JP2000329908A - Plastic molded goods - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rib structure improved in the shape accuracy of a transfer surface. SOLUTION: A plastic lens 30 is formed with ribs 31 in the peripheral parts of a mirror finished surface part 32 to which the transfer surface of a die cavity is transferred. A recessed part 33 formed by the incomplete transfer of the die cavity shapes facing each other is formed at the time of molding at the intersect position of the mirror finished surface part 32 of the ribs 31 and the ribs 31. Then, the shrinks of plastic resin can be selectively guided into the recessed part 33 which is the incompletely transferred part. The plastic lens 30 of a long size and a thin shape may thus be formed with low distortion and high shape accuracy. Particularly the formation of the mirror finished surface part 32 with the high accuracy is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic molded product, and more particularly, to a laser type digital copying machine, an optical scanning system of a laser printer or a facsimile apparatus, an optical apparatus such as a video camera, an optical disk, and the like. The present invention relates to a plastic molded product, particularly a plastic molded product such as a plastic lens or a plastic mirror having a rib structure.

[0002]

2. Description of the Related Art Optical elements such as a rectangular lens or a mirror having a laser beam imaging and various correction devices are used in an optical writing optical system such as a digital copying machine of a laser system, a laser printer and a facsimile machine. I have.

In recent years, these optical elements have been changed from glass to plastic in response to demands for cost reduction of products, and the shape of the optical elements has been increased depending on the required optical performance. There is a wide variety of shapes, such as a uniform thickness shape or an uneven thickness shape in the longitudinal direction.

Under such circumstances, plastic molded articles such as plastic lenses or plastic mirrors having a long or thin shape are required to maintain the shape accuracy by improving the mounting accuracy to the housing and the rigidity of the molded article. In the case of the long lens 1 as shown in FIGS. 7 and 8, a reinforcing member called a rib 2 is generally provided around the lens unit 3.

[0005] Such a manufacturing method has a low manufacturing cost, and allows an injection molding method suitable for mass production or a nest which forms a transfer surface arranged in a mold to be movable, and is filled in the mold. It is generally molded using a so-called injection compression molding method in which the movable insert advances in response to the volume shrinkage caused by cooling of the resin, thereby compensating for the pressure and ensuring the shape accuracy.

[0006] When manufacturing a plastic lens or a plastic mirror by such an injection molding method or an injection compression molding method, a resin material melted by heating is injected into a mold and then cooled and solidified. It is necessary for the resin pressure and resin temperature in the mold to be uniform in order to secure desired shape accuracy.

However, in the case of the long lens 1 having the ribs 2 as shown in FIGS. 7 and 8, since the heights of the ribs 2 in the longitudinal direction are different, the resin temperature in the mold during molding is not uniform. As a result, there has been a problem that the desired shape accuracy cannot be obtained.

In the case of producing a plastic lens or a plastic mirror by the injection compression molding method, molding can be performed with a lower injection pressure than in the injection molding method. However, if the thickness of the lens portion 3 is uneven, a difference in volume shrinkage occurs in each portion of the lens portion 3 in the longitudinal direction, and the movable insert cannot follow the volume shrinkage of the resin. In addition, since a uniform pressure cannot be applied, there is a problem that sink occurs on a part of the transfer surface and the shape accuracy is deteriorated.

Therefore, conventionally, the lens has a long shape in which the ratio of the width to the thickness is small relative to the entire length, and the lens surface has a uniform thickness in the entire length direction and a curvature in the long direction. There has been proposed a resin-molded long lens having a frame shape composed of ribs having a uniform height and a uniform thickness over the entire inner circumference and outer circumference of the lens surface (Japanese Patent Laid-Open No. Hei 5 (1993) -205).
No. 80208).

That is, this resin-molded long lens has ribs of uniform height and thickness over the entire circumference of the lens surface of the long lens, and attempts to secure the shape accuracy by equalizing the amount of shrinkage during molding. .

[0011] Further, the applicant of the present invention is a plastic member in which an area of a required longitudinal section for traversing a range where accuracy is required changes according to the longitudinal position. A plastic member or a lens portion characterized by changing the area of the extended portion of the enlarged longitudinal section so that the area of the enlarged longitudinal section including the surface is substantially uniform is formed to be long, and the lens portion A plastic lens in which the area of an effective longitudinal section that traverses an effective range is changed in the longitudinal direction, and the enlargement is performed so that the area of an enlarged longitudinal section including the effective longitudinal section obtained by extending the effective longitudinal section is substantially uniform. A plastic lens characterized by changing the area of the extension of the longitudinal section in the longitudinal direction has been proposed (Japanese Unexamined Patent Publication No. Hei 9-1997).
No. 220770).

That is, the plastic member or the plastic lens is a long lens whose lens thickness changes in the longitudinal direction. The lens portion is such that the area of the enlarged longitudinal section including the lens portion is substantially constant in the longitudinal direction. A variable shape is formed in the longitudinal direction between the rib and the rib.

[0013]

However, such a plastic molding method has the following problems.

That is, in the long resin-molded lens described in Japanese Patent Application Laid-Open No. 5-80208, if the rib shape is provided along the curvature in the longitudinal direction, the mold structure becomes complicated and processing becomes difficult. In addition, there is a problem that the effect of securing the shape accuracy by equalizing the amount of shrinkage during molding cannot be obtained for a molded product whose lens thickness changes in the longitudinal direction.

In the plastic lens described in Japanese Patent Application Laid-Open No. 9-220770, when a variable shape is formed in the longitudinal direction, it becomes difficult to mold and the thickness of the variable shape is different from that of the lens portion. In addition, the cooling and solidification of the resin at the time of molding may become unbalanced, and the accuracy of the shape may be reduced.

In view of the above, the invention according to claim 1 is an invention in which at least one of at least one of the one or more ribs formed around the one or more transfer surfaces on which the transfer surface of the mold cavity is transferred is formed. Incomplete transfer by forming a concave or convex part or an incomplete transfer part of both the concave part and the convex part formed by incomplete transfer of the opposite mold cavity shape at the time of molding at the position of To provide a plastic molded product that selectively induces sinks of plastic resin in a portion and can secure a transfer surface with low distortion and high shape accuracy even in a long and thin shape. And

According to a second aspect of the present invention, an incomplete transfer portion is provided.
By forming the transfer surface at the intersection of the rib and the surface including the transfer surface, the transfer surface is appropriately guided to the incomplete transfer portion at the intersection of the rib and the surface including the transfer surface, thereby reducing distortion on the transfer surface. An object of the present invention is to provide a plastic molded product that can be further reduced and the transfer surface shape accuracy can be further improved.

According to a third aspect of the present invention, an incomplete transfer portion is provided.
By forming two or more locations on one surface of the rib, sinks are more efficiently induced in the incomplete transfer portion, the distortion of the entire plastic molded product is further reduced, and the shape accuracy of the transfer surface is improved. An object is to provide a plastic molded product that can be further improved.

According to a fourth aspect of the present invention, a plastic molded article is formed by an injection molding method or an injection compression molding method, thereby inexpensively and effectively inducing sink marks in an incomplete transfer portion to thereby reduce distortion. It is an object of the present invention to provide a plastic molded product capable of further reducing the shape and improving the shape accuracy of the transfer surface.

According to a fifth aspect of the present invention, an incomplete transfer portion is provided.
By forming a concave part formed by local mold shrinkage with respect to the mold cavity shape facing during molding,
An object of the present invention is to provide a plastic molded product that can inexpensively and effectively induce sink marks in an incomplete transfer portion, further reduce distortion, and further improve shape accuracy of a transfer surface. .

According to a sixth aspect of the present invention, an incomplete transfer portion is provided.
By making the convex part formed by local resin pressure release to the opposite mold cavity shape at the time of molding processing, inexpensively and effectively induce sink marks in the incomplete transfer part and reduce distortion. It is an object of the present invention to provide a plastic molded product that can be further reduced and the shape accuracy of a transfer surface can be further improved.

According to a seventh aspect of the present invention, a plastic molded product is a plastic optical element having at least one of the transfer surfaces being an optical mirror surface, so that the transfer surface is appropriately guided to an incomplete transfer portion. It is another object of the present invention to provide a plastic optical element having an optical mirror surface with high shape accuracy by reducing distortion on a transfer surface serving as an optical mirror surface.

[0023]

The plastic molded article according to the first aspect of the present invention is filled in a mold cavity and molded, and one or more transfer surfaces onto which the transfer surface of the mold cavity is transferred. And a plastic molded article having one or more ribs formed on the periphery of the transfer surface, wherein the mold cavity is formed at an arbitrary position of at least one of the ribs. A recess formed by incomplete transfer of the opposite mold cavity shape during processing,
Alternatively, the above-described object is achieved by forming the incompletely transferred portions of the convex portions or the concave portions and the convex portions.

According to the above arrangement, at least one of the one or more ribs formed on the periphery of the one or more transfer surfaces onto which the transfer surface of the mold cavity has been transferred is placed at an arbitrary position on at least one of the ribs. Concave part formed by incomplete transfer of the opposite mold cavity shape during molding, or convex part, or
Since the incomplete transfer part of both the concave part and the convex part is formed,
The sink of plastic resin can be selectively guided to the incomplete transfer area, and even with long and thin plastic molded products, a transfer surface with low distortion and high shape accuracy can be secured. it can.

In the above case, for example, the incomplete transfer portion may be formed at an intersection of the surface including the transfer surface and the rib.

According to the above configuration, since the incomplete transfer portion is formed at the intersection of the rib including the transfer surface and the rib, the transfer surface is formed at the incomplete transfer portion at the intersection of the rib including the transfer surface. By appropriately inducing sink marks, distortion on the transfer surface can be further reduced, and the shape accuracy of the transfer surface can be further improved.

Further, for example, as described in claim 3, the incomplete transfer portion may be formed at two or more locations on one surface of the rib.

According to the above configuration, since two or more incomplete transfer portions are formed on one surface of the rib, sink marks are more efficiently guided to the incomplete transfer portion, and the plastic molded article is formed. The overall distortion can be further reduced, and the shape accuracy of the transfer surface can be further improved.

Further, for example, as described in claim 4, the plastic molded article may be formed by an injection molding method or an injection compression molding method.

According to the above configuration, since the plastic molded article is formed by the injection molding method or the injection compression molding method, it is possible to inexpensively and effectively induce sink marks in the incomplete transfer portion to reduce distortion. The transfer surface can be further reduced, and the shape accuracy of the transfer surface can be further improved.

Also, for example, as described in claim 5, the incomplete transfer portion is a concave portion formed by local mold shrinkage with respect to the shape of the mold cavity opposed to the molding process. You may.

According to the above arrangement, the incompletely transferred portion is formed as a concave portion formed by local mold shrinkage with respect to the shape of the mold cavity opposed to the molding process, so that it is inexpensive and effective. The sink can be induced in the incomplete transfer portion, the distortion can be further reduced, and the shape accuracy of the transfer surface can be further improved.

Further, for example, as described in claim 6, the incomplete transfer portion is a convex portion formed by local resin pressure release with respect to the shape of the mold cavity facing the molding process. There may be.

According to the above configuration, since the incompletely transferred portion is formed as a convex portion formed by locally releasing the resin pressure with respect to the shape of the mold cavity opposed to the molding process, it is inexpensive and effective. Induction of sink in the incomplete transfer area
The distortion can be further reduced, and the shape accuracy of the transfer surface can be further improved.

Also, for example, the plastic molded article may be a plastic optical element in which at least one of the transfer surfaces is an optical mirror surface.

According to the above configuration, since the plastic molded article is a plastic optical element in which at least one of the transfer surfaces is an optical mirror surface, the transfer surface is appropriately guided to the incomplete transfer portion, and the optical mirror surface is formed. The distortion on the transfer surface can be reduced, and the plastic optical element can have an optical mirror surface with high shape accuracy.

[0037]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 to 3 are views showing one embodiment of the plastic molded product of the present invention. FIG. 1 is a diagram showing the molding of a plastic molded product to which one embodiment of the plastic molded product of the present invention is applied. 1 is a front sectional view of a forming die 10 to be formed.

In FIG. 1, the molding die 10 has a cavity 15 defined by insert pieces 11 to 14, and the insert piece 11 has a vent 16 opening into the cavity 15.
Is formed. A ventilation tube 18 is connected to the ventilation passage 17, and the ventilation tube 18 is connected to a gas supply source 19 provided outside the molding die 10.

The molding die 10 includes an insert piece 11 and an insert piece 1.
2 and the part defined by the insert piece 13 and the insert piece 12 and the insert piece 14, the rib 31 of the plastic lens 30 which is a plastic molded product shown in FIGS. The opposite surfaces of the insert piece 12 and the insert piece 14 become the transfer surface, and the mirror surface portion 32 of the plastic lens 30 is formed at the transfer surface portion.

The vent 16 of the ventilation passage 17
Is the intersection of the surface of the plastic lens 30 formed by the insert piece 12 and the insert piece 14 including the mirror surface portion 32 and the rib 31 of the plastic lens 30 formed by the insert piece 11 and the insert piece 12 and the insert piece 14. Is formed in a thick portion corresponding to the above.

Next, the operation of the present embodiment will be described. In order to mold the plastic lens 30 by injection molding using the molding die 10, the resin 20 is injected and filled into the cavity 15 defined by the insertion pieces 11 to 14, and then the resin 20 is cooled and solidified. .

When the cooling and solidification of the resin 20 progresses and the resin pressure reaches a predetermined pressure, the gas supply source 19 is operated to
The ventilation port 16 is provided through the ventilation tube 18 and the ventilation passage 17.
Gas is blown onto the resin 20 from the
A space 21 is provided between the first and second walls.

When the cavity 21 is formed, the resin 20 is separated from the wall surface of the cavity 15 of the insertion piece 11.
Portion becomes a free surface and is easy to move, and it is difficult for heat of this portion to escape, and the temperature of the portion becomes higher than that of the other resin 20 in contact with the wall surface of the cavity 15.

Therefore, the resin 20 in the portion facing the gap 21 undergoes resin movement and shrinkage with priority over the resin 20 in the other portions, and the concave portion 33 is formed as shown in FIGS. .

In molding the plastic lens 30, the filling pressure of the molten resin 20 into the cavity 15 is set to a low pressure such that the internal strain does not affect the optical performance of the molded plastic lens 30. However, when molding at low pressure, when the molten resin 20 is cooled and shrunk, sinking is generated in the portion of the resin 20 separated from the wall surface of the cavity 15 so that the concave portion 33 can be appropriately formed. it can. That is, incomplete transfer of the wall surface of the cavity 15 occurs due to local mold release contraction,
Can be formed.

The vent 16 of the ventilation passage 17
Is the intersection of the surface of the plastic lens 30 formed by the insert piece 12 and the insert piece 14 including the mirror surface portion 32 and the rib 31 of the plastic lens 30 formed by the insert piece 11 and the insert piece 12 and the insert piece 14. The concave portion 33 is provided in the mirror portion 32 which is a transfer surface.
Are formed selectively in the thick portion corresponding to the intersection of the surface including the rib 31 and the rib 31.

After that, the plastic lens 30 is molded by the usual injection molding procedure. By the formation of the plastic lens 30, sink marks can be selectively guided to the concave portion 33 formed in the thick portion corresponding to the intersection between the portion to be the mirror portion 32, which is the non-transfer surface, and the portion to be the rib 31. Thus, the distortion in the mirror surface portion 32 can be effectively reduced.

As shown in FIG. 3, the plastic lens 30 molded as described above is
3 is formed, and the portion where the concave portion 33 is formed is a non-transfer surface other than the mirror surface portion 32 which is the transfer surface of the insert piece 12 and the insert piece 14, so that the distortion of the mirror surface portion 32 is reduced. be able to.

Therefore, the rib 3 is long and thin.
1 can be formed with low distortion and high shape accuracy. In particular, the mirror portion 32
Can be formed with high shape accuracy.

Further, since the concave portion 33 is formed in the thick portion corresponding to the intersection between the surface including the mirror surface portion 32 and the rib 31,
The distortion of the mirror portion 32 can be further reduced.

In the above case, at the time of molding the plastic lens 30, the rib 31, particularly, the plastic lens 30
The surface including the surface to be the mirror surface portion 32 and the plastic lens 3
In the thick part corresponding to the intersection with the part to be the rib 31 of 0,
As shown in FIG. 4, two or more recesses 33 are formed in the ribs 31 of the molded plastic lens 30, or two or more recesses 33 are formed. It may be.

In this way, the distortion of the entire area of the molded plastic lens 30 can be reduced.

As described above, as the resin 20 used for molding, when the molded product is an optical element requiring transparency such as the plastic lens 30 or the like,
Amorphous resin whose softening temperature is the glass transition temperature, for example, polymethacrylic resin, polycarbonate resin, alicyclic acrylic resin, cyclic polyolefin copolymer (specific examples, ZEONEX (trade name) manufactured by Zeon Corporation), etc. When a molded article is not required to have transparency such as an optical element, a crystalline resin having a softening temperature equal to its melting temperature can be used.

Although the invention made by the inventor has been specifically described based on the preferred embodiments, the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the gist of the invention. It goes without saying that it is possible.

For example, in the above-described embodiment, as a method for selectively inducing sink marks on the non-transfer surface, the concave portion 21 is formed in the resin 20 in the cavity 15 and the concave portion 33 is formed in the molded plastic lens 30. Although it is formed and the distortion is reduced, a convex portion may be formed on the molded product by forming a convex portion on the resin in the cavity.

In this case, the resin pressure is locally released to the cavity wall surface facing the portion where the convex portion is formed during the molding process, that is, by locally releasing the resin pressure, the convex portion in the cavity is released. Is formed to form a convex portion on the molded product.

Further, in the above embodiment, as the plastic molded product, the transfer surface is a curved surface, that is, the mirror surface 3.
The case where the transfer surface is 2 has been described, but the transfer surface is not limited to a curved surface. For example, as shown in FIG. 5, the transfer surface 41 of the plastic molded product 40 may have a planar shape. . In FIG. 5, reference numeral 42 denotes a rib.

Furthermore, in the above-described embodiment, the case where the transfer surface of the plastic molded product, that is, the two mirror surfaces 32 is shown, has been described. However, as shown in FIG. The surface 51 may be only one surface. In FIG. 6, reference numeral 52 denotes a rib.

[0060]

According to the first aspect of the present invention, the one or more ribs formed around the one or more transfer surfaces on which the transfer surfaces of the mold cavities are transferred are provided. At any position of at least one rib, a concave portion or a convex portion, or an incompletely transferred portion of both the concave portion and the convex portion, which is formed by incomplete transfer of the opposite mold cavity shape at the time of molding processing is formed. Since it is possible to selectively induce the sink of plastic resin in the incomplete transfer area, even a long, thin-walled plastic molded product has a low distortion and high shape precision transfer surface. Can be secured.

According to the second aspect of the present invention, since the incomplete transfer portion is formed at the intersection of the rib including the transfer surface and the rib, the incomplete transfer portion is formed at the intersection of the rib including the transfer surface. The sink of the transfer surface can be appropriately guided to the incomplete transfer portion, so that the distortion on the transfer surface can be further reduced, and the shape accuracy of the transfer surface can be further improved.

According to the third aspect of the invention, since the incompletely transferred portion is formed at two or more positions on one surface of the rib, the incompletely transferred portion is more efficiently shrunk. As a result, the distortion of the entire plastic molded product can be further reduced, and the shape accuracy of the transfer surface can be further improved.

According to the fourth aspect of the present invention, since the plastic molded article is formed by the injection molding method or the injection compression molding method, the plastic molded article can be inexpensively and effectively formed on the incomplete transfer portion. The sink can be induced, the distortion can be further reduced, and the shape accuracy of the transfer surface can be further improved.

According to the fifth aspect of the present invention, since the incompletely transferred portion is formed as a concave portion formed by local mold shrinkage with respect to the shape of the mold cavity facing during molding. It is possible to inexpensively and effectively induce sink marks in the incomplete transfer portion, to further reduce the distortion, and to further improve the shape accuracy of the transfer surface.

According to the sixth aspect of the present invention, since the incompletely transferred portion is formed as a convex portion formed by locally releasing the resin pressure with respect to the shape of the mold cavity facing the molding process. In addition, it is possible to inexpensively and effectively induce sink marks in the incomplete transfer portion, further reduce the distortion, and further improve the shape accuracy of the transfer surface.

According to the seventh aspect of the present invention, since the plastic molded product is a plastic optical element having at least one of the transfer surfaces being an optical mirror surface, the transfer surface has a sink mark in the incomplete transfer portion. Guide properly,
Distortion on the transfer surface that becomes the optical mirror surface can be reduced,
The plastic optical element can have an optical mirror surface with high shape accuracy.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a main part of a molding die for molding a plastic molded product to which an embodiment of the plastic molded product of the present invention is applied.

FIG. 2 is a front sectional view of a plastic lens molded by the molding die of FIG. 1;

FIG. 3 is a side sectional view of the plastic lens of FIG. 2;

FIG. 4 is a side sectional view of a plastic lens in which concave portions are formed at two places.

FIG. 5 is a side sectional view of a plastic molded product having a flat transfer surface.

FIG. 6 is a side sectional view of a plastic molded product having only one transfer surface.

FIG. 7 is a front sectional view of a conventional plastic lens.

FIG. 8 is a side sectional view of the conventional plastic lens of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Molding die 11-14 Insertion piece 15 Cavity 16 Vent hole 17 Vent passage 18 Vent tube 19 Gas supply source 20 Resin 30 Plastic lens 31 Rib 32 Mirror surface part 33 Concave part

Claims (7)

[Claims] 1. One or more transfer surfaces on which a transfer surface of a mold cavity is transferred by being filled and molded in a mold cavity, and one or more transfer surfaces formed on a peripheral portion of the transfer surface. And a plastic molded product having at least one of the ribs formed at an arbitrary position on the at least one of the ribs by incomplete transfer of the shape of a mold cavity facing the mold at the time of molding using the mold cavity. Recess, or
A plastic molded product having a convex portion or an incompletely transferred portion of both a concave portion and a convex portion. 2. The plastic molded article according to claim 1, wherein said incomplete transfer portion is formed at an intersection of said rib and a surface including said transfer surface. 3. The plastic molded product according to claim 1, wherein the incomplete transfer portion is formed at two or more positions on one surface of the rib. 4. The plastic molded article according to claim 1, wherein said plastic molded article is formed by an injection molding method or an injection compression molding method. 5. The method according to claim 1, wherein the incomplete transfer portion is a concave portion formed by local mold shrinkage with respect to the shape of the mold cavity facing the molding process. 5. The plastic molded article according to any one of 4. 6. The method according to claim 1, wherein the incomplete transfer portion is a convex portion formed by locally releasing resin pressure with respect to the shape of the mold cavity facing the molding process. Item 6. A plastic molded article according to any one of Items 4. 7. The plastic molded product according to claim 1, wherein the plastic molded product is a plastic optical element in which at least one of the transfer surfaces is an optical mirror surface.