JP2000280285A - Molded article with window part and its preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a molded article which has no inferiority of appearance such as defects and deformation and wherein a window part and the main body of the molded article are bonded by enough bonding strength without requiring a special installation, by an existing installation, by a convenient process and inexpensively. SOLUTION: A method for preparing a molded article with a window part comprises the steps of using a mold for injection molding consisting of a top mold 5a and a bottom mold 5b wherein recessed parts are formed in corresponding to the inner peripheral part of a window member, pinching only the outer peripheral part 3 of the window member 1 between the top mold 5a and the bottom mold 5b, holding the inner peripheral part of the window member in such a way that it is not brought into contact with the top mold 5a and the bottom mold 5b and filling a molten resin into a mold for injection molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded article having a window and a method for producing the same.

[0002]

2. Description of the Related Art Various molded products manufactured by injection molding have a window provided at a predetermined position. For example, magnetic tape cassettes such as DDS, DAT, DVC (Digital Video Cassette), VHS, and 8 mm video cassette tapes have both sides of a case for storing the magnetic tape so that the running state of the magnetic tape can be visually recognized from the outside. Alternatively, a window is provided on the upper surface.

For example, an upper half 91 of a digital video magnetic tape cassette (DVC) shown in a perspective view of FIG. 10 (a) shows a rewind state, a running state, and the like of a magnetic tape stored in the magnetic tape cassette. A window member 93 made of a transparent material is fitted to a predetermined portion of the upper half body 97 so that it can be visually recognized from the outside. This upper half 9
1, the perspective view of FIG. 10 (a) and FIG. 11 (b)
As shown in the sectional view of FIG.
5b, 95c and 95d are joined to the inner ends 99a, 99b, 99c and 99d of the window openings formed in the upper half body 97.

[0004] Also, in various devices such as a magnetic recording tape recorder and a camera, there are components provided with a window so that the inside state can be checked from outside and a predetermined display can be visually recognized. Further, the waterproof case 101 of the film unit with the lens shown in FIG. 13 stores the film unit 103 with the lens therein in a watertight state,
In order to take a picture with the film unit with lens 103, the camera has a release lever 105 for releasing the shutter from the outside, an operation dial 107 for winding the film, and the like. The waterproof case 101 includes a case main body 109 having an opening at the bottom and a bottom lid 111 fitted to the opening in a watertight manner in order to store the film unit with lens 103 in a watertight manner. The waterproof case 101 is provided with an exposure window 115 at a position corresponding to the photographing lens 113 so that an exposure light beam enters the photographing lens 113 of the film unit with lens 103 housed therein. ing. Also, windows are provided in portions corresponding to the viewfinder, the strobe, and the like.

As a method of manufacturing a molded article having these windows, a window member is conventionally fitted in an opening provided at a predetermined position of a molded article body, and the contact portions of the two are joined by ultrasonic welding. Using a mold having a movable part corresponding to the window part, performing two-stage injection molding, and manufacturing the molded product body and the window part simultaneously in the mold by two-color molding. Injection molding is performed by injecting a molten resin from a gate and filling the periphery of a window member arranged at a predetermined position in a mold to obtain a molded article in which the window member and the molded article body are integrally joined. Various methods such as methods are known.

[0006] In these methods, the method of joining by welding requires ultrasonic welding equipment. In addition, the method using two-color molding requires a special mold having a complicated structure and a molding machine. Therefore, these welding or two-color molding methods do not pose a problem in terms of cost when a large number of molded articles are produced, but are disadvantageous in terms of cost when a relatively small number of molded articles are produced. It is. On the contrary,
The method by insert molding does not require a special mold and equipment as compared with the method by welding or two-color molding, and is therefore suitable as a method for producing a relatively small amount of molded product.

In this insert molding method, for example, taking the manufacture of the upper half 91 of the magnetic tape cassette shown in FIG. 10A as an example, as shown in FIG.
After arranging the window member 119 at a predetermined position of the lower mold 117b of the injection molding mold, the upper mold 117a and the lower mold 117b sandwich the window member 119, and a gate (not shown). The molten resin is injected to fill the cavity.
The molten resin flows while wrapping around the window member 119 and joins on the opposite side to the gate to form a weld, thereby forming the upper half body. Next, the upper half 91 in which the upper half body and the window member are integrally joined can be obtained through the steps of pressure holding and cooling.

[0008]

However, according to the conventional insert molding method, the upper mold and the lower mold which hold the window member are in contact with the entire upper and lower surfaces of the window member. Due to surface scratches, foreign matter, etc.
The surface of the window member is scratched. Further, at the time of injection of the molten resin, the window member is pressed and rubbed with the mold due to the radiant power applied from the gate to cause abrasion, or in extreme cases, deform as shown in FIG. There was a problem. Scratches on the surface of the window, especially at the center, degrade the appearance of the molded product, and if the window is severely deformed, assembly and operation of other parts may be hindered. There may be problems with the production or function of the molded article.

[0009] Also, in other devices, scratches on the surface of the window or deformation of the window make it difficult to check the internal state and cause functional problems such as impairing the visibility of various displays. There was something. Further, in the waterproof case of the lens-equipped film unit shown in FIG. 13, if the window portion is damaged or deformed, normal exposure of the exposure light beam to the photographing lens of the lens-equipped film unit is hindered. Causes a problem such as impairing the photographic performance.

In addition, in insert molding, it is generally effective to reduce the injection pressure by increasing the resin temperature and the mold cooling water temperature in order to prevent deformation due to the injection force. A longer molding cycle is required, which reduces productivity.

Accordingly, an object of the present invention is to provide a molded article in which the window and the molded article main body are joined with sufficient joining strength without any appearance defects such as scratches and deformation without requiring special equipment. It is another object of the present invention to provide a method which can be manufactured at a low cost by a simple process using existing equipment and a molded product obtained by the manufacturing method.

[0012]

In order to achieve the above object, the present invention provides a method for injecting and filling a molten resin around a window member held at a predetermined position in an injection mold. A method for manufacturing a molded article having a window in which a window member and a molded article main body are integrally joined, wherein an upper mold and a lower part having a concave portion formed in correspondence with an inner peripheral portion of the window member. Using an injection mold composed of a mold, only the outer periphery of the window member is sandwiched between the upper mold and the lower mold so that the inner periphery of the window member does not contact the upper mold and the lower mold. It is intended to provide a method for producing a molded article having a window portion, wherein the molten resin is filled into an injection molding die while being held.

[0013] The present invention also provides a molded article having a window, which is manufactured by the above method.

Hereinafter, the method for producing a molded article having a window according to the present invention (hereinafter referred to as “method of the present invention”) and the molded article having a window according to the method will be described in detail.

According to the method of the present invention, there is provided a molded article having a structure in which a window member is fitted at a predetermined position of a molded article body, and an outer peripheral portion of the window member is integrally joined to a peripheral molded article body. This is a method of manufacturing by injection molding. The method of the present invention can be applied to the production of any molded article having a window. For example, DDS, DAT, DVC, VH
For manufacturing magnetic tape cassettes such as S, 8 mm video cassette tapes, various parts such as an upper half, an upper shell and a case provided with a window so that the running state of the magnetic tape can be visually recognized from the outside. Applicable. Further, the present invention can be applied to the manufacture of various components having a display window in various devices such as a magnetic recording tape recorder and a camera. Further, in a film unit with a waterproof lens, the present invention can be applied to the manufacture of a waterproof case in which a window is provided at a portion facing a photographic lens, a finder, a strobe, and the like.

[0016] The method of the present invention is an injection molding method comprising an upper mold and a lower mold having a concave portion corresponding to an inner peripheral portion of a window member integrally fitted to a predetermined portion of a molded article main body. After placing the window member at a predetermined position of the injection mold using the mold, the mold is closed and closed, and the upper mold, the lower mold, and the window member arranged inside A method for manufacturing a molded product in which a window member and a molded product main body are integrally joined at the same time as forming a molded product main body by injecting and filling a molten resin from a gate into a cavity formed between It is.

The injection molding die used in the method of the present invention holds the window member at a predetermined position between the upper die and the lower die when the die is clamped. The upper mold and the lower mold of the injection molding mold have concave portions formed corresponding to the inner peripheral portions of the upper surface and the lower surface of the window member arranged at a predetermined position, and when closing the window member, Only the outer periphery of the window member is held in contact with the surfaces of the upper mold and the lower mold, and the upper and lower surfaces of the inner periphery of the window member are held by the window member so as not to contact the upper mold and the lower mold. You. The window member has a fitting portion provided corresponding to a positioning portion provided in the mold, and is arranged at a predetermined position in the mold.

As described above, when the window member is held at a predetermined position and the molten resin is injected into the mold having the cavity corresponding to the molded article main body, the molten resin flowing from the gate flows through the window through the cavity. It flows around the window member along the outer periphery of the member, and merges on the opposite side of the gate to form a weld. At this time, the window member receives the injection pressure of the molten resin, and the outer peripheral portion is in contact with the upper mold or the lower mold. Since it is not in contact with the upper mold and the lower mold, scratches do not occur due to abrasion. In addition, the window member contacts the upper mold and the lower mold only at the outer periphery, and the inner periphery of the window member does not contact the upper mold and the lower mold. Spaces are formed between the upper surfaces and between the lower mold and the inner peripheral lower surface of the window member. Therefore, when there is a partially thick portion on the inner peripheral portion of the window member, for example, even if the central portion is a thicker window member, the upper die and the inner peripheral upper surface of the window member, and the lower metal member The thick portion is accommodated in the space formed between the mold and the inner peripheral lower surface of the window member, and there is an advantage that the molten resin can be sealed at the outer peripheral portion. Further, from the cavity corresponding to the molded product body formed between the upper mold and the lower mold, and the window member sandwiched between the two molds, to the concave portion formed in the upper mold or the lower mold. Is short during injection molding,
Air from inside the cavity is easily evacuated to the recess, and can be discharged through the recess. Also, in the welded portion, since the concave portion improves the air bleeding, it is effective in preventing molding defects such as burning and short-circuiting.

When the upper mold and the lower mold are clamped, the upper mold and the lower mold are combined with each other between the upper mold and the outer peripheral portion of the window member and between the lower mold and the window member so as to have a range of -30 to 30. +30 μm
, Preferably between 0 and +20 μm. In the present invention, the term “negative interval” means that the interval between the upper mold and the lower mold in a portion that sandwiches the outer peripheral portion of the window member is smaller than the thickness of the outer peripheral portion of the window member. That is, it means that an allowance is provided for holding the window member by the upper mold and the lower mold. In addition, the positive interval means that the interval between the upper mold and the lower mold in a portion sandwiching the outer peripheral portion of the window member is formed to be wider than the thickness of the outer peripheral portion of the window member. That is, in holding the window member by the upper mold and the lower mold, it means that a gap is provided between the upper mold and the lower mold and the outer peripheral portion of the window member. If the pushing allowance at the time of holding the window member is too large, the sealing property of the molten resin at the outer peripheral portion of the window member is improved, but the occurrence of scratches at the outer peripheral portion, deterioration of air bleeding, burning at the weld portion, short circuit, etc. May be caused. On the other hand, if the gap between the upper mold and the lower mold and the outer peripheral portion of the window member is too large, the sealing property of the molten resin in the outer peripheral portion is deteriorated, and burrs may be generated. By setting this gap to such an extent that burrs do not occur, that is, by setting an appropriate plus interval, it is possible to seal the molten resin in the outer peripheral portion, and it has no scratches and good air bleeding. Can be

Furthermore, in the method of the present invention, it is advantageous to use an injection mold having a deformation preventing portion provided in at least one of the upper mold and the lower mold. The deformation preventing portion is provided on the side opposite to the gate or on the gate side with the window member interposed therebetween. The deformation preventing portion may be protruded from at least one of the lower surface or the upper surface of the upper mold or the lower mold, or may be formed. When the deformation preventing portion is protruded from the upper mold or the lower mold, the deformation preventing portion is arranged on the side opposite to the gate so that the side end of the outer peripheral portion of the window member abuts to prevent deformation. Or a fitting portion formed at the side end of the outer peripheral portion of the window member corresponding to the deformation preventing portion protruding from the upper mold or the lower mold. The parts may be arranged so as to fit each other. If the upper mold or the lower mold is provided with a deformation preventing portion, a projection fitted to the deformation preventing portion is formed in the window member. Here, in order to further reduce the damage to the window surface, the holding area of the window member by the mold is reduced, and the degree of polishing of the mold surface in contact with the window member is increased. The holding force may be reduced, and the injection pressure may deform the window member as shown in FIG. In general, deformation can be prevented by lowering the injection power by raising the resin temperature or the mold cooling water temperature, but there is a problem that the molding cycle becomes longer and the productivity is reduced. In the method of the present invention, by providing the deformation preventing portion, the deformation of the window member can be advantageously prevented without lengthening the molding cycle.

Further, when the deformation preventing portion is provided so as to protrude from a mold surface forming an inner surface of the molded product in the upper mold or the lower mold, a concave portion formed by the deformation preventing portion is formed inside the molded product. Therefore, in the case of a molded article whose appearance is regarded as important in terms of the quality of the molded article, no concave portion is formed on the outside, which is effective in maintaining the appearance. Further, in the case of a molded article whose appearance does not matter, the deformation preventing portion may be protruded from a mold surface forming an outer surface of the molded article in the upper mold or the lower mold. The shape of the deformation preventing portion is not particularly limited as long as it does not exceed the thickness of the molded article main body. When arranging the window member in the lower mold, the window member can be formed in consideration of easy arrangement and a reduction in the strength of the molded article main body. For example, it can be formed in a substantially trapezoidal cross-sectional shape having a height of about 30% of the thickness of the molded article main body.

The deformation preventing portion is provided at at least one position of the upper die or the lower die, and is appropriately disposed according to the shape of the molded product, the location of the window, and the like. The deformation preventing portion is at least one of the inner surfaces of the upper mold and the lower mold.
If it is protruded at the point, it protrudes from the mold surface on the opposite side of the gate across the window member, along the side edge of the outer peripheral portion of the window member, so as to contact all sides of the side edge. It may be installed, taking into consideration the shape of the molded product, the strength of the molded product near the outer periphery of the window, the flowability of the molten resin at the time of molding, gas release, etc. On the opposite side, a protrusion may be appropriately provided on the mold surface so as to contact a plurality of locations on the side end of the outer peripheral portion of the window member.

When the deformation preventing portion is formed in the upper mold or the lower mold, the deformation preventing portion is formed on either the gate side or the side opposite to the gate across the window member. You may have been. The deformation preventing portion may be a groove formed along the side edge of the outer peripheral portion of the window member, over the entire side of the side end, or partially on the mold surface, or may be a gate side. And may be engraved on the opposite side of the gate.

Furthermore, in the present invention, the shape of the joint between the outer peripheral portion of the window member and the molded article main body may be changed to a projecting joint projecting from the outer peripheral portion of the window member, and a molded product corresponding to the projecting joint. If the joint formed on the main body has a two-layer structure in which the total thickness of both joints is within the range of the thickness of the molded product, the joint area can be increased. As a result, a sufficient joining force can be obtained without providing an anchor portion. Also, at this time, by providing the projecting joint of the window member so as to be disposed on the inner surface side of the molded article main body, without impairing the appearance of the obtained molded article,
A joint can be formed.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a method of manufacturing a molded article having a window, a method of manufacturing an upper half of a DVC (digital video cassette) shown in FIG. 9, a method for producing a molded article having a window portion of the present invention (hereinafter, referred to as “method of the present invention”) will be described in detail, and a molded article having a window portion obtained by the method will be described in detail. explain.

In manufacturing the upper half of the DVC,
First, at the time of opening the mold, a window member is arranged at a predetermined position of the lower mold of the injection mold. At this time, as shown in FIG. 4 described later, the window member has at least one fitting portion corresponding to a positioning portion provided at a predetermined position of the lower mold, and the fitting portion is formed in the lower portion. The window member can be arranged at a predetermined position by fitting to the positioning portion of the mold. At this time, as shown in FIG. 4 described later, if air is sucked from the suction port provided in the lower mold, the arrangement of the window member can be performed more reliably and quickly. Since the member is held, the window member does not fall off during the closing of the mold, and the suction air pressure is detected, and the window member can be used for an interlock as to whether the holding of the window member has been confirmed.

Next, as shown in FIG. 1, the mold is closed and clamped, and the outer peripheral portion 3 of the window member 1 is held between the upper mold 5a and the lower mold 5b. At this time, the upper mold 5a has an upper concave portion 9 corresponding to the upper surface 7a of the inner peripheral portion of the window member 1.
a, and the lower mold 5b has a concave portion 9b which is recessed downward corresponding to the lower surface 7b of the inner peripheral portion of the window member, and the upper mold 5a and the lower mold 5 are formed by the concave portions 9a and 9b. The mold 5b does not contact the upper surface 7a and the lower surface 7b of the inner peripheral portion of the window member 1, and only the outer peripheral portion 3 of the window member 1
And the corresponding surface of the lower mold 5b, and the window member 1 is held in the mold.

As described above, the upper mold 5a and the lower mold 5
b, a molten resin is injected from a gate into a cavity 11 formed between the window member 1 disposed therein, and the molten resin is filled to form a molded article main body corresponding to the cavity 11. The outer periphery 3 of the window member 1 is
In the above, the upper half can be formed as a molded article integrally joined and having a window portion. At this time, since the upper mold 5a and the lower mold 5b do not contact the inner peripheral portion of the window member 1, no damage is caused on the inner peripheral portion by contact with the mold.

Further, the window member 1 is held at a predetermined position,
When the molten resin is injected into the mold in which the cavity 11 corresponding to the molded article main body is formed, the molten resin flowing from the gate causes the window member 1 to pass through the cavity 11 along the outer peripheral portion 3 of the window member 1. It flows around and merges on the opposite side of the gate to form a weld. Further, the upper mold 5a and the lower mold 5b are in contact with the window member 1 only at the outer peripheral portion 3, and the inner peripheral portion of the window member 1 is not in contact with the upper mold 5a and the lower mold 5b. Upper mold 5a and upper surface 7 of inner peripheral portion of window member 1
between a, and between the lower surface 7b of the inner peripheral portion of the lower mold 5b and the window member 1, respectively spatial B ₁ and B ₂ are formed. Therefore, when there is a partially thick portion in the inner peripheral portion of the window member 1, for example, even if the central portion of the window member 1 is thick, the upper mold 5a and the upper surface of the inner peripheral portion of the window member 1 are formed. 7a and the lower surface 7b of the lower mold 5b and the inner peripheral portion of the window member 1.
The thick portions are housed in the spaces B ₁ and B ₂ formed between the spaces, and there is an advantage that the molten resin can be sealed at the outer peripheral portion 3. Also, from the cavity, the upper mold 5a
Alternatively, since the distance to the concave portion 9a or 9b formed in the lower mold 5b is short, air from the inside of the cavity 11 is easily evacuated to the concave portion 9a or 9b during injection molding, and through the concave portion 9a or 9b. Can be discharged. Also, in the weld portion, the recess 9 is formed.
Since a or 9b improves air bleeding, it is effective in preventing molding defects such as burns and short circuits.

Here, in order to further reduce the damage to the window surface, the holding area of the window member by the mold is reduced, and the degree of polishing of the mold surface in contact with the window member is increased. The holding force of the window member may be reduced, and the injection pressure may cause the window member to be pushed by the molten resin from the gate, causing scratches on the window. In severe cases, the window member 121 may be deformed as shown in FIG. For example, as shown in FIG. 2, the window member 1 held between the upper mold 5a and the lower mold 5b is pushed in the arrow A direction by the pressure of the molten resin flowing from the gate in the arrow A direction. As a result, abrasion may occur due to friction with the upper mold 5a or the lower mold 5b, and when the pressure is large, the window member may be deformed as shown in FIG. .

In such a case, as shown in FIG.
It is effective to use an injection molding die in which the deformation preventing portion 13 is protruded from at least one portion of the lower die 5b (or the upper die 5a). The deformation preventing portion 13 is provided so as to project from the lower mold 5b (or the upper mold 5a) opposite to the gate with the window member 1 interposed therebetween. When the upper half of the DVC shown in FIG. 6 is molded by the injection mold including the lower mold 5b having the deformation preventing portion 13, first, a cross section viewed from the back side of the paper of FIG. As shown in FIG. 4, a fitting portion 17 of the window member 1 is fitted to a positioning portion 15 formed on the lower mold 5b, and a deformation preventing portion 13 protruding from the lower mold 5b is fitted with a window. The window member 1 is arranged at a predetermined position in the mold by bringing the outer peripheral edge 19 of the member 1 into contact. At this time, if air is sucked from the suction port 21 provided in the lower mold 5b and the window member is sucked to the lower mold, the arrangement of the window member can be performed more reliably and quickly, which is effective. .

Next, the mold is closed and clamped, and as shown in FIG. 3, only the outer peripheral portion 3 of the window member 1 is sandwiched by the upper mold 5a and the lower mold 5b. The window member 1 is held without the upper and lower molds 5a and 5b being in contact with the upper and lower surfaces 7a and 7b of the inner peripheral portion.
Then, in the cavity 11 formed between the upper mold 5a, the lower mold 5b, and the window member 1 arranged therein,
The cavity 11 is filled by injecting molten resin from the gate.
And at the same time, the window member and the molded article main body are integrally joined at the outer peripheral portion of the window member to form the upper half as a molded article having the window. At this time, the window member 1 has an outer peripheral edge 1 thereof.
9 is supported by the deformation preventing portion 13 with which the abutment 9 contacts.
The deformation of the window member 1 as shown in FIG. 12 is prevented by the injection pressure of the molten resin.

The upper half 23 whose inner surface is shown in FIG. 5 can be manufactured by the above method. The upper half 23 has a window 29 formed by integrally joining a window member 27 to a molded article main body 25. In the peripheral portion 31 of the window portion 29 corresponding to the side opposite to the gate in the mold, concave portions 33a, 33b, 33c and 33d are formed corresponding to the deformation preventing portions protruding from the lower mold. I have. Further, fitting portions 35 a and 35 b fitted to the positioning portion of the lower mold are integrally joined to the molded article main body 25 on the periphery of the window portion 29.

FIG. 6 is a schematic sectional view for explaining another example of the method of the present invention. In the example shown in FIG. 6, the upper mold 37 a of the injection molding mold corresponds to the upper surface 41 a of the inner peripheral portion of the window member 39, and has a concave portion 43 a concave upward.
The lower mold 37b has a deformation preventing fitting of the outer peripheral ends 45a and 45b corresponding to the outer peripheral ends 45a and 45b formed by bending both side ends of the window member 39 downward. Parts 47a and 47b are perforated.

In the method of manufacturing the upper half using the injection mold, first, the outer peripheral ends 45a and 45b of the window member 39 are formed by deforming the upper surface 41b of the lower mold 37b. The window member 39 is arranged at a predetermined position on the upper surface 47b of the lower mold 37b by fitting into the prevention portions 47a and 47b. Next, the mold is closed and the mold is clamped, and as shown in FIG.
b, only the outer peripheral portion of the window member 39 is sandwiched, and the upper and lower molds 37a and 37b of the inner peripheral portion of the window member 39 do not come into contact with each other, and the window member 39 is held. Is done.

Thereafter, the upper mold 37a and the lower mold 37b
Injects and fills a molten resin from a gate into a cavity 53 formed between the window member 39 disposed therein and the window member 39 to form a molded article main body corresponding to the cavity 53, and at the same time, forms the molded product body with the window member. The product main body is integrally joined at the outer peripheral portion of the window member, and the upper half is formed as a molded product having the window portion. At this time, the outer peripheral ends 45 a and 45 b provided at both ends of the window member 39 are
Since the protrusions 7a and 7b are fitted and sufficiently supported by the deformation preventing portions 47a and 47b, deformation of the window member as shown in FIG. 12 due to the injection pressure of the molten resin can be prevented.

FIG. 7 is a schematic sectional view for explaining another example of the method of the present invention. In the example shown in FIG. 7, the upper mold 55a of the injection molding mold has an upper concave portion 61a corresponding to the upper surface 59a of the inner peripheral portion of the window member 57.
The lower mold 55b is provided with a deformation preventing portion 65 to which a protrusion 63 protruding from the lower surface of one end of the outer peripheral portion of the window member 57 is fitted.
Are perforated.

In the method of manufacturing the upper half using the injection mold, first, the projection 63 of the window member 57 is formed.
Is fitted to the deformation preventing portion 65 formed in the upper surface 67b of the lower mold 55b, and the window member 57 is arranged at a predetermined position on the upper surface 67b of the lower mold 55b. Next, the mold is closed and the mold is closed. As shown in FIG. 7, only the outer periphery of the window member 57 is sandwiched by the upper mold 55a and the lower mold 55b, and the upper surface 59a of the inner periphery of the window member 57 is formed. And lower surface 59b
The window member 57 is held without contact between the upper mold 55a and the lower mold 55b.

Thereafter, the upper mold 55a and the lower mold 55b
Injects and fills a molten resin from a gate into a cavity 69 formed between the window member 57 disposed therein and the window member 57 to form a molded article body corresponding to the cavity 69, and at the same time, forms The product main body is integrally joined at the outer peripheral portion of the window member, and the upper half is formed as a molded product having the window portion. At this time, the projection 63 provided at one end of the window member 57 is formed by the deformation preventing portion 6 of the lower mold 55b.
5 and is sufficiently supported, so that the deformation of the window member as shown in FIG. 12 due to the injection pressure of the molten resin can be prevented.

FIG. 8A is a schematic sectional view showing another example of the method of the present invention, and FIG. 8B is a plan view showing a window member used in the method. This FIG.
In the example shown in FIG. 7, the upper mold 71a of the injection mold is used.
Has an upper concave portion 77a corresponding to the upper surface 75a of the window member 73, and the lower mold 71b is
The concave portion 77b which is concave downward corresponding to the lower surface 75b of the inner peripheral portion
Having. Also, as shown in FIGS. 8A and 8B, overhangs 79a, 79b,
79c, 79d and 79e are shaped. Each of the overhang portions 79a, 79b, 79c, 79d, and 79e has a fitting portion 81a, 81b, 81 fitted to a positioning portion provided on the lower mold 71b.
c, 81d and 81e are perforated.

As shown in FIGS. 8A and 8B, the overhang portion may be provided at a plurality of positions on the outer periphery of the window member, or may be formed over the entire outer periphery of the window member. . Further, as shown in FIGS. 8A and 8B, the overhang portion may be formed on the inner surface side of the molded article main body, or may be formed on the outer surface side. In particular, if the overhang is formed on the inner surface side of the molded article main body, the overhang is not exposed outside the obtained molded article, so that the appearance of the molded article is not impaired, and the appearance of the molded article is a problem Is advantageous.

In the method of manufacturing the upper half using the injection mold, first, the projecting portions 79a and 79a of the window member 73 are provided on the positioning portion provided on the lower mold 71b.
The fitting portions 81a of 79b, 79c, 79d and 79e,
81b, 81c, 81d and 81e are fitted to each other, and the window member 73 is arranged at a predetermined position.

Next, as shown in FIG. 8A, the mold is closed and the mold is closed, and the outer peripheral portion 83 of the window member 73 is held between the upper mold 71a and the lower mold 71b. At this time, the upper dies 71a and 71b do not contact the upper surface 75a and the lower surface 75b of the inner peripheral portion of the window member 73, and only the outer peripheral portion 83 of the window member 73 corresponds to the upper die 71a and the lower die 71b. The window member 73 is held in the mold.

Thereafter, the upper mold 71a and the lower mold 71b
Injects and fills a molten resin from a gate into a cavity 85 formed between the window member 73 and the window member 73 disposed therein, thereby forming a molded article main body corresponding to the cavity 85 and simultaneously forming the molded body with the window member. The product main body is integrally joined at the outer peripheral portion of the window member, and the upper half is formed as a molded product having the window portion. At this time, the window member 73 is fitted to the fitting portions 81a, 81b, 81 of the lower mold 71b at the projecting portions 79a, 79b, 79c, 79d, and 79e.
Since they are fitted and sufficiently supported by c, 81d and 81e, deformation of the window member as shown in FIG. 12 due to the injection pressure of the molten resin can be prevented.

As described above, the method of the present invention has been described taking the production of the upper half of the DVC as an example. However, the present invention is not limited to these examples, and can be applied to the production of various molded products having windows. For example, as shown in a waterproof case 101 of a film unit with a lens shown in FIG. 13, an exposure window 1 provided at a portion corresponding to a photographing lens 113 of a film unit with a lens 103 housed in a watertight state.
15. Also, the present invention can be suitably applied to the manufacture of a molded product having a window provided at a portion corresponding to a finder, a strobe, or the like.

[0046]

According to the method of the present invention, special equipment is required for forming a molded product in which the window portion and the molded product main body are joined with sufficient joining strength without appearance defects such as scratches and deformation. It can be manufactured at a low cost with simple steps using existing equipment. In addition, the window member contacts the upper mold and the lower mold only at the outer periphery, and the inner periphery of the window member does not contact the upper mold and the lower mold. Spaces are formed between the upper surfaces and between the lower mold and the inner peripheral lower surface of the window member. Therefore, when there is a partially thick portion in the inner peripheral portion of the window member, for example, even if the central portion is a thicker window member, between the upper mold and the inner peripheral upper surface of the window member,
Also, there is an advantage that the thick portion is accommodated in a space formed between the lower mold and the inner peripheral lower surface of the window member, and the molten resin can be sealed at the outer peripheral portion.

Further, since the distance from the cavity to the concave portion formed in the upper mold or the lower mold is short, air from the cavity is easily released into the concave portion during injection molding, and is discharged through the concave portion. Can be done.
Also, in the welded portion, the concave portion improves the air bleeding, which is effective in preventing molding defects such as burning and short-circuiting.

Furthermore, the molded article obtained by the method of the present invention has no noticeable damage to the window at the easily visible window, no deformation or other defective appearance, and has a sufficient joint between the window and the molded article main body. They are joined with strength.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating main steps of manufacturing an upper half of a digital video magnetic tape cassette (DVC) by applying the method of the present invention.

FIG. 2 is a schematic cross-sectional view illustrating movement of a window member during injection of a molten resin.

FIG. 3 is a schematic cross-sectional view illustrating main steps of manufacturing an upper half of a digital video magnetic tape cassette (DVC) using an injection molding die having a deformation preventing portion in the method of the present invention.

FIG. 4 is a schematic cross-sectional view illustrating main steps of manufacturing an upper half of a digital video magnetic tape cassette (DVC) using an injection mold having a deformation preventing portion in the method of the present invention.

FIG. 5 is a diagram illustrating an inner surface of an upper half of a digital video magnetic tape cassette (DVC) manufactured by applying the method of the present invention.

FIG. 6 is a schematic sectional view showing another example of the method of the present invention.

FIG. 7 is a schematic sectional view showing another example of the method of the present invention.

FIG. 8A is a schematic sectional view showing another example of the method of the present invention, and FIG. 8B is a plan view showing a window member used in the method.

FIG. 9 shows a DVC manufactured by applying the method shown in FIG.
It is a schematic cross section which shows the structure of the upper half.

10A is a perspective view of an upper half of a digital video magnetic tape cassette (DVC), and FIG.
Is a sectional view of the same.

FIG. 11 is a schematic cross-sectional view illustrating a step of manufacturing a molded article having a window by a conventional insert molding method.

FIG. 12 is a conceptual diagram illustrating deformation of a window in insert molding.

FIG. 13 is a diagram illustrating a waterproof case for a film unit with a lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Window member 3 Outer peripheral part 5a Upper die 5b Lower die 7a Upper surface of inner peripheral part 7b Lower surface of inner peripheral part 9a, 9b Concave part 11 Cavity 13 Deformation preventing part 15 Positioning part 17 Fitting part 19 Outer peripheral part 21 Suction port 23 Upper half 25 Molded product main body 27 Window member 29 Window 31 Peripheral edge 33a, 33b, 33c, 33d Recess 35a, 35b Fitting portion 37a Upper die 37b Lower die 39 Window member 41a Upper surface of inner peripheral portion 41b Inner peripheral portion Lower surface 43a concave portion 45a, 45b outer peripheral end portion 47a, 47b deformation preventing portion 49b upper surface 51 outer upper surface 53 cavity 55a upper mold 55b lower mold 57 window member 59a inner peripheral upper surface 59b inner peripheral lower surface 61a concave 63 Projection 65 Deformation prevention part 67b Upper surface 69 Cavity 71a Upper mold 71b Lower mold 73 Window member 75a Upper surface of inner peripheral portion 75b Lower surface of inner peripheral portion 77a, 77b Concave portions 79a, 79b, 79c, 79d, 79e Overhang portions 81a, 81b, 81c, 81d, 81e Fitting portion 83 Outer portion 85 Cavity 91 Upper half 93 Window member 95a , 95b, 95c, 95d Outer portion 97 Upper half body 99a, 99b, 99c, 99d Inner end of window opening 101 Waterproof case 103 Film unit with lens 105 Release lever 107 Operation dial 109 Case body 111 Bottom cover 113 Photographing lens 115 Exposure window 117a Upper mold 117b Lower mold 119 Window member 121 Window member

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) B29K 105: 20 B29L 11:00 31:34 (72) Inventor Morio Fujiwara 2-12-1, Ogimachi, Odawara-shi, Kanagawa Wealth F-Term (in reference) 2H100 BB04 4F202 AD04 AD05 AH38 AH73 AM32 AM33 CA11 CB12 CK06 CK25 CQ03 CQ05 4F206 AD04 AD05 AH38 AH73 AM32 AM33 JA07 JB12 JF05 JL02 JN25 JQ06 JQ81

Claims (3)

[Claims] 1. A window in which molten resin is injected and filled around a window member held at a predetermined position in an injection molding die, and the window member and a molded article main body are integrally joined. A method for manufacturing a molded article having a portion, comprising: using an injection molding mold including an upper mold and a lower mold having a concave portion corresponding to an inner peripheral portion of a window member; Only the part is sandwiched between the upper mold and the lower mold,
Holding the inner peripheral portion of the window member so as not to contact the upper mold and the lower mold, and filling the molten resin into the injection molding mold; Production method. 2. The window according to claim 1, wherein the injection mold has a deformation preventing portion of a window member provided at least at one position of an upper mold or a lower mold. A method for producing a molded article having a part. 3. A molded article having a window, produced by the method according to claim 1.