cavity side surface forming blocks 29, 30, 31 are arranged symmetrically about the protruding pin 25 and are fixed to the brackets 39, 39. The cavity side surface forming blocks 31, 31 pressed by 40, 40 are provided on different sides of the upper cavity C1 and the lower cavity C2. The cavity side surface forming block 29 constituting one side surface forming surface 29a1 and the gate side side surface forming surface 29a2 in the upper cavity C1 is brought into contact with the cavity side surface forming block 31 constituting the lower cavity C2, and the lower side. The side surface forming surface 29a3 on the gate side in the cavity C2 is also configured. Similarly, the cavity side surface forming block 29 constituting one side surface forming surface 29a4 of the lower cavity C2 and the side surface forming surface 29a5 on the gate side is brought into contact with the cavity side surface forming block 31 constituting the upper cavity C1. Further, a side surface forming surface 29a6 on the gate side of the upper cavity C1 is also configured.

A light incident surface forming block 35 is detachably fixed to the cavity side surface forming block 30 disposed above the upper cavity C1 and below the lower cavity C2, respectively, and a spring 38 disposed on the bracket 37. Is also pressed in the center direction of the cavities C1 and C2, respectively, in the same manner as the embodiment of FIGS. In addition, a gap H is provided between the core base block 17 and the frame base 20, and the cavity main surface forming block 18 having a size indicated by a broken line in FIG. 9 can be replaced as shown in FIGS. This is the same as the embodiment. Further, even if the cavity main surface forming block 18 and the like are replaced, the cooling medium flow path 24a and the air passage 62 and the air passage 62 are communicated as they are and operate without any trouble.

On the other hand, as shown in FIGS. 7 and 8, the mold body 41, the cavity main surface forming blocks 42 and 42, and the insert block 43 are also provided for the fixed mold 67 attached to the fixed plate of the injection compression molding machine (not shown). , A sprue bush 44, a fixed gate cutter 45, a contact block 46, and the like. The cavity main surface forming blocks 42 and 42 are formed with cavity main surface forming surfaces 42a and 42a so as to face the cavity main surface forming surfaces 18a and 18a of the movable mold 66, respectively. A contact block 46 is formed so as to surround the cavity main surface forming block 42 and the insert block 43. In the present embodiment, the contact block 46 is also divided into a plurality of parts.

And when the shape of a light-guide plate is changed, it is the same as that of embodiment of FIG. 1 thru | or 6 also about the point which can replace | exchange each block. That is, after the injection compression molding die 65 is removed from the fixed plate and the movable platen, the movable die 66 side has brackets 37, 39, cavity side surface forming blocks 29, 30, 31, core base block 17, and cavity main surface forming block. Remove 18 bolts in order and disassemble. Then, the cavity main surface forming block 18 and the cavity side surface forming blocks 29, 30, and 31 corresponding to the light guide plate to be molded next are replaced. Further, on the fixed mold 67 side, the contact block 46 and the cavity main surface forming block 42 are exchanged from the mold main body 41 to the cavity main surface forming block 42 and the contact block 46 corresponding to the light guide plate to be formed next.

6 to 9, the molded light guide plate has the same area, and only the cavity main surface forming block 18 is used to change the plate thickness, the reflective surface, the light exit surface pattern, and the like. In some cases, the light incident surface forming block 35 may be replaced in order to replace the light incident surface.

Next, still another embodiment shown in FIGS. 10 and 11 will be described. FIG. 10 is a cross-sectional view of a light guide plate injection compression mold of yet another embodiment, and FIG. 11 is a cross-sectional view of a light guide plate injection compression mold of yet another embodiment. It is a figure which shows the state which replaced the block in order to shape | mold an optical plate. The injection compression mold 71 of the embodiment shown in FIGS. 10 and 11 is a so-called inlay mold. As a feature of the injection compression mold 71, one of the cavity side surface forming block 93 and the cavity main surface forming block 76 is disposed on the fixed mold 80 and the other is disposed on the movable mold 72. In this way, both are arranged in different molds. The core base block 74 is fixed to the mold main body 73 of the movable mold 72 by bolts 75, and the cavity main surface forming block 76 that forms the cavity main surface forming surface 76 a on the front surface is formed from the back side by the bolts 77. It is fixed. The cavity main surface forming block 76, the core base block 74, and the mold main body 73 are formed so as to communicate with the coolant flow paths 78a, 78b, and 78c. Further, a runner forming block 79 on which an ejector ejecting pin or the like is disposed is fixed to the mold main body 73 with a bolt or the like (not shown).

On the other hand, the fixed mold 80 is provided with a nozzle contact portion 82 on the fixed platen side of the mold main body 81 and is connected to a manifold block 83 of a hot runner. The manifold block 83 is connected to a hot runner nozzle 84, and a valve gate 86 that is opened and closed by a cylinder 85 is disposed in the hot runner nozzle 84. A runner forming block 87 is disposed around the hot runner nozzle 84. A cavity main surface forming block 88 that forms a cavity main surface forming surface 88 a is fixed by a bolt 89 at the approximate center of the mold main body 81 on the movable mold 72 side. The cavity main surface forming block 88 and the mold main body 81 are communicated with cooling medium flow paths 90a and 90b.

A frame base 91 is fixed by a bolt 92 so as to surround the cavity main surface forming block 88 on the periphery of the mold body 81 on the movable mold 72 side. A cavity side surface forming block 93 is attached by bolts 94 to the movable base 72 side of the frame base 91. In this embodiment, the cavity side surface forming block 93 has a frame shape, but the divided ones may be integrated to form a frame. The movable mold may be provided with a concave cavity main surface forming block and a cavity side surface forming block, and the fixed mold may be provided with a convex cavity main surface forming block.

When the injection compression molding die 71 is used to change the molding of the light guide plate having a small area to the molding of the light guide plate having a large area, the example of FIG. Exchange. That is, the injection compression mold 71 is removed from an injection compression molding machine (not shown), the core base block 74 and the cavity main surface forming block 76 are removed from the mold main body 73 on the movable mold 72 side, and the area shown in FIG. The large cavity main surface forming block 76 is replaced. Also, the cavity main surface forming block 88, the cavity side surface forming block 93, and the frame base 91 are removed from the mold main body 81 or the like on the stationary mold 80 side, and the cavity main surface forming block 88 having a large area shown in FIG. The corresponding cavity side surface forming block 93 and frame base 91 are replaced.

Next, molding by another embodiment of an injection compression molding die 71 will be described. As shown in FIG. 10 and FIG. 11, the inlay type injection compression molding die 71 is formed with respect to the concave portion constituted by the cavity main surface forming block 88, the frame base portion 91, and the cavity side surface forming block 93 of the fixed die 80. Thus, the cavity main surface forming block 76 of the movable mold 72 is fitted to form the cavity C. A cavity side surface forming block 93 is provided so that the relative position can be changed in the mold opening and closing direction with respect to the cavity main surface forming block 76 by the movement of the movable mold 72 by a mold clamping device (not shown). Therefore, the injection compression mold 71 is also within the scope of the present invention. Then, before and after the injection is performed, the movable mold 72 advances to reduce the volume of the cavity C and compress the molten resin in the cavity C as in the embodiment of FIGS. .

The present invention is not enumerated one by one, but is not limited to that of the above-described embodiment, and it goes without saying that those skilled in the art also apply modifications made in accordance with the spirit of the present invention. is there. The category of the light guide plate of the present invention includes all plate-like bodies through which light passes, such as a light diffusion plate. The resin used for forming the light guide plate has been described as an example of polycarbonate, but other resins may be used as long as they are excellent in optical performance. Examples thereof include methacrylic resin and cycloolefin polymer resin.

The light guide plate in the present embodiment has been described with respect to an injection compression molding method in which the movable mold is temporarily retracted at the time of injection. However, when the plate thickness is about 0.2 to 0.5 mm, the injection press type is used. It is also assumed that the injection compression molding mold and the injection compression molding method are used. Further, the injection compression molding die and the injection compression molding method may be those that are not opened and closed in the horizontal direction but opened and closed in the vertical direction.

The method for disassembling and assembling each block of the injection compression molding die is not limited to the above embodiment, and the position, direction, number, etc. of the bolts for fixing each block are not limited. Moreover, a part of each block may be assembled | attached by a pin or a fitting, without using a volt | bolt. Further, by replacing the cavity main surface forming block and the like, the flat light guide plate and the wedge light guide plate can be formed in the same mold.

It is sectional drawing of the injection compression molding metal mold | die of the light-guide plate of this embodiment, Comprising: It is a figure which shows the state at the time of type | mold contact. It is sectional drawing of the injection compression molding metal mold | die of the light-guide plate of this embodiment, Comprising: It is a figure which shows the state when the mold is clamped and the cavity volume reduces. It is a front view of the movable metal mold | die of the injection compression molding metal mold | die of the light-guide plate of this embodiment. It is sectional drawing of the injection compression molding metal mold | die of the light guide plate of this embodiment, Comprising: It is a figure which shows the state which replaced the block in order to shape | mold a different light guide plate. FIG. 5 is a front view of the movable mold in FIG. FIG. 6 is a chart showing the injection compression molding method for the light guide plate of the present embodiment. It is sectional drawing of the injection compression molding metal mold | die of the light-guide plate of another embodiment, Comprising: It is a figure which shows the state at the time of type | mold contact. It is sectional drawing of the injection compression molding metal mold | die of the light-guide plate of another embodiment, Comprising: It is a figure which shows the state at the time of mold clamping and the cavity volume reducing. It is a front view of the movable metal mold | die of the injection compression molding metal mold | die of the light-guide plate of another embodiment. It is sectional drawing of the injection compression molding metal mold | die of the light-guide plate of another embodiment. It is sectional drawing of the injection compression molding metal mold | die of the light-guide plate of another embodiment, Comprising: It is a figure which shows the state which replaced the block in order to shape | mold a different light-guide plate.

Explanation of symbols

11, 65, 71 Injection compression molding die 12, 66, 72 Movable die 13, 67, 80 Fixed die 15, 41, 73, 81 Mold body portion 16 Core portion 17, 74 Core base block 18, 42, 76, 88 Cavity main surface forming block 18a, 42a, 76a, 88a Cavity main surface forming surface 22 Movable frame portion 29, 30, 31, 93 Cavity side surface forming block 29a, 30a, 31a Cavity side surface forming surface C Cavity H Gap

Claims (7)

In the injection compression molding mold of the light guide plate in which the distance between the cavity main surface forming surface of the movable mold and the cavity main surface forming surface of the movable mold is variably formed,
A cavity main surface forming block that forms the cavity main surface forming surface, and a cavity side surface forming block that can be changed relative to the cavity main surface forming block at least in the mold opening / closing direction are provided in a replaceable manner. An injection compression molding die for a light guide plate, characterized by being made. 2. The injection compression molding die for a light guide plate according to claim 1, wherein a block forming at least one side of the cavity side surface forming block is urged by a pressing unit with respect to the cavity main surface forming block. 3. The injection compression molding die for a light guide plate according to claim 1, wherein the light incident surface forming block is replaceably disposed with respect to the cavity side surface forming block. 2. The light guide plate according to claim 1, wherein one of the cavity side surface forming block and the cavity main surface forming block is disposed in a fixed mold, and the other is disposed in a movable mold. Injection compression mold. Using an injection compression molding mold of a light guide plate in which the distance between the cavity main surface forming surface of the movable mold and the cavity main surface forming surface of the fixed mold is variably formed,
A cavity main surface forming block that forms the cavity main surface forming surface and a cavity side surface forming block that is provided so that the relative position can be changed at least in the mold opening / closing direction with respect to the cavity main surface forming block are exchanged. An injection compression molding method for a light guide plate, characterized in that a different light guide plate is formed according to a mold. The cavity side surface forming block and the cavity main surface forming block are both disposed in either the fixed mold or the movable mold, and the removal order of the blocks is determined by removing the cavity side surface forming block and then the cavity main surface. 6. The method of injection compression molding of a light guide plate according to claim 5, wherein the forming block is removed. The light guide plate according to claim 5 or 6, wherein the cavity main surface forming block is changed to a cavity main surface forming block having a different plate thickness, thereby forming light guide plates having different plate thicknesses. Injection compression molding method.

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