JPH1095047A - Resin matrix shape and molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain especially highly precise optical parts in long and large sized molded products in a short molding cycle by a method wherein a shape of resin matrix to be preworked in advance by injection molding is optimized, and the resin matrix is used. SOLUTION: A plastic molded product is manufactured by transferring a mirror surface with resin inner pressure following melt of resin by containing a process wherein resin matrix preworked in advance in an almost final shape by injection molding is charged into a cavity of a mold having at least one mirror surface, and slowly cooled to heat distorsion temperature of the resin or under. When a length in a vertical direction to a surface to which the mirror surface of the resin matrix 2 is transferred in h", and a length of the molded product 1 in a vertical direction to a surface to which the mirror surface is transferred by charging into the cavity of the mold having the mirror surface is h, fluctuation according to a place of h"/h is within 0.03. Thereby, pressure generated in a vertical direction to the transferred surface after charging into the mold having the transferred surface and raising temperature, becomes uniform, and the molded product of the highly precise transferred surface can be obtained in a short molding cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin base material shape, a molding die, and a molding method, and more particularly, to a lens,
The present invention relates to a technique for manufacturing a high-precision plastic molded product such as a mirror and a prism, and can be applied to optical components of an optical scanning system such as a copying machine, a facsimile, a laser beam printer, and an optical device such as a camera.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open No. 4-16 / 1990 discloses a manufacturing method for obtaining high-precision plastic molded products such as lenses and mirrors.
There is 3119 gazette (a method for producing a plastic molded product). The method of molding a plastic molded product described in Japanese Patent Application Laid-Open No. 4-163119 has a resin base material pre-processed into a substantially final shape of a resin product by injection molding and having at least one or more transfer surfaces. After being charged into the mold cavity and heated above the glass transition temperature of the resin,
This is a method for producing a resin molded product that includes a step of gradually cooling the resin to a temperature equal to or lower than a thermal deformation temperature of the resin and that transfers a transfer surface of a cavity by an internal pressure of the resin accompanying melting of the resin.

[0003] The resin base material pre-processed to almost the final shape by injection molding includes internal strain, residual stress, dimensional differences, sink marks generated during cooling and solidification (particularly when the molded product is long or large). )
There is. According to the invention described in the above publication, in order to eliminate the non-uniformity of the resin base material, the resin base material is charged into a mold cavity having a transfer surface to obtain a high-precision plastic molded product.

[0004] In this way, the resin base material pre-processed to almost the final shape by injection molding ideally has the same shape as the molded product after the transfer surface is transferred by the internal pressure of the resin due to the melting of the resin. It has a close shape (however, it is not necessary that the transcription is mirror-finished). This improves the accuracy of the molded product obtained after the step of transferring to the transfer surface, and
The molding cycle can be shortened.

[0005] However, in the case of obtaining a long and large molded product by the above-mentioned method for producing a plastic molded product, it is necessary to obtain a resin base material having a shape close to that of the molded product after transferring the transfer surface of the mold cavity. Is difficult. This is because, in the case of a long and large molded product, the above-described internal strain, residual stress, and dimensional difference easily occur in the resin base material. Due to this, the required molded product precision (shape,
Even if the internal strain cannot be obtained or the precision of the molded product can be obtained, the molding cycle becomes long.

As a method of solving the above problem, there is Japanese Patent Application No. 8-30256 (the shape and molding method of the resin base material) previously submitted by the present applicant. This describes the shape of a resin base material and a molding method for molding a long and large molded product with high precision and a short molding cycle in order to solve the above-mentioned problem.

However, the applicants have continued to study the relationship between the shape of the resin base material and the precision of the molded product, and have repeated experiments. As a result, for optical components such as lenses and mirrors,
In the shape of the resin base material, it has been found that the dimension in the direction perpendicular to the light transmitting surface or the light reflecting surface greatly affects the precision of the molded product.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to an injection molding method for obtaining long and large moldings, especially optical parts, with high precision and a short molding cycle. Accordingly, it is an object of the present invention to optimize the shape of the resin base material to be pre-processed and to manufacture an excellent molded product using the resin base material.

[0009]

According to a first aspect of the present invention, a resin base material pre-processed to a substantially final shape by injection molding is put into a cavity of a mold having at least one or more mirror surfaces. A method for producing a plastic molded product in which a mirror surface is transferred by the internal pressure of the resin accompanying the melting of the resin, the method including a step of gradually cooling the resin to a temperature not higher than the thermal deformation temperature of the resin; Assuming that the dimension in the direction is h ″ and the dimension in the direction perpendicular to the mirror-transferred surface after being introduced into the cavity of the mold having a mirror surface is h, the variation of the ratio h ″ / h depending on the location is 0.03. It is characterized by being within a mold having a transfer surface,
The pressure generated in the direction perpendicular to the transfer surface after the temperature is raised is made uniform so that a molded product with a highly accurate transfer surface can be obtained in a short molding cycle.

According to a second aspect of the present invention, a resin base material pre-processed to a substantially final shape by injection molding is charged into a cavity of a mold having at least one or more mirror surfaces, and a thermal deformation temperature of the resin is set. A method of producing a plastic molded product, wherein the mirror surface is transferred by the internal pressure of the resin accompanying the melting of the resin, wherein the dimension perpendicular to the mirror surface of the resin base material is defined as h ″. The dimension in each direction perpendicular to the vertical direction is b ″, m ″, the dimension perpendicular to the mirror-transferred surface after being inserted into the cavity of the mold having the mirror surface is h, and the dimension perpendicular to the vertical direction. Where b and m are the dimensions in each direction, the variation of the ratio h ″ / h depending on the location is within 0.03, and b> b ″ ≧ 0.9b (1) h> h ″ ≧ 0.9h (2) m _c > m ″> m (3) m _c : with transfer surface It is characterized by satisfying the following mold cavity dimensions, so that even if the shape of the resin base material varies, it is easy to put into a mold having a transfer surface and make the pressure generated in the direction perpendicular to the transfer surface uniform after heating. In addition, it is possible to obtain a molded product having a highly accurate transfer surface in a short molding cycle.

According to a third aspect of the present invention, in the first or second aspect of the invention, the adjustment of the amount of the resin base material charged into the cavity of the mold is performed at a portion other than the dimension perpendicular to the surface to be transferred to the mirror surface. With this feature, the processing accuracy of the resin base material molding die can be lowered, the cost of the die can be reduced, and a molded product with a high precision transfer surface can be obtained in a short molding cycle. It is something that can be done.

[0012] The invention of claim 4 is the invention of claim 1 or 2 or 3.
It is characterized by molding using the resin base material described in (1) above, so that the injection pressure in the direction perpendicular to the transfer surface after the injection of the mold having the transfer surface and the temperature rise is uniform, and the transfer surface is formed with high precision. The product is such that short moldings can be obtained in a cycle.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, referring to FIG.
No. 163119 (Method of manufacturing a plastic molded product)
The reason why it is difficult to obtain a high-precision molded product when a long, large-sized molded product is molded will be described below with reference to the drawings. FIG. 1A shows a plane mirror as an example of the molded article shape 1. This flat mirror is shown in FIG.
As shown in FIG. 1A, a reflection surface S is provided (I is a light transmission direction, R is a light reflection direction), and the surface S requires high shape accuracy.

FIG. 1B shows a resin base material 2 used at that time. As described in Japanese Patent Application No. 8-30256 (the shape of the resin base material and the molding method) previously proposed by the present applicant, the shape of the resin base material 2 is the final target dimension b, For h and m (FIG. 1A), b ″, h ″,
By satisfying the following expressions (1) to (3) with m ″ (FIG. 1B), it is possible to increase the precision of the molded product and shorten the molding cycle. b> b ″ ≧ 0 .9b (1) h> h ″ ≧ 0.9h (2) m _c > m ″> m (3) where h ″ is a dimension b ″ in a direction perpendicular to the surface of the resin member on which the mirror surface is to be transferred. m ″: dimension in each direction perpendicular to the h ″ direction h: dimension of the molded product in the direction perpendicular to the plane on which the resin base material is charged into the cavity having the mirror surface and the mirror surface is transferred b, m: h direction M _c : dimension of the mold cavity having the transfer surface at the temperature of the resin base material. However, as the required specifications of the molded product accuracy and the molding cycle become stricter, the above conditions are satisfied. Even now, it is no longer possible to satisfy the specifications.

Therefore, first, to find out the cause, FIG.
As shown in (1), the pressure was measured at three points (A, B, C) of the mirror surface of the resin base material 2 in the mold cavity 3. Then
After heating and cooling, it was found that pressure non-uniformity still remained depending on the location (FIG. 3 shows pressure changes at points A, B, and C). That is, it has been found that a high-precision molded product cannot be obtained unless the pressure is equalized in a direction perpendicular to the mirror surface (a surface requiring high precision). Conversely, where the required accuracy other than the mirror surface is low, it has been found that pressure equalization is not necessary as much as the mirror surface (when a resin base material is put into a mold having a transfer surface and heated, When the resin is in a liquid-like state, the generated pressure is not anisotropic, but in the case of resin, the generated pressure is anisotropic because it is close to a solid).

Therefore, in order to equalize the pressure, FIG.
The dimension of h ″ of the resin base material 2 shown in (B) is very important. According to the experiments conducted by the present applicant, the dimension of the resin base material 2 in the direction perpendicular to the mirror surface of the resin base material 2 is h. "When the dimension in the direction perpendicular to the surface on which the mirror surface is transferred by being put into the cavity having the mirror surface is assumed to be h, the variation of the ratio h" / h depending on the location must be within 0.03. I understood.

FIG. 4 shows a distribution of pressure generated when the resin base material 2 is put into a mold 3 having a transfer surface by using the resin base material 2 and heated. As compared with the case of FIG. 3, the unevenness of the generated pressure was reduced, and the precision of the molded product and the molding cycle were improved.

Although the example shown in FIG. 1 is a plane mirror having a simple shape, it can be applied to a complicated shape as shown in FIG. 5 (FIG. 5A shows the shape of the molded product 4, FIG. B) shows the shape of the resin base material 5). That is, h ″ (x) / h
By setting the variation due to the location (x) within 0.03, a highly accurate molded product can be obtained in a short molding cycle. At this time, by satisfying the above-mentioned expressions (1) to (3), pressure uniformization is further promoted.

FIG. 6 shows a resin base material 6 which is a cylindrical lens.
In this case, the fluctuation of m ″ / m needs to be within 0.03 in order to equalize the pressure in a direction perpendicular to the direction (I direction) through which light is transmitted.

FIG. 7 shows the shape of a resin base material 7 which is a lens having an uneven thickness used in an optical scanning system or the like. In this case as well, the shape is perpendicular to the direction in which light is transmitted (I direction). In order to make the pressure uniform, the fluctuation of b ″ / b needs to be within 0.03.

In the case of a flat mirror having a simple shape as shown in FIG. 1, the processing accuracy of the mold can be improved.
Although it is possible to make the variation of h ″ / h 0.03 or less, in the case of a complicated shape as shown in FIG. 5, h ″ (x)
It may be difficult to make the fluctuation of / h (x) 0.03 or less. In that case, as shown in FIG.
(= Mold cavity shape) is provided with a generated internal pressure adjusting portion 9 in a portion other than the direction perpendicular to the light transmitting surface, and the generated internal pressure in the direction perpendicular to the light transmitting surface is adjusted to be uniform. In other words, the size of the resin base material that is sensitive to the internal pressure generated in the direction perpendicular to the light transmitting surface is adjusted so that the internal pressure generated in the direction perpendicular to the surface perpendicular to the transmitting surface is uniform in other insensitive portions. Thereby, the processing accuracy required for the mold can be reduced.

[0022]

According to the first aspect of the present invention, at least one resin base material pre-processed to a substantially final shape by injection molding is used.
Including in the mold cavity having two or more mirror surfaces and slowly cooling to a temperature below the heat deformation temperature of the resin,
In a method of manufacturing a plastic molded product in which a mirror surface is transferred by the internal pressure of the resin caused by melting of the resin, a dimension perpendicular to the surface of the resin base material to which the mirror surface is transferred is h ″, and the resin base material is charged into a cavity of a mold having the mirror surface When the dimension in the direction perpendicular to the mirror-transferred surface is h, the variation of the ratio h ″ / h depending on the location is within 0.03. Therefore, the resin base material is put into a mold having a transfer surface. After the temperature rise, the pressure generated in the direction perpendicular to the transfer surface of the resin base material becomes uniform, and a molded product with a highly accurate transfer surface can be obtained in a short molding cycle.

According to a second aspect of the present invention, a resin base material pre-processed into a substantially final shape by injection molding is put into a cavity of a mold having at least one or more mirror surfaces, and a thermal deformation temperature of the resin is set. A method for producing a plastic molded product in which a mirror surface is transferred by the internal pressure of the resin accompanying the melting of the resin, wherein the dimension in the direction perpendicular to the mirror surface of the resin base material is set to h ″ The dimension in each direction perpendicular to the vertical direction is b ", m", the dimension perpendicular to the mirror-transferred surface which is charged into the cavity of the mold having a mirror surface is h, and the dimension perpendicular to the vertical direction is h. Where b and m are the dimensions in each direction, the variation of the ratio h ″ / h depending on the location is within 0.03, and b> b ″ ≧ 0.9b (1) h> h ″ ≧ 0.9h (2) m _c > m ″> m (3) m _c : with transfer surface Mold cavity dimensions to be filled, so that even if the shape of the resin base material varies, the pressure generated in the mold with the transfer surface and in the direction perpendicular to the transfer surface after the temperature rises can be more uniform. In addition, a molded product having a highly accurate transfer surface can be obtained in a short molding cycle.

According to a third aspect of the present invention, in the first or second aspect, the adjustment of the amount of the resin base material put into the cavity of the mold is performed in a portion other than the dimension perpendicular to the surface to be transferred to the mirror surface. As a result, it is possible to reduce the processing accuracy of the resin base material molding die, to reduce the cost of the die, and to obtain a molded product with a highly accurate transfer surface in a short molding cycle. Can be.

The invention of claim 4 is the invention of claim 1 or 2 or 3
Since the molding using the resin base material described in the above, the pressure in the direction perpendicular to the transfer surface after the injection of the mold having the transfer surface and the temperature rise becomes uniform, and the molded product having the transfer surface with high precision can be shortened. Molded articles can be obtained in cycles.

[Brief description of the drawings]

FIG. 1 is a plane mirror as an example of a molded product shape (FIG. 1)
FIG. 1A is a perspective view showing an example of a resin base material (FIG. 1B) used for forming the flat mirror.

FIG. 2 is a perspective view showing an example of measuring pressure unevenness of a resin base material in a mold cavity.

FIG. 3 is a diagram showing a pressure distribution (conventional) in a mold cavity.

FIG. 4 is a diagram showing a pressure distribution in the mold cavity (the present invention).

FIG. 5 is a perspective view showing an example of a molded article having a complicated shape (FIG. 5A) and a resin base material (FIG. 5B) used for forming the molded article.

FIG. 6 is a perspective view showing an example of a resin base material used for forming a cylindrical lens.

FIG. 7 is a perspective view showing an example of a resin base material used for forming an uneven thickness lens.

FIG. 8 is a perspective view showing an example for adjusting the generated internal pressure.

[Explanation of symbols]

1,4 ... molded product shape, 2,5,6,7 ... resin base material shape,
Reference numeral 3 denotes a mold, 8 denotes a molded product (or a resin base material), 9 denotes a generated internal pressure adjusting unit.

Claims (4)

[Claims] 1. A resin base material pre-processed to a substantially final shape by injection molding is put into a cavity of a mold having at least one or more mirror surfaces and gradually cooled to a temperature equal to or lower than a heat deformation temperature of the resin. A method for producing a plastic molded product, comprising a step of cooling and transferring a mirror surface by the internal pressure of the resin caused by melting of the resin, wherein a dimension in a direction perpendicular to the surface of the resin base material to which the mirror surface is transferred is h ″, Assuming that the dimension in the direction perpendicular to the mirror-transferred surface after being put into the cavity of the mold is h, the variation of the ratio h ″ / h depending on the location is 0.
A resin base material shape characterized by being within 03. 2. A resin base material pre-processed to a substantially final shape by injection molding is introduced into a cavity of a mold having at least one or more mirror surfaces, and gradually cooled to a temperature equal to or lower than a heat deformation temperature of the resin. A method of manufacturing a plastic molded product that includes a step of cooling and transfers a mirror surface by the internal pressure of the resin accompanying the melting of the resin, wherein the dimension of the resin base material in the direction perpendicular to the surface to which the mirror surface is transferred is h ″, The dimensions in each of the perpendicular directions are b ″ and m ″, the dimension in the direction perpendicular to the mirror-transferred surface which is charged into the cavity of the mold having a mirror surface is h, and the dimension in each direction perpendicular to the perpendicular direction. To b and m,
The variation of the ratio h ″ / h depending on the location is within 0.03, and b> b ″ ≧ 0.9b (1) h> h ″ ≧ 0.9h (2) m _c > m ″ > M ... (3) _mc : a resin base material shape characterized by satisfying a mold cavity size having a transfer surface. 3. The resin according to claim 1, wherein the amount of the resin base material charged into the cavity of the mold is adjusted in a portion other than a dimension perpendicular to a surface to be transferred to a mirror surface. Base material shape. 4. A method for molding a molded article, comprising molding using the resin base material according to claim 1, 2 or 3.