JP2716333B2 - Manufacturing method of plastic molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a plastic molded product applied to an optical scanning system such as a laser beam printer and a facsimile, a video camera and the like. The present invention relates to a method for producing a plastic molded article suitable for producing a molded article.

[0002]

2. Description of the Related Art As a conventional method for producing a plastic molded product of this type, a resin is heated to a temperature higher than a flowable temperature of the resin and injected into a mold maintained at a temperature lower than a heat deformation temperature of the resin. Injection molding process to pre-process to a substantially final shape
The pre-processed resin base material was put into a cavity of an aging mold, kept at a temperature higher than the glass transition temperature of the resin for a predetermined time, and then gradually cooled to a temperature lower than the heat deformation temperature of the resin. An aging process and an aging process are known (JP-A-4-163119).

In this method, since the injection step and the aging step are divided, the injection molding step and the aging step can be designed to be suitable for molding, and the number of molds to be taken in the aging step can be reduced. There is an advantage that a large number of agings can be performed with one aging mold by setting the number of dies larger than the number of molds to be taken in the injection molding.

[0004]

However, in the method of manufacturing a plastic molded product by dividing the process into an injection molding process and an aging process, a large-sized injection molding process is required to obtain a large and long molded product. I needed a machine. That is, in the injection step, a large resin pressure is generated when the molten resin is injected and filled into the mold, so that a large clamping force is required, and the mold is formed in order to form a large and long molded product. A large injection molding machine with a large tightening force is required. On the other hand, in the aging step, only the internal pressure is generated due to the thermal expansion of the resin due to the temperature rise of the aging mold, so that the mold clamping force may be small. Therefore, a large-sized molding machine is required to produce a large-sized and long molded product despite the fact that a large-sized aging mold is not required, and the production cost is greatly increased. there were.

Further, since the cavities of the injection mold and the aging mold have the same shape in order to form the same molded product, only one type of molded product can be manufactured. There is a problem that the same mold cannot sufficiently cope with mass production of varieties. In view of the above, the invention according to claim 1 divides a resin base material pre-processed into a substantially final shape by injection molding into two or more parts, that is, makes it possible to mold the resin base material into two or more times, so that individual injection molding can be performed. It is an object of the present invention to provide a method for manufacturing a low-cost plastic molded product, which can reduce the clamping force of the molded product and can easily produce a large and long molded product by a small molding machine.

The invention according to claim 2 provides a mold clamping force at the time of injection molding by making the dividing direction of the resin base material pre-processed into a substantially final shape not parallel to the parting surface of the aging mold. It is an object of the present invention to provide a method for producing a plastic molded article, which can further reduce the size of the molded article. According to a third aspect of the present invention, there is provided a method of manufacturing a plastic molded article which can be easily formed into an uneven thickness by bonding a resin base material, and in which a sink in the molded article can be prevented. It is intended to provide.

It is an object of the present invention to provide a method of manufacturing a plastic molded article capable of manufacturing molded articles of various shapes by manufacturing molded articles of a predetermined shape. The invention according to claim 5 prevents bubbles from being mixed into the central portion of the joining surface of the resin base material during the aging step, and air bubbles from being mixed into the central portion of the molded article in which the resin base material is integrated. It is an object of the present invention to provide a method for producing a high-quality plastic molded product, which can prevent the occurrence of a plastic molding.

According to a sixth aspect of the present invention, the inside of the cavity of the aging mold is evacuated during the aging step, thereby preventing air bubbles from being mixed into the central portion of the joining surface of the resin base material during the aging step. It is another object of the present invention to provide a method for manufacturing a high-quality plastic mold, which can prevent air bubbles from being mixed into a central portion of a molded product in which the resin base material is integrated.

[0009]

According to the first aspect of the present invention,
In order to solve the above-mentioned problem, a resin base material pre-processed to a substantially final shape by injection molding is put into a cavity of an aging mold having at least one or more mirror surfaces, and the glass transition temperature of the resin or more is set. After holding for a predetermined time with,
An aging step of gradually cooling the resin to a temperature equal to or lower than the thermal deformation temperature of the resin, wherein the method for manufacturing a plastic molded product in which a mirror surface is transferred by a resin internal pressure accompanying the melting of the resin, By introducing at least two or more resin base materials pre-processed by injection molding into the cavity and performing aging,
It is characterized in that one or more resin base materials are melt-bonded to produce an integral molded product.

According to a second aspect of the present invention, in order to solve the above-mentioned problems, the joining surface of the two or more resin base materials is set in a direction not parallel to the parting surface of the aging mold. It is characterized in that the base material is melt-bonded in the cavity. According to a third aspect of the present invention, in order to solve the above-mentioned problem, a resin base material having a uniform thickness by the injection molding is used.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problems, a molded article having a predetermined shape is manufactured by allowing each of the two or more resin base materials to be freely replaced at a predetermined position in a cavity. It is characterized by doing so. According to a fifth aspect of the present invention, in order to solve the above-described problems, the opposing joining surfaces of the two or more resin base materials are formed into a convex shape by injection molding in advance, and then the convex portions are joined. It is characterized in that it is put into the cavity of the aging mold.

In order to solve the above-mentioned problem, the invention according to claim 6 is characterized in that the inside of the cavity of the aging mold is evacuated during the aging step.

[0013]

According to the first aspect of the present invention, at least two or more resin base materials pre-processed by injection molding are charged into the same cavity of the aging mold, and aging is performed. The resin base material is melt-bonded to produce an integral molded product.

Therefore, the resin base material pre-processed to a substantially final shape by injection molding can be divided into two or more, that is, it can be molded in two or more times, and the clamping force at the time of individual injection molding is reduced. Become smaller. For this reason, a large and long molded product can be easily produced by a small molding machine, and the production cost of the molded product can be reduced. Further, when the molded product has a complicated shape, the base material in the injection step is hardly injected into an aging mold due to thermal shrinkage. Therefore, by dividing the base material, the base material is easily put into the aging mold.

According to the second aspect of the present invention, the resin base materials are bonded in the cavity such that the bonding surface of the two or more resin base materials is in a direction not parallel to the parting surface of the aging mold. . Therefore, the direction of division of the resin base material pre-processed into the substantially final shape and the direction of clamping of the aging mold coincide, and the clamping force during injection molding is further reduced. According to the third aspect of the present invention, a resin base material having a uniform thickness by injection molding is used. Therefore, the resin base material is joined to easily form an uneven thickness, and at this time, sinkage does not occur in the molded product.

According to the fourth aspect of the present invention, two or more resin base materials are respectively replaced at predetermined positions in the cavity, and a molded article having a predetermined shape is manufactured. Therefore, molded articles of various shapes are manufactured. According to the fifth aspect of the present invention, the opposing joining surfaces of two or more resin base materials are formed into a convex shape by injection molding in advance, and then the convex portions are joined and put into the cavity of the aging mold. Is done.
Therefore, it is possible to prevent air bubbles from being mixed into the central portion of the joining surface of the resin base material during the aging step. That is, if the joining surface of the resin base material put into the cavity of the aging mold is flat, air bubbles are likely to be mixed into the center of the joining surface. For this reason, by forming this portion into a convex shape, air bubbles are not mixed into the central portion of the molded product in which the resin base material is integrated, and the quality of the molded product is improved.

According to the sixth aspect of the present invention, the inside of the cavity of the aging mold is evacuated during the aging step. Therefore, during the aging process, no air bubbles enter the central portion of the joining surface of the resin base material, and no air bubbles enter the central portion of the molded article in which the resin base material is integrated. As a result, the quality of the molded product is improved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
1 to 4 are views showing one embodiment of a method for producing a plastic molded product according to the first aspect of the present invention. The feature of this embodiment is that when a large lens or the like is manufactured as shown in FIG. 1A, a large clamping force is required at the injection / filling step. Two small resin base materials are pre-processed in advance by injection molding, and this 2
The point is that two resin base materials are joined.

First, the configuration will be described. FIG. 2 is a diagram showing an injection molding machine for achieving the present embodiment. In FIG. 1, reference numeral 1 denotes an injection molding machine. The injection molding machine 1 has a fixed platen 2 and a movable platen 3. 5
And movable molds 6 and 7 are attached. These dies 4 to 7 are set so that the temperature of the cavity 8 is equal to or lower than the heat deformation temperature of the resin.
11 is to be injected and filled.

After injection and filling, the gate portion of the sprue runner 10 is cooled and solidified, and when the resin temperature is completely reduced to the heat deformation temperature or less, the fixed molds 4, 5 and the movable mold are moved. 6 and 7, the resin base material 12 pre-processed into a substantially final shape is taken out as shown in FIG. 1 (b). On the other hand, in FIG. 3, reference numeral 13 denotes an aging mold, and the mold 13 has cavities 14 on contact surfaces facing each other.
An upper mold 15 and a lower mold 16 are provided.

Next, the operation will be described. First, two resin base materials 12 pre-processed into a substantially final shape by the injection molding machine 1 are formed in two parts. Next, the resin base material 12 is layered and placed in the same cavity 14 of the aging mold 13, and is kept at a temperature higher than the glass transition temperature of the resin for a predetermined time, and then gradually lowered to a temperature lower than the thermal deformation temperature of the resin. Let cool. As a result, the two resin base materials 12 are melt-bonded, and an integral molded product 17 is manufactured as shown in FIG.

As described above, in this embodiment, the aging mold
Injecting two resin base materials 12 pre-processed by injection molding into the same cavity 14 of 13 and performing aging, the two resin base materials 12 are melt-bonded to form an integral molded product 17. Since the resin base material 12 is manufactured, the resin base material 12 that has been pre-processed to a substantially final shape by injection molding can be divided into two or more, that is, molded in two steps. For this reason,
The mold clamping force during individual injection molding can be reduced,
A large and long molded product can be easily produced by the small molding machine 1, and the production cost of the molded product can be reduced.

In this embodiment, two resin base materials 12 are aged, but it goes without saying that two or more resin base materials may be used as shown in FIG. That is, as shown in FIG. 4A, a base material having a complicated shape having ribs on both sides in a cavity 18 is provided.
When the base material 19 is injected, the base material 19 may not be injected into the cavity 18 due to heat shrinkage during the injection process.
As shown in (a), the base material is made of ribs 20a and 20c and the main body 20b.
If it is divided into three, it can be easily put into the cavity 18.

FIGS. 5 to 7 show one embodiment of the method for producing a plastic molded product according to the second aspect of the present invention. In FIG. 5, reference numeral 24 denotes an aging mold including an upper mold 22 and a lower mold 23 in which cavities 21 are formed on surfaces facing each other. In the cavity 21 of the mold 24, two resin base materials 25 are formed. The resin base material 25 is joined in the cavity 21 so that the joining surface is in a direction not parallel to the parting surface of the mold 24, that is, in the same direction as the mold clamping direction (the direction of the arrow). Is performed.

By doing so, it is possible to make the direction of division of the resin base material 25 pre-processed into the substantially final shape coincide with the direction of clamping of the aging mold 24, thereby further reducing the clamping force during injection molding. Can be smaller. When such a method is applied, as shown in FIG. 6, a plurality of resin base materials 26 are solid-formed by injection molding, and a plurality of resin base materials 26 are solid-joined and aged, thereby easily manufacturing a lens group. be able to.

When a molded article having a complicated shape is manufactured, the resin base materials 27a to 27c are divided into a plurality of pieces so as to be in the same direction as the mold clamping direction of the mold 24 as shown in FIG. By doing so, the resin base materials 27a to 27c can be easily inserted into the cavity 21. Further, if a base material having a complicated shape is formed in the injection step, a density distribution is likely to occur. Even if the base material having such a density distribution is aged, the density can be made uniform to some extent, but there is a limit. Therefore, if the base material is divided and the density is made uniform and aged as in this embodiment, a final shape having a uniform density distribution can be obtained. In addition, it is possible to prevent resin filling failure during the injection process of a complicated shape.

FIG. 8 is a view showing one embodiment of the method for manufacturing a plastic molded product according to the third aspect of the present invention. In FIG. 8, reference numeral 34 denotes an aging mold including an upper mold 32 and a lower mold 33 in which cavities 31 are formed on surfaces facing each other,
In the cavity 31 of the mold 34, a plurality of resin base materials 35a to 35d each having a uniform thickness formed by injection molding are put. In this embodiment, by manufacturing in this manner, a molded product having an uneven thickness, in which sink marks tend to occur, can be easily manufactured without sink marks.

In order to obtain a formed product 38 having a large area as shown in FIG. 9A, if the base materials 38a to 38d are divided and formed as shown in FIG. By changing the mold clamping direction when forming a product in the injection step and the mold clamping force when aging this molded product, the cross-sectional area of the molded product can be reduced as shown in FIG. The mold clamping force of the mold can be reduced. Therefore, a large number of base materials 39a to 39d can be taken out as shown in FIG.

FIGS. 10 (a) and 10 (b) are views showing one embodiment of the method for producing a plastic molded product according to the fourth aspect of the present invention. In FIG. 10A, reference numeral 44 denotes an aging mold including an upper mold 42 and a lower mold 43 in each of which a cavity 41 is formed on a surface facing each other. In the cavity 41 of the mold 44, a plurality of resin mothers are provided. Materials 45a to 45c have been loaded.

On the other hand, the aging mold 41 shown in FIG. 10B is configured such that the shape of the cavity 46 is different from that of the cavity 41 described above.
Specifically, the portion where the resin base material 45c is inserted is formed to be wider and shallower than the corresponding portion of the cavity 41. That is, in this embodiment, three resin base materials 45 are used.
a to 45c are freely replaceable at predetermined positions in the cavities 41 and 46, respectively.
A variety of molded products are manufactured by changing the input positions of the resin base materials 45a to 45c according to the shape.

FIG. 11 is a view showing one embodiment of the method for producing a plastic molded product according to the fifth and sixth aspects of the present invention. Figure
In 11, 54 is an aging mold composed of an upper mold 52 and a lower mold 53 in which cavities 51 are formed on surfaces facing each other. Pre-processed resin base material 55a, 55b
Are introduced.

The resin base materials 55a and 55b are formed in advance so that the opposing joint surfaces are formed into a convex shape by injection molding.
It is thrown into. Therefore, it is possible to prevent air bubbles from being mixed into the central portion of the joint surface between the resin base materials 55a and 55b during the aging process. That is, if the joining surface of the resin base materials 55a and 55b charged into the cavity 51 of the aging mold 54 is a flat surface, air bubbles are easily mixed into the central portion of the joining surface, so that this portion has a convex shape. Thereby, it is possible to prevent air bubbles from being mixed into the central portion of the molded article in which the resin base materials 55a and 55b are integrated, and to improve the quality of the molded article.

In addition to this, if the inside of the cavity 51 of the aging mold 54 is evacuated during the aging process, bubbles are mixed into the central portion of the joint surface between the resin base materials 55a and 55b during the aging process. Can be further prevented. The method of evacuating the cavity 51 as described above can be applied to one embodiment of the present invention.

[0034]

According to the first aspect of the present invention, the resin base material pre-processed into the substantially final shape by injection molding is divided into two or more, that is, it can be formed in two or more times. In addition, the mold clamping force at the time of individual injection molding can be reduced, and large and long molded products can be easily manufactured with a small molding machine. As a result, the manufacturing cost of the plastic molded product can be reduced.

According to the second aspect of the present invention, the mold clamping force at the time of injection molding is made by making the dividing direction of the resin base material pre-processed into a substantially final shape not parallel to the parting surface of the aging mold. Can be further reduced.
According to the third aspect of the present invention, it is possible to easily form the uneven thickness by joining the resin base materials, and it is possible to prevent the molded product from sinking at this time.

According to the fourth aspect of the present invention, it is possible to manufacture various types of molded products having different shapes. Claim 5,
According to the invention described in Item 6, bubbles are prevented from entering the central portion of the joining surface of the resin base material during the aging step, and the bubbles are introduced into the central portion of the molded article in which the resin base material is integrated. Thus, it is possible to provide a method for producing a high-quality plastic molded product.

[Brief description of the drawings]

FIG. 1 (a) is a configuration diagram of a molded article molded by an embodiment of the method for producing a plastic molded article according to the first aspect of the present invention, and FIG. 1 (b) is divided by injection molding to obtain a substantially final shape. It is a block diagram of the processed resin base material.

FIG. 2 is a sectional view of the injection molding machine.

FIG. 3 is a sectional view of the aging mold.

FIG. 4A is a view showing a state in which a base material having a complicated shape is thermally shrunk and becomes difficult to be put into an aging mold, and FIG. 4B is a view showing a state where the base material is divided and put into an aging mold. FIG.

FIG. 5 is a sectional view of an aging mold for achieving one embodiment of the method for producing a plastic molded product according to the second aspect of the present invention.

FIG. 6 is a sectional view showing another embodiment of the aging mold.

FIG. 7 is a sectional view showing another embodiment of the aging mold.

FIG. 8 is a cross-sectional view of an aging mold for achieving one embodiment of the method of manufacturing a plastic molded product according to the third aspect of the present invention.

9A is a diagram showing a molded product having a large area, FIG. 9B is a diagram showing a molded product having a small cross-sectional area, and FIG. 9C is a diagram showing a base material molded in a large number in the injection step.

FIG. 10 is a cross-sectional view of an aging mold for achieving one embodiment of the method of manufacturing a plastic molded product according to the invention of claim 4.

FIG. 11 is a cross-sectional view of an aging mold for achieving one embodiment of the method of manufacturing a plastic molded product according to the fifth and sixth aspects of the present invention.

[Explanation of symbols]

12, 25, 26, 27a to 27c, 35a to 35d, 45a to 45c, 55
a, 55b Resin base material 13, 24, 34, 44, 54 Aging mold 14, 21, 31, 41, 46, 51 Cavity 17 Molded product

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Wataru Otani, 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Toshihiro Kanematsu 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Akihito Hirano 1-3-6 Nakamagome, Ota-ku, Tokyo Co., Ltd. Inside Ricoh Co., Ltd. (72) Shinya Senoo 1-3-6 Nakamagome, Ota-ku, Tokyo Co., Ltd. Inside Ricoh Company (72) Inventor Jun Watanabe 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (56) References JP-A-6-182783 (JP, A) JP-A-57-72821 (JP, A) JP-A-58-49219 (JP, A) JP-A-4-366608 (JP, A) JP-A-56-13139 (JP, A) JP-A-62-170732 (JP, U)

Claims (6)

(57) [Claims] 1. A resin base material pre-processed to a substantially final shape by injection molding is charged into a cavity of an aging mold having at least one or more mirror surfaces, and is kept at a temperature higher than a glass transition temperature of the resin for a predetermined time. An aging step of gradually cooling the resin to a temperature equal to or lower than the thermal deformation temperature of the resin, and transferring the mirror surface by the internal pressure of the resin accompanying the melting of the resin. Into the same cavity of the mold, at least two or more resin base materials pre-processed by injection molding are put and subjected to aging, thereby melting and joining two or more resin base materials to form an integrated molded product. A method for producing a plastic molded article, characterized in that it is produced. 2. The resin base material is melt-bonded in a cavity such that a bonding surface of the two or more resin base materials is not parallel to a parting surface of an aging mold. The method for producing a plastic molded product according to claim 1. 3. The method according to claim 1, wherein a resin base material having a uniform thickness by the injection molding is used. 4. The method according to claim 1, wherein the two or more resin base materials are freely interchangeable at predetermined positions in the cavity.
2. The method for manufacturing a plastic molded product according to claim 1, wherein the molded product has a predetermined shape. 5. The method according to claim 1, wherein the opposing joint surfaces of the two or more resin base materials are formed into a convex shape by injection molding in advance, and then the convex portions are joined and put into a cavity of an aging mold. The method for producing a plastic molded product according to claim 1, wherein: 6. The method for producing a plastic molded product according to claim 1, wherein the inside of the cavity of the aging mold is evacuated during the aging step.