JP2002036323A - Method for molding thin plate member with wedge-shaped cross section and mold clamping device for molding the thin plate member with wedge shaped cross section - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new injection molding method which can accurately produce a thin plate member having a wedge-shaped cross section such as a light guide plate for a liquid crystal display, while keeping stable quality. SOLUTION: After a molten resin is injected into a molding cavity 22 which is formed between the mold mating surfaces of a movable mold 16 and a fixed mold 14 and has a thickness larger than an aimed plate thickness, the relative inclination angle between the cavity forming surfaces 30 and 44 of the molds 14 and 16 is changed to set up the inclined surface angle of the wedge-shaped cross section, the fixed mold 14 and the movable mold 16 are mold clamping- displaced to approach each other to set up the plate thickness, and the aimed thin plate member having the wedge-shaped cross section is compression-molded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to injection molding of a resin molded article having a thin plate shape with a wedge-shaped cross section by changing the thickness of the sheet from one edge portion facing the other to the other edge portion. For example, the present invention relates to a method of forming a thin plate member having a wedge-shaped cross-section and a mold clamping method which can be advantageously applied when forming a light guide plate or the like for a lighting device used for a backlight or the like of a liquid crystal display device. The present invention relates to an apparatus and a molding die.

[0002]

2. Description of the Related Art A liquid crystal display device used for a personal computer, a word processor, a car navigation system, a liquid crystal television, a liquid crystal video, a liquid crystal DVD, etc. has a backlight disposed on the back side of the liquid crystal panel and is projected from the backlight. Light is transmitted through the liquid crystal panel to perform light control, thereby causing each of the dots set in the liquid crystal panel to emit light. In addition, since a backlight employed in such a liquid crystal display device needs to irradiate the entire surface of the liquid crystal panel widely and uniformly, the backlight generally has a planar shape over substantially the entire surface of the liquid crystal panel and is opposed to the liquid crystal panel. It has a thin plate shape with a wedge-shaped cross section in which the plate thickness gradually changes from one edge to the other edge, and the outer peripheral end face on the thick side of the light guide plate is supplied from a cold cathode discharge lamp or the like. The projected light is guided through the light guide plate to substantially the entire surface of the liquid crystal panel and irradiated.

Conventionally, a light guide plate employed in a liquid crystal display device has conventionally been provided in a fixed mold with respect to a molding cavity formed between a mold mating surface of a fixed mold and a movable mold. It is manufactured by injection-filling a molten resin material such as methacrylic resin from the runner, but the performance of such a light guide plate directly affects the performance of the liquid crystal display device, and stabilizes the excellent light guide performance. Therefore, it is important to maintain high dimensional accuracy of the light guide plate as a molded product, and to prevent sink marks, cavities, cloudiness, poor transparency, flow marks, and the like.

However, in recent years, the area of the light guide plate has become larger and the thickness thereof has become smaller with the increase in screen size and thickness of the liquid crystal display device. It is difficult to completely fill the molten resin material over the entire area, and due to poor filling or flow of the molten resin material into the molding cavity, molding defects such as sink marks, cavities, cloudiness, poor transparency, flow marks, etc. There has been a problem that defects such as poor pattern transfer on the light guide plate surface are likely to occur.

More specifically, for example, when a light guide plate having a thinner end portion having a thickness of 0.5 mm or less is to be injection-molded with methacrylic resin, the molten resin is injected into a molding cavity and simultaneously with a mold. The non-fluid resin skin layer formed on the mold surface due to the contact resistance of
Since it reaches 0.3 mm, the flow of the molten resin material in the molding cavity becomes substantially impossible from the initial stage, and poor filling or transfer failure of the resin material at the thin side end is likely to occur, A stable molding operation cannot be expected.

[0006]

Here, the present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a thin plate having a wedge-shaped cross section, such as a light guide plate for a liquid crystal display device. It is an object of the present invention to provide a novel injection molding method for a thin plate member having a wedge-shaped cross section, which can produce a member with stable quality and high precision.

Further, the present invention can be advantageously employed also in carrying out such an injection molding method for a thin plate member having a wedge-shaped cross section according to the present invention.
It is another object of the present invention to provide a mold clamping apparatus for forming a thin plate member having a novel structure, which can be manufactured with high precision and stable quality under excellent productivity.

Further, the present invention is suitably adopted in such a mold clamping apparatus for forming a thin plate member having a structure according to the present invention, and can advantageously produce a target thin plate member having a wedge-shaped cross section. It is another object of the present invention to provide a molding die having a novel structure that can be used.

[0009]

An embodiment of the present invention which has been made to solve such a problem will be described below. The components employed in each of the embodiments described below can be employed in any combination as possible. In addition, aspects or technical features of the present invention are not limited to those described below, but are described in the entire specification and drawings, or based on the invention ideas that can be understood by those skilled in the art from the descriptions. It should be understood that it is recognized on the basis of.

That is, the feature of the method of molding a thin plate member having a wedge-shaped cross section according to the present invention is that a thin plate-shaped molding cavity formed by extending between a fixed die and a movable die mating surface is melted. When a thin plate member having a wedge-shaped cross section is formed by injection-filling a resin material and cooling and solidifying, a thickness larger than a target plate thickness dimension between the fixed die and the movable die at the mating surface. After forming the molding cavity with dimensions and injecting and filling the molten resin material into the molding cavity, the relative inclination angle of the cavity forming surface between the fixed mold and the movable mold is changed, and the fixed mold is fixed. The mold and the movable mold are relatively displaced in the approaching direction so as to compression-mold a thin plate member having a wedge-shaped cross section of a target plate thickness.

According to the method of the present invention, after a molten resin material is injected and filled into a molding cavity formed with a thickness larger than the intended thickness of the light guide plate, the fixed mold and the movable mold are formed. Are relatively inclined, and the fixed mold and the movable mold are clamped to form a molding cavity corresponding to the target light guide plate dimensions.

Therefore, even when the plate thickness of the injection molded article is extremely small, when the molten resin material is injected and filled, the thickness dimension of the molding cavity is set large, so that the entire molding cavity is formed. The molten resin material can be easily and stably filled. In addition, after the molten resin material is filled into the molding cavity, the thickness dimension of the molding cavity is reduced and a compression pressure is applied, so that the molten resin material is more reliably filled into the molding cavity, and the molded product is formed. Can be further improved in the material and the dimensional accuracy. In particular, after the molten resin material is filled into the molding cavity, the molding cavity has a desired wedge-shaped cross section. The resin material can be easily filled, so that even a thin plate member having a thin wedge-shaped cross section, which has been difficult in the past, can be stably manufactured with excellent quality. .

The method of the present invention is not limited to a light guide plate used in a liquid crystal display device or the like, but has various plane shapes such as a rectangle, a polygon, a circle, and an ellipse, and has a thickness dimension thereof. Can be applied to the formation of various thin plate members having a wedge-shaped cross section that is gradually changed between the opposite end portions. Further, in the present embodiment, the material of the synthetic resin material used is not particularly limited, and may be methacrylic resin (PMMA) conventionally used as a molding material for the light guide plate, or may be depending on the use of the thin plate member. An opaque synthetic resin material can also be used. In particular,
According to this aspect, even when the fluidity of the synthetic resin material is poor, since good moldability of the thin plate member is realized,
For example, in the light guide plate, instead of methacrylic resin widely used in the past, polycarbonate (PC) having more excellent heat resistance and the like, and cycloolefin resin such as ZEONEX and ZEONOR (trade name) are easily adopted. As a result, the degree of freedom in selecting materials and characteristics can be improved.

Further, in the molding method according to the present invention, after the molten resin material is injected and filled into the molding cavity, the deformation of the molding cavity to the desired inclination angle of the wedge-shaped cross section and the desired plate thickness dimension are performed. It is also possible to simultaneously change the thickness dimension of the molding cavity of
In consideration of molding conditions, dimensions and the like, it is also possible to perform either one first and then the other.

[0015] In particular, in the molding method according to the present invention as described above, (a) the thickness of the plate formed between the fixed die and the movable die is larger than the target plate thickness. After the molten resin material is injected and filled into the molding cavity having a thickness dimension, first, the relative inclination angle of the cavity forming surface in the fixed mold and the movable mold is changed to obtain the desired inclined surface having a wedge-shaped cross section. By setting the angle, and then moving the fixed mold and the movable mold relatively to each other in the approach direction, and setting the target plate thickness dimension,
A method of forming a thin plate member by compression-forming a thin plate member having a wedge-shaped cross section; and (b) a thickness dimension larger than a target plate thickness dimension formed between the mating surfaces of the fixed die and the movable die. After the molten resin material is injected and filled into the molding cavity, while changing the relative inclination angle of the cavity forming surface in the fixed mold and the movable mold so as to give the desired inclined surface angle of the wedge-shaped cross section. At the same time, a method of forming a thin plate member for compressively forming a thin plate member having a wedge-shaped cross section by displacing the fixed die and the movable die relatively in the direction of approach so as to give a target plate thickness dimension. Any of the above can be suitably adopted. If any one of the molding methods (a) and (b) is adopted, the molding resin can be stably filled with the molten resin material, and a compressive force can be applied to the filled resin material. Can be advantageously exerted.

A feature of the first aspect of the present invention relating to a mold clamping device for forming a thin plate member having a wedge-shaped cross section is that a fixed plate on which a fixed mold is mounted and a fixed plate arranged opposite to the fixed plate. And a movable plate on which a movable mold is mounted on a surface facing the fixed plate.
Driving in the direction of separation to open / close and clamp the fixed mold and the movable mold, forming a thin plate-shaped molding cavity that spreads in a wedge-shaped cross section between the fixed mold and the movable mold. In the mold clamping apparatus for forming a thin plate member having a wedge-shaped cross section, the movable mold is mounted on the movable plate so as to be tiltable around a tilt axis orthogonal to a mold center axis extending in the mold opening and closing direction. In addition, there is provided a tilt driving means for driving the movable mold around the tilt axis to adjust the tilt angle.

In the mold clamping device having such a structure according to this aspect, the movable mold is tilted around the tilt axis so that the cavity forming surfaces of the movable mold and the fixed mold which are opposed to each other are formed. The relative inclination angle can be adjusted, and by setting the tilt angle of the movable mold about the tilt axis, the inclination angles of both side surfaces of the thin plate member can be easily adjusted and set.

Therefore, after injecting and filling a resin material into a molding cavity formed between the mold mating surfaces of the fixed mold and the movable mold, the opposing cavity forming surface is formed up to the target wedge angle of the thin plate member. Since the relative inclination can be made easily, the injection molding method of the thin plate member according to the present invention as described above can be easily performed by employing the mold clamping device having the structure according to the present aspect. It is possible.

According to a second aspect of the present invention, which relates to a mold clamping apparatus for molding a thin plate member having a wedge-shaped cross section, in the molding mold clamping apparatus having a structure according to the first aspect, the tilt driving means is provided. A mold opening / closing drive unit and a mold clamping drive unit for performing the mold opening / closing operation and the mold clamping operation of the fixed mold and the movable mold, and the mold opening / closing drive unit and the mold clamping drive unit. It is characterized in that the operation can be controlled independently of. In this embodiment, the relative inclination angle of the cavity forming surface between the fixed mold and the movable mold that are opposed to each other in the plate thickness direction,
The movable mold can be adjusted independently of the drive control of the fixed mold relative to the fixed mold in the compression direction, and the control of the inclination angle and the thickness of the molding cavity can be easily performed with great flexibility. It becomes possible.

Further, a third aspect of the present invention relating to a mold clamping apparatus for forming a thin plate member having a wedge-shaped cross section is a mold clamping apparatus having a structure according to the second aspect, wherein the tilting driving means comprises: Arranged on both sides of the mold center axis in a direction perpendicular to the tilting axis, each is supported by the movable plate, and the movable mold is attached to the movable plate in the mold opening / closing direction. It is characterized in that it includes a plurality of tilt actuators that are relatively driven in the approach / separation directions. In this aspect, the tilting actuators are supported by the movable platen, so that the tilting actuators allow the molding cavity surface of the movable mold to be independent of the compression operation of the movable platen against the fixed platen. The tilting operation can be easily performed around the tilting axis.

A feature of the present invention relating to a mold for forming a thin plate member having a wedge-shaped cross section is that the thin plate member according to the present invention has a structure according to any one of the first to third aspects. A pair of wedge-shaped molding cavities for forming a thin plate member having a wedge-shaped cross-section, which is mounted on a mold clamping device and forms a thin-walled molding cavity extending in a wedge-shaped cross-section between the mating surfaces. Side plate, on the cavity forming surface of either the movable mold or the fixed mold, projecting on both sides opposed to each other in one direction,
By means of these side plates, one of the movable mold and the fixed mold is sandwiched from both sides of the cavity forming surface at the time of mold matching, while a pair forming the thin side end surface and the thick side end surface in the molding cavity. A slide plate having a length extending over the opposing surfaces of the pair of side plates so as to extend and contract in one of the movable mold and the fixed mold. By bringing the surface into contact with the other cavity forming surface of the movable mold and the fixed mold, a pair of side plates and a slide plate is provided between the opposed surfaces of the fixed mold and the movable mold. Is formed so as to form a molding cavity in the form of a thin plate spreading in a wedge-shaped cross section.

In such a molding die having the structure according to the present invention, even when the relative inclination angle between the fixed die and the movable die changes, one of the fixed die and the movable die protrudes. The fixed end of the fixed mold and the movable mold are ensured while maintaining the hermeticity of the molding cavity by maintaining the protruding tip of the slide plate provided in contact with the other of the fixed mold and the movable mold. The relative inclination angle and thickness dimension of the cavity forming surface in the molding cavity formed between the mold matching surfaces can be easily changed. Therefore, by employing such a molding die, the method of manufacturing a thin plate member having a wedge-shaped cross section according to the present invention as described above can be advantageously performed.

Further, since the thickness of the molding cavity can be changed and set by allowing the change in the projecting height of the slide plate, a single molding die is used to change the thickness of the molding cavity. It is also possible to form a molding cavity having the same size, and to form a thin plate member having the required thickness.

In the molding die according to the present invention, there is provided an urging means for urging the pair of slide plates in a direction protruding from the movable die or the fixed die, respectively. Is desirable. By adopting such an urging means, even when the relative inclination angle of the fixed mold and the movable mold and the dimension between the opposed surfaces change,
The protruding tip of the slide plate protruding from one of the fixed mold and the movable mold can be stably maintained in a contact state with the other of the fixed mold and the movable mold. Thus, it is possible to more stably form a molding cavity having a desired shape.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 shows an overall schematic structure of a mold clamping apparatus 10 in which an injection mold having a structure according to the present invention is mounted, and FIGS. An enlarged vertical section of the part is shown. Such an injection molding die is a die for injection-molding the light guide plate 12 as shown in FIG. 4, and includes a fixed die 14 and a movable die 16, and includes a light guide plate. At the time of injection molding of 12,
The fixed cavities 18 and the movable pedestals 20 of the mold clamping device 10 are mounted on each other and are mutually mold-matched as shown in FIG. 5, so that a molding cavity 22 is formed between their mold mating surfaces. It has become. Note that, in the following description, the up-down direction refers to the up-down direction in FIG.

More specifically, the mold clamping device 10 includes a plurality of (four in the present embodiment) arranged in parallel with the mold opening and closing direction, as shown in FIG. A fixed plate 18 is attached to one end of the rod-shaped tie bar 24 in the longitudinal direction.
Is fixed, and the pressure receiving plate 26 is
Are fixed, and these fixed plate 18 and pressure receiving plate 26
They are fixed on a base (not shown) so as to face each other at a predetermined distance. A movable plate 20 having a substantially rectangular block shape is provided between the opposed surfaces of the fixed plate 18 and the pressure receiving plate 26.
The movable platen 20 is guided by the tie bars 24 and is movably supported between the opposing surfaces of the movable platen 20 and the pressure receiving plate 26 by inserting the tie bars 24 into the four corners. I have. Further, the pressure receiving plate 26 is provided with a main cylinder mechanism 28 composed of a hydraulic cylinder mechanism, and a main ram 29 of the main cylinder mechanism 28 is protruded from the pressure receiving plate 26 toward the movable platen 20 so that the movable platen 20. As a result, the driving force of the main cylinder mechanism 28 is exerted on the movable platen 20,
The movable platen 20 is driven in the approaching / separating direction with respect to the fixed platen 18 to perform a mold opening / closing operation and a mold clamping operation. That is, in the present embodiment, the main cylinder mechanism 28 constitutes a mold opening / closing drive unit and a mold clamping drive unit. The main cylinder mechanism 28 includes a single hydraulic cylinder mechanism,
A conventionally known booster-ram type hydraulic cylinder mechanism or the like can be suitably used.

On the other hand, the fixed mold 14 constituting the molding mold
Has a thick, substantially rectangular block shape as a whole, and has a flat fixed-side cavity forming surface 30 for forming the molding cavity 22 on one surface.
The sprue bush 3 is located on the center axis of the fixed mold 14.
2 is assembled, and the sprue hole of the sprue bush 32 forms a runner 34 for guiding the molten resin material to the molding cavity.

The fixed mold 14 is fixed to the fixed plate 18 on the surface opposite to the fixed-side cavity forming surface 30.
The mold mounting surface, that is, the surface facing the movable platen 20 is overlapped and fixed with bolts or the like,
It is detachably attached. As a result, the fixed mold 14 moves the fixed-side cavity forming surface 30 to the movable platen 20.
It is attached to the side. A nozzle insertion hole 36 is provided in the center of the fixed platen 18 on which the fixed mold 14 is mounted. As is well known, the nozzle 38 of the injection device having a separate structure is connected to the nozzle insertion hole 36. And the nozzle is touched to the sprue bush 32 of the fixed mold 14, whereby the molten resin material is supplied to the runner 34 from the injection device.

On the other hand, the movable mold 16, which constitutes a forming mold in cooperation with the fixed mold 14, has a structure in which a support block 42 is overlapped on a movable mold body 40 and fixed to each other. Have been. The movable mold body 40 has a thick, substantially rectangular flat plate shape as a whole, and one surface of the movable mold body 40 cooperates with the fixed-side cavity forming surface 30 of the fixed mold 14 to define the molding cavity 22. It is a flat movable side cavity forming surface 44. In addition, the movable mold body 40 includes:
A pair of side plates 46, 46 protruding toward the plate thickness direction are integrally formed at both end portions in the width direction (vertical direction in FIG. 3) that is the left-right direction. These side plates 46, 46 are each formed continuously over the entire length of the edge of the movable mold body 40, have a substantially constant protruding height over the entire length, and face each other. The dimensions between the inner surfaces are also substantially constant throughout.

The movable block body 40 has a support block 42 superimposed on a surface opposite to the side of the side plates 46, 46 protruding. Like the movable mold body 40, the support block 42 has a thick, substantially rectangular flat plate shape as a whole.
A pair of housing cavities 48, 48 are formed between the overlapping surfaces of the movable mold body 40 and the upper and lower ends thereof. Then, a pair of slide plates 50, 50 are assembled so as to protrude from the housing cavities 48, 48 onto the movable cavity forming surface 44 of the movable mold body 40. The slide plate 50 has a flat plate-like vertical plate portion 5 with respect to a support portion 52 having a rectangular block shape.
The supporting portion 52 is accommodated in the accommodating cavity 48 so as to be reciprocally movable in the shape of a piston in the thickness direction of the movable mold 16, and the vertical plate portion 54 is provided. It is positioned so as to project from the accommodation space 48 onto the movable-side cavity forming surface 44 through an insertion hole 56 formed in the movable mold body 40.

The storage cavities 48, 48 and the slide plates 50, 50 are continuous in a fixed cross section over substantially the entire length of the movable mold 16 in the vertical direction (vertical direction in FIG. 1). Is formed in a shape, whereby
On the movable-side cavity forming surface 44, a pair of vertical plate portions 54, 54 extend over the entire length between a pair of side plates 46, 46 projecting from both left and right edges, respectively. The two end faces of each vertical plate portion 54 are disposed so as to be slidably contacted with the opposing inner surfaces of the side plates 46, 46. In particular, in the present embodiment, the movable-side cavity forming surface 44 of the slide plate 50 is used.
The maximum protruding height of the vertical plate portion 54 is determined by the side plate 4
The projecting height of the vertical plate portion 54 is set so as to be smaller than the projecting height of the vertical plate 6. In addition, the outer peripheral shape of the support portion 52 is set corresponding to the inner peripheral surface shape of the accommodation space 48, and the thickness of the support portion is made sufficiently large, so that the vertical plate portion 54 The protruding height can be changed while maintaining a substantially vertical state with respect to the cavity forming surface 44.

Further, in each of the accommodating cavities 48, an appropriate number of coil springs 58 as urging means for urging the slide plate 50 in the projecting direction are accommodated in a compressed state in the mold thickness direction. The slide plate 50 is always urged in the projecting direction by the urging force of the coil spring 58, and is elastically protruded. Thus, when a pressing force is applied to the distal end surface of the vertical plate portion 54 of each slide plate 50,
The projecting height can be elastically changed against the urging force of the coil spring 58.

The movable die 16 having such a structure is mounted on the movable platen 20 on the back surface of the support block 42 (the surface opposite to the surface on which the movable die body 40 overlaps).
Mounted against.

The movable plate 20 to which the movable mold 16 is attached is located at the center of the surface facing the fixed plate 18 and has a constant semicircular cross-sectional shape and a predetermined length in the left-right direction. An extended Kamaboko-shaped support projection 60 is integrally formed. On the other hand, the support block 4 of the movable mold 16
2, a trough-shaped or groove-shaped mounting recess 62 extending continuously in the left-right direction with a semicircular constant cross-sectional shape corresponding to the shape of the outer peripheral surface of the support protrusion is formed at a central portion of the back surface. I have. The mounting recess 62 of the support block 42
, The support projection 60 of the movable platen 20 is fitted,
The protruding distal end surface of the support projection 60 is slidably abutted against the inner peripheral surface of the mounting recess 62, and is based on the sliding action between the support projection 60 and the abutment surface of the mounting recess 62. The mounting angle (tilt angle) of the support block 42 to the movable platen 20 can be changed around the tilt center axis 80 with the center axis of the arc-shaped outer peripheral surface of the support block 42 as the tilt center axis 80. The support block 42 is combined with the movable platen 20.

Further, the support projection 60 of the movable platen 20
A substantially T extending a predetermined length in the circumferential direction at a substantially central portion in the length direction
A dovetail groove 64 having a V-shaped cross section is formed.
The leg 68 of the sliding member 66 slidably fitted to the projection 4 protrudes from the outer peripheral surface of the support projection 60 and is screwed and fixed to the support block 42. Thereby, the movable platen 20 of the support block 42 based on the sliding action between the contact surface of the support projection 60 and the mounting recess 62.
The movable mold 16 is mounted so as not to be detached from the movable platen 20 while allowing a change operation of the mounting angle (tilt angle) with respect to the movable plate 20.

Further, the movable platen 20 is located at four positions on the back side (opposite to the mounting surface of the movable mold 16) on the circumference around the center axis, and each of the movable plates 20 is a tilting actuator. Cylinder mechanism 70 is provided.
The tilting cylinder mechanism 70 is constituted by a hydraulic cylinder mechanism smaller than the main cylinder mechanism 28, and its piston rod 72 is inserted through an insertion hole 74 formed in the movable board 20 to the surface side of the movable board 20. It is protruding. The protruding tip of the piston rod 72 of each of the tilting cylinder mechanisms 70 is connected to the movable mold 16.
It is locked to a locking portion 76 protruding from the back side of the (support block 42). The locking hole 78 of the piston rod 72 in each locking portion 76 is
6 is formed in an arc shape so as to allow tilting.

Thus, two tilting members are disposed on both sides of the tilting center axis 80 perpendicular to the center axis of the mold clamping device 10 (in this embodiment, the center axis of the main cylinder mechanism 28). By driving the cylinder mechanism 70 relatively in the projecting direction and the retracting direction, the movable mold 16
, A tilt driving force about the tilt center axis 80 is exerted. In addition, by detecting or controlling the relative position of the piston rod 72 in each of the two tilting cylinder mechanisms 70 positioned on both sides of the tilting center axis 80, the mold clamping device 10 The tilt angle of the movable mold with respect to the center axis can be detected or adjusted and controlled.

When the movable mold 16 is mounted on the movable platen 20 as described above, the fixed mold 14 and the cavity forming surfaces 30 and 44 of the movable mold 16 are aligned with the center axis of the mold clamping device 10. Are disposed above each other. Also, a pair of side plates 46, 4 protruding from the movable mold 16 are provided.
6 are protruded toward the fixed mold 14 side, and are slidably fitted on both sides in the width direction of the fixed mold 14 with the fixed-side cavity forming surface 30 interposed therebetween. I have. In other words, the fixed mold 14 is fitted and positioned between the opposing surfaces of the pair of side plates 46, 46 in the movable mold 16. Furthermore, the pair of slide plates 50, 50 protruding from the movable mold 16 have their protruding tip surfaces elastically abutting against the fixed-side cavity forming surface 30 of the fixed mold 14 over the entire length. Being touched.

The fixed-side cavity forming surface 30 of the fixed mold 14 is slightly positioned at a position corresponding to the slide plate 50 on one side (the upper side in the present embodiment) projecting from the movable-side cavity forming surface 44. A substantially triangular groove-shaped contact groove 82 having an inclined surface is formed. As a result, as shown in FIG.
When the movable die 16 is tilted and moved in a state where the two dies 14 and 16 are aligned with each other, the protruding front end surface of the movable die 16 is positioned with respect to the inclined surface of the contact groove 82 on the center side (in other words, the inside angle). Part)
, The occurrence of a gap in the contact portion between the fixed-side cavity forming surface 30 and the protruding tip surface of the slide plate 50 is prevented, and the molding cavity 22 is formed stably. I have.

As a result, the cavity forming surface 3 of the fixed mold 14 and the movable mold 16 which are opposed to each other at a predetermined distance.
A pair of side plates 46, 46 around 0, 44
And the slide plates 50, 50, so that the molding cavity 22 of the light guide plate 12, which is partitioned from the external space, is formed between the opposing surfaces of the cavity forming surfaces 30, 44.

In the mold clamping apparatus 10 having such a structure, the movable mold 16 is tilted around the tilt center axis 80 by the tilt cylinder mechanism 70 to form the movable-side cavity of the movable mold 16. The inclination angle of the surface 44, and thus the movable-side cavity forming surface 4 of the movable mold 16 with respect to the fixed-side cavity forming surface 30 of the fixed mold 14.
4 can be arbitrarily changed and set, and in turn, the tilt angle (wedge angle) of the wedge-shaped cross section set on both the front and back surfaces of the light guide plate to be formed is changed or adjusted. It is possible to do.

Hereinafter, a specific example of the injection molding method of the light guide plate 12 using the mold clamping device 10 will be described.

First, as shown in FIG. 5, the projecting heights of the piston rods 72, 72 are adjusted to be substantially the same by hydraulic control of the tilting cylinder mechanisms 70, 70, and the movable side cavity is adjusted. Under a state where the forming surface 44 and the fixed-side cavity forming surface 30 are substantially parallel to each other, a known high-speed mold closing operation is performed by a booster cylinder mechanism (not shown) arranged in the main cylinder mechanism 28,
Subsequently, the mold clamping operation is performed by the main cylinder mechanism 28, so that the two dies 14, 16 are matched and held in the mold clamping state. As a result, the plate-shaped molding cavity 22 whose both surfaces are substantially parallel is fixed to the fixed mold 1.
4 and the movable die 16 are formed between the mating surfaces. In other words, the temporary cavity before the target shape is replaced with the two dies 14,
It is formed between 16 mating surfaces.

Then, the molten resin material 84 is supplied to the sprue bush 32 assembled in the center hole of the fixed die 14 from the nozzle 38 of the injection device, which is brought into nozzle contact with the nozzle insertion hole 36 of the fixed plate 18, by the runner. Through 34, it is guided to the molding cavity 22 for injection filling.

Then, as shown in FIG. 6, the movable mold 16, the extension of the movable mold 16 is controlled by controlling the hydraulic pressure of each tilting thin cylinder mechanism 70, 70 to adjust the projecting height of each piston rod 72, 72. Then, the movable mold main body 40 is slid around the tilting center axis 80 to give a desired wedge angle of the molded thin plate to the molding cavity 22.

Subsequently, as shown in FIG. 7, the movable plate 20 is further driven forward (toward the fixed plate 18) by the main cylinder mechanism 28 to set a target plate thickness. Thus, a molding cavity 22 that gives a desired shape of the light guide plate 12 is formed.

Further, the mold clamping device 10 applies a mold clamping force between the fixed mold 14 and the movable mold 16 to perform the mold clamping operation, whereby the resin material 84 filled in the molding cavity 22 is clamped. Apply force to complete compression. In addition, the mold clamping force is generally set to be larger than the force in the mold opening direction exerted on the mold by the injection pressure during injection filling. Then, after the resin material 84 in the molding cavity 22 is cooled and solidified in the mold-clamped state, the mold is opened, and the molded product is released from the mold, thereby taking out the desired light guide plate 12 (see FIG. 4). Can be obtained.

In the injection molding method of this embodiment, as described above, one specific example is shown. For example, according to various molding conditions such as the type and size and shape of the resin material to be employed, The molten resin material 84 is formed in the molding cavity 22.
After the injection filling, the deformation of the molding cavity 22 to the target inclination angle of the wedge-shaped cross section and the change of the thickness dimension of the molding cavity 22 to the target plate thickness dimension may be simultaneously performed. It is possible.

Accordingly, in the light guide plate 12 obtained by such an injection molding method, first, the molten resin material 84 is injected and filled into the molding cavity 22 larger than the target plate thickness, and then the fixed mold is formed. By inclining the movable mold 14 and the movable mold 16 relatively and clamping the fixed mold 14 and the movable mold 16, the plate on the thin side edge (the upper end in FIG. 4) of the light guide plate 12 is particularly improved. Even when the thickness dimension is extremely small, the molten resin material 84 can be easily and stably filled over the entire molding cavity 22. Moreover, after the molding resin 22 is filled with the molten resin material 84, the thickness of the molding cavity 22 is reduced and a compressive pressure is applied, so that the molten resin material 84 is more reliably applied to the molding cavity 22. By being filled, the quality and dimensional accuracy of the light guide plate 12 can be further improved.

In the mold clamping device 10 having the structure according to the present invention, the movable mold 16 is connected to the movable platen 20.
By tilting around the tilt center axis 80, the relative tilt angles of the cavity forming surfaces 30, 44 of the movable mold 16 and the fixed mold 14, which are opposed to each other, can be adjusted. Accordingly, the opposing cavity forming surfaces 30, 44 can be easily inclined relative to each other up to the target wedge angle of the light guide plate 12, so that the injection molding method of the present embodiment can be advantageously performed. It becomes possible.

Further, in the fixed mold 14 and the movable mold 16 having the structure according to the present invention, the projecting tips of the slide plates 50 projecting from the movable mold body 40 are fixed to the fixed side. By maintaining the cavity forming surface 30 or the abutment groove 82 in a contact state, the sealing property of the molding cavity 22 is ensured, and the relative inclination angle and the thickness dimension of the two cavity forming surfaces 30 and 44 are maintained. Can be easily changed. And such two molds 3
0, 44, the light guide plate 12 as described above is used.
Can be advantageously carried out.

Further, since the change in the projecting height of the slide plates 50, 50 is allowed by the coil springs 58, 58, the thickness dimension of the molding cavity 22 can be appropriately changed and set. There is also an advantage that the molding cavities 22 having different thicknesses and, consequently, the light guide plate 12 having the required thickness can be molded by one movable mold 16.

Although the embodiments of the present invention have been described in detail above, they are merely examples, and the present invention is not to be interpreted in any limited manner by the specific description in the embodiments.

For example, the main cylinder mechanism 28 and the tilting cylinder mechanism 70 employed in the above embodiment are
It is not limited to the hydraulic cylinder mechanism as illustrated,
Specifically, for example, an electric actuator mechanism using a rotary motor, a linear motor, or the like, an actuator mechanism using a toggle mechanism, or the like can be appropriately adopted.

The tilting cylinder mechanism 70 does not necessarily need to be assembled to the movable mold 16,
It is also possible to assemble them.

Further, in the above embodiment, the movable mold 1
6 is disposed so as to be rotatable around a tilt center axis 80 orthogonal to the center axis of the mold clamping device, but is rotated around a tilt center axis biased with respect to the center axis of the mold clamping device. Is also good.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, the present invention can be implemented in a form in which various changes, modifications, improvements, and the like are made.
It goes without saying that all such embodiments are included in the scope of the present invention without departing from the spirit of the present invention.

[0059]

As is apparent from the above description, according to the method of the present invention, in forming a thin plate member having a wedge-shaped cross section, the molding cavity is formed into a wedge-shaped cross section after the molten resin material is filled into the molding cavity. Therefore, even at the edge where thinning is required, the molten resin material can be easily filled with the molten resin material by increasing the thickness dimension at the time of filling the molten resin material. It is possible to manufacture the thin plate member stably with excellent quality.

Further, in the mold clamping apparatus having the structure according to the present invention, the tilting angle of the movable die about the tilt axis is adjusted so that the movable die and the fixed die which are opposed to each other are positioned. The relative inclination angle of the cavity forming surface can be easily adjusted and set, and therefore, for example, the manufacturing method according to the present invention of a thin plate member having a wedge-shaped cross section as described above can be advantageously performed.

Further, in the molding die having the structure according to the present invention, the projecting tip of the slide plate protruding from one molding die abuts on the other molding die. By being maintained in the state, it is possible to easily change the relative inclination angle, thickness dimension, etc. of the cavity forming surface while securing the sealing property of the molding cavity. By adopting the method described above, for example, the method of manufacturing a thin plate member having a wedge-shaped cross section according to the present invention as described above can be advantageously performed.

[Brief description of the drawings]

FIG. 1 is a front view showing an overall schematic structure of an injection molding mold clamping device as one embodiment of the present invention.

FIG. 2 is an explanatory longitudinal sectional view of a main part of the mold clamping device for injection molding shown in FIG. 1;

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a model diagram showing a specific example of a light guide plate formed according to the method of the present invention.

FIG. 5 is an explanatory longitudinal sectional view showing one molding step in molding a light guide plate using the injection molding mold clamping device shown in FIG. 1;

FIG. 6 is an explanatory longitudinal sectional view showing one molding step in molding a light guide plate using the mold clamping device for injection molding shown in FIG. 1;

FIG. 7 is an explanatory longitudinal sectional view showing one molding step in molding a light guide plate using the injection molding mold clamping device shown in FIG. 1;

[Explanation of symbols]

 Reference Signs List 10 mold clamping device 12 light guide plate 14 fixed mold 16 movable mold 22 molding cavity

Claims (8)

[Claims] 1. A thin-walled member having a wedge-shaped cross section is formed by injection-filling a molten resin material into a molding cavity in the form of a thin plate formed by extending between a mold mating surface of a fixed mold and a movable mold and cooling and solidifying it. In molding, between the fixed mold and the mold mating surface of the movable mold,
After forming the molding cavity with a thickness dimension larger than a target plate thickness dimension and injecting and filling the molten resin material into the molding cavity, the relative positions of the cavity forming surfaces of the fixed mold and the movable mold are adjusted. In addition, the thin plate member having the wedge-shaped cross section of the target plate thickness is compression-formed by changing the fixed inclination angle and moving the fixed die and the movable die relatively in the approach direction. The method for forming a thin plate member. 2. After the molten resin material has been injected and filled into a molding cavity formed between the fixed mold and the movable mold, the molding cavity having a thickness larger than a target plate thickness. First, the relative inclination angle of the cavity forming surface between the fixed mold and the movable mold is changed to set the desired inclined surface angle of the wedge-shaped cross section. 2. The method for forming a thin plate member according to claim 1, wherein the thin plate member having a wedge-shaped cross section is compression-formed by displacing the mold in the direction of approaching to set the target plate thickness dimension. 3. After the molten resin material is injected and filled into a molding cavity formed between the fixed mold and the movable mold, the molding cavity having a thickness larger than a target plate thickness. While changing the relative inclination angle of the cavity forming surface in the fixed mold and the movable mold so as to give the target inclined surface angle of the wedge-shaped cross section, at the same time, giving the target plate thickness dimension, The method for forming a thin plate member according to claim 1, wherein the thin plate member having a wedge-shaped cross section is compression-formed by relatively displacing the fixed die and the movable die in the approaching direction. 4. A fixed plate on which a fixed mold is mounted, and a movable plate which is disposed opposite to the fixed plate and has a movable die mounted on a surface facing the fixed plate, wherein the movable plate is mounted on the fixed plate. The movable platen is driven in the approaching / separating direction to open / close and clamp the fixed mold and the movable mold. The thin plate shape spreads in a wedge-shaped cross section between the fixed mold and the movable mold. In the mold clamping apparatus for molding a thin plate member having a wedge-shaped cross section, the movable mold is moved around the movable plate with respect to the movable plate around a tilt axis orthogonal to a mold center axis extending in a mold opening and closing direction. A mold clamping device for forming a thin plate member having a wedge-shaped cross section, the device comprising a tiltable driving means mounted to be tiltable and driving the movable mold around a tilting axis to adjust a tilting angle. 5. The driving means for tilting has a separate structure from the driving means for opening and closing the mold and the driving means for closing the mold for causing the fixed mold and the movable mold to perform the mold opening / closing operation and the mold clamping operation. The mold clamping apparatus for forming a thin plate member according to claim 4, wherein the operation can be controlled independently of the mold opening / closing drive means and the mold clamping drive means. 6. The tilting driving means is disposed on both sides of the mold center axis in a direction orthogonal to the tilting axis, and the movable mold is attached to the movable platen in the mold opening / closing direction, respectively. The mold clamping device for forming a thin plate member according to claim 5, comprising a plurality of tilting actuators that are relatively driven in the approaching / separating direction. 7. A wedge-shaped cross-section which is mounted on the thin plate member-forming mold clamping device according to claim 4 and forms a thin plate-shaped molding cavity which spreads in a wedge-shaped cross-section between the mold mating surfaces. A mold for molding a thin plate member, wherein a pair of side plates forming both end surfaces of a wedge-shaped molding cavity are opposed to each other in one direction on a cavity forming surface of one of the movable mold and the fixed mold. At the time of mold matching, one of the movable mold and the fixed mold is sandwiched from both sides of the cavity forming surface by the side plates, while the thin side end surface of the molding cavity is A pair of slide plates forming a thick-side end surface can extend and contract in one of the movable mold and the fixed mold with a length spanning between opposing surfaces of the pair of side plates. By projecting, the protruding tip surfaces of the slide plates are brought into contact with the other cavity forming surface of the movable mold and the fixed mold, so that the opposing surfaces of the fixed mold and the movable mold are formed. A molding die for forming a thin plate member having a wedge-shaped cross-section, in which a pair of side plates and a slide plate define a perimeter and a thin-wall-shaped molding cavity extending in a wedge-shaped cross-section is formed. 8. The molding of a thin plate member having a wedge-shaped cross section according to claim 7, wherein biasing means for biasing the pair of slide plates in a direction protruding from the movable mold or the fixed mold, respectively, is provided. Mold.