JPH09207176A - Mold assembly for injection compression molding and injection compression molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To faithfully transfer the surface of a cavity to the surface of a molded product by determining the clearance value between a core and a press plate and setting the press flange of the press plate to the core to a predetermined value or more. SOLUTION: The clearance C between a core 40 and a press plate 42 is set to 0.001-0.03mm. When the clearance C exceeds 0.03 mm, a molten resin penetrates into the gap between the core 40 and the press plate 42 and a crack is generated in the core 40 according to cercumstances and a problem such that burr is generated on a molded product is also generated. When the flange ΔS of the press plate 42 to the core is below 0.1mm, the crazes generated in the core 40 at a time of the production of the core 40 come into contact with a molten resin and, as a result, the crazes generated in the core 40 are grown to a crack and the core 40 is damaged according to circumstances.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold assembly for injection compression molding, and an injection compression molding method using the mold assembly.

[0002]

2. Description of the Related Art Usually, dies are made of carbon steel, stainless steel,
It is made of a metal material such as an aluminum alloy or a copper alloy. Since these metal materials have good thermal conductivity, the molten resin injected into the cavity provided in the mold has a surface that constitutes the cavity of the mold (hereinafter referred to as the cavity surface of the mold for convenience). When they come into contact, they begin to cool immediately. As a result, the surface layer portion of the molten resin is rapidly solidified, so that for example, when a fiber reinforced resin material is used as the raw material resin of the molded product, the fiber is likely to be exposed on the surface of the molded product. In addition, since the solidified layer rapidly develops in the molten resin near the cavity surface of the mold, the wettability between the cavity surface of the mold and the resin is poor, and the cavity surface of the mold is adhered to It is difficult to transfer to the surface.

Further, since the solidification rate of the molten resin in the cavity is high, it is difficult for the pressure to reach the inside of the molded product, and sink marks are likely to occur in the molded product. Particularly in the case of thick-walled molded products and ordinary molded products. However, there is a problem that sink marks are likely to occur at the end of the molded product.

In order to solve these problems, generally, a method of injecting a molten resin at a high pressure to forcibly transfer the cavity surface of the mold to the surface of the molded article, or raising the mold temperature to a high temperature. The method of delaying the development of the solidified layer of the molten resin is taken. However, in the former method, the size of the injection molding device is increased, the size of the mold itself is increased, and the cost is increased due to the increase in wall thickness, and stress remains inside the molded product due to high-pressure filling of the molten resin in the cavity. However, as a result, there arises a problem that the quality of the molded product deteriorates. On the other hand, in the latter method, since the mold temperature is set close to the load deflection temperature of the resin, the cooling time of the resin in the cavity becomes longer, resulting in a longer molding cycle and lower productivity. There is.

[0005]

When the mold part forming the cavity is made of a low heat conductive material, it is possible to delay the development of the solidified layer of the molten resin. as a result,
It is possible to mold a molded product having a clean surface with excellent transferability of the cavity surface of the mold to the surface of the molded product. However, when a mold is made of a low heat conductive material, it is difficult to completely eliminate sink marks due to the delay in the development of the solidified layer of the molten resin.

[0006] In addition, when the mold portion constituting the cavity is made of such a low heat conductive material, the solidified layer is slow to develop, depending on the raw material resin used, so that the cavity surface of the mold is The wettability with the molten resin is improved. As a result, there is a problem that a vacuum state is created between the cavity surface of the mold and the resin (molded product), and it becomes extremely difficult to release the molded product from the mold. In such a case, if the molded product is forcibly released from the mold, the molded product may be deformed, or the cavity surface of the mold may be damaged or damaged.

Therefore, a first object of the present invention is that the surface constituting the cavity can be faithfully transferred to the surface of the molded product, enabling the molding of a molded product with excellent quality,
An object of the present invention is to provide a mold assembly for injection compression molding and an injection compression molding method capable of reliably preventing the occurrence of sink marks in a molded product without causing extension of the molding cycle. Furthermore,
A second object of the present invention is to provide, in addition to the first object, a mold assembly for injection compression molding and an injection compression molding method that can easily release a molded product from a mold.

[0008]

SUMMARY OF THE INVENTION A mold assembly for injection compression molding according to the present invention for achieving the above first object comprises:
(A) It is composed of a first mold part and a second mold part, and when a mold is clamped, a cavity for molding a molded product based on a thermoplastic resin is formed inside, and when a molded product is molded, A mold having a structure capable of varying the volume of the cavity, and (b)
It is arranged in the first and / or second mold part and constitutes a part of the cavity, and has a thickness of 0.5 mm to 10 mm, preferably 1 mm to 7 mm, more preferably 2 mm to 5
mm ceramic or glass insert,
(C) A retaining plate that is attached to the mold part in which the nest is arranged, forms a part of the cavity, and restrains the end of the nest, and a clearance (C ₀ between the nest and the restraining plate). ) Is 0.001 to 0.03 mm
(0.001 mm ≦ C ₀ ≦ 0.03 mm), and the pressing margin (ΔS) of the pressing plate with respect to the insert is 0.1 mm or more (ΔS ≧ 0.1 mm).

Depending on the shape of the molded product to be molded, the required surface characteristics, etc., the insert may be arranged only in the first mold part or only in the second mold part. Alternatively, it may be provided in both the first mold part and the second mold part.

Here, forming a part of the cavity means forming a cavity surface which defines the outer shape of the molded product. More specifically, the cavity includes, for example, a surface forming a cavity formed in the first mold part and the second mold part, a surface forming a cavity formed in the nest, and a pressing plate. And the surface forming the formed cavity. The surfaces forming these cavities are hereinafter referred to as cavity surfaces. An element forming a cavity surface provided on the side of the first die portion corresponding to the female die (cavity portion) and a cavity surface provided on the side of the second die portion corresponding to the male die (core portion) Table 1 below shows combinations with the elements that constitute the. When the elements forming the cavity surface are (first mold part or second mold part) + (nesting) + (holding plate), the end of the nest is held down by the holding plate. Therefore, the edge of the holding plate is left on the surface of the molded product.

[0011]

[Table 1] (1) First mold part side: first mold part + nesting + holding plate Second mold part side: (1-1) second mold part: (1 -2) Second mold part + nesting + pressing plate: (1-3) Nesting + pressing plate (2) First mold part side: Nesting + pressing plate Second mold part side: ( 2-1) Second mold part: (2-2) Second mold part + nesting + pressing plate: (2-3) Nesting + pressing plate (3) First mold part side: No. 1st mold part 2nd mold part side: (3-1) 2nd mold part + nesting + restraining plate: (3-2) nesting + restraining plate

If the thickness of the insert is less than 0.5 mm, the heat insulating effect due to the insert is reduced, the molten resin introduced into the cavity is rapidly cooled, and there is a possibility that appearance defects such as weld marks and flow marks occur. Get higher Also,
When fixing the insert to the mold part, for example, a thermosetting adhesive may be used to adhere the insert to the mold part. However, when the insert thickness is less than 0.5 mm, the thickness of the adhesive If the mold is not uniform, uneven stress remains in the insert, so that the surface of the molded product may undulate, or the insert may be damaged by the pressure of the injected molten resin. On the other hand, when the thickness of the insert exceeds 10 mm, the heat insulation effect of the insert becomes too large, and the molded product may be deformed after the molded product is taken out from the mold unless the cooling time of the resin in the cavity is extended. . Therefore, problems such as extension of the molding cycle may occur.

The clearance (C ₀ ) between the insert and the holding plate is 0.001 mm or more and 0.03 mm or less (0.001 mm ≦ C ₀ ≦ 0.03 mm). Here, the clearance (C ₀ ) is a gap between the insert and the holding plate, which is measured along the thickness direction of the insert. The minimum value of the clearance (C ₀ ) is that when the restraint plate is attached, fine cracks are generated in the outer periphery of the insert, and the insert and the restraint plate come into contact with each other due to thermal expansion of the insert when the die is heated. The value is such that, as a result of stress being applied to the microcracks on the outer peripheral portion of the insert, the insert is damaged, or the insert is not damaged by the impact during mold clamping. Also, the clearance (C
_{If 0} ) exceeds 0.03 mm, the molten resin may invade between the insert and the restraining plate, cracking may occur in the insert, and burrs may occur on the molded product.

When the pressing margin (ΔS) is less than 0.1 mm,
As a result of contacting the craze generated in the nest with the molten resin at the time of producing the nest, the craze generated in the nest may grow into cracks and the nest may be damaged. Suppression allowance (Δ
Although the upper limit of S) is not particularly specified, it is preferably about 2 mm. Here, the pressing margin (ΔS) is the distance from the end surface (side surface) of the pressing plate to the end of the insert along the cavity surface of the insert.

It is preferable that the die has a structure in which a cage structure is formed by the parting surface of the first die part and the parting surface of the second die part. Here, the "ingarment structure" means that the parting surface of the first die part and the parting surface of the second die part face each other, and a cavity is formed even if the die is not completely clamped. As described above, the parting surface of the first mold part and the parting surface of the second mold part are slidable with each other with a slight clearance.
Refers to a structure in which the mold part and the second mold part are fitted together. Depending on the case, a printing basket structure may be formed by the end surface (side surface) of the holding plate attached to the first mold part and the parting surface of the second mold part, or the second mold part. The cage structure may be formed by the end surface (side surface) of the holding plate attached to the mold part and the parting surface of the first mold part, or may be attached to the first mold part. The cage structure may be formed by the end surface (side surface) of the pressing plate and the end surface (side surface) of the pressing plate attached to the second mold part.

In the mold assembly of the present invention, although depending on the raw material resin used, the solidified layer develops slowly, so the surface forming the cavity of the molten resin and the nest (hereinafter referred to as the cavity surface of the nest). ) Is improved, and as a result, a vacuum is created between the resin (molded product) and the cavity surface of the insert, which may make it difficult to separate the insert from the insert. In such a case, that is, in order to achieve the above second object, the mold assembly of the present invention is
A protrusion pin slidably disposed in the first mold unit is further provided, and a clearance (C ₁ ) between the protrusion pin and the first mold unit is 0.01 to 0.03 mm (0.01 mm).
≦ C ₁ ≦ 0.03 mm), and the gap between the protruding pin and the first mold part and the gap between the insert and the restraining plate are connected to a fluid source, and after molding the molded product, When the molded product is opened and the molded product is released from the first mold part using the projecting pin, the fluid flows through the space between the projecting pin and the first mold part and the space between the nest and the restraining plate. It is preferable to have a structure capable of flowing. As the fluid source, for example, a compressed air source or a pressurized nitrogen gas source can be used, and in this case, the fluid is compressed air or pressurized nitrogen gas. The first
In the mode in which the pressing plate is attached to the mold part of and the protruding pin is arranged to pass through the pressing plate,
It is included in the aspect in which the projecting pin is arranged in the first mold part.

In the region from the tip of the projecting pin to about 5 mm or from the tip of the projecting pin to about 30 mm, the above-mentioned clearance (C ₁ ) exists between the projecting pin and the first mold part. Good. In the other regions, considering the fluid flow, the clearance between the protruding pin and the first mold part is 0.5 mm to 5 mm.
mm is preferable. If the clearance (C ₁ ) between the protruding pin and the first mold part is less than 0.01 mm, it becomes difficult to flow the fluid from the gap between the protruding pin and the first mold part. On the other hand, when the clearance (C ₁ ) between the projecting pin and the first mold part exceeds 0.03 mm, the molten resin may enter the gap between the projecting pin and the first mold part.

The thermal conductivity of the material forming the insert is 2 × 10 5 for the purpose of preventing the molten resin in the cavity from being rapidly cooled.
⁻² cal / cm · sec · deg or less is required. When a nest is made using a material having a thermal conductivity exceeding this value, the molten resin in the cavity is rapidly cooled by the nest, so a mold made of ordinary carbon steel without a nest is used. Only the same appearance as the molded product can be obtained.

The nest has a thermal conductivity of 2 × 10 ^-2 cal /
It is composed of soda glass, quartz glass, heat-resistant glass, or crystallized glass, which is widely selected from the group consisting of zirconia-based materials, alumina-based materials, and K ₂ O-TiO ₂ and has a size of cm · sec · deg or less. It can be made from a glass selected from the group, more specifically ZrO ₂ , ZrO ₂ —CaO, ZrO ₂ —Y ₂ O ₃ , Z
_{rO 2 -MgO, K 2 O-} TiO 2, Al 2 O 3, Al 2 O 3
_{-TiC, Ti 3 N 2, 3Al} 2 O 3 ceramic selected from the group consisting of -2SiO _2, or be made of soda glass, quartz glass, heat resistant glass, glass selected from the group consisting of crystallized glass However, the thermal conductivity is 2 × 10 ^-2 cal / cm · sec · d.
eg at most, ZrO ₂ -Y ₂ O ₃ or 3Al ₂ O ₃ · ₂
It is preferably made of a ceramic composed of SiO ₂ .

Alternatively, the nest has a thermal conductivity of 2 × 1.
0 ^-2 or less cal / cm · sec · deg, a crystallinity of 10% or more, more preferably a crystallinity of 60% or more, more preferably from 70% to 100% of the crystallized glass crystallinity of It is preferable to make them. When the crystallinity is 10% or more, the crystals are uniformly dispersed throughout the glass,
Since the thermal shock strength and the interfacial peeling property are remarkably improved, it is possible to remarkably reduce the damage of the insert during molding of the molded product. If the crystallinity is less than 10%, there is a drawback that interface peeling easily occurs from the surface during molding.

The thermal shock strength is 1 when heated to a predetermined temperature.
The strength is defined as the temperature at which glass breaks when it is thrown into water at 25 ° C. at a temperature of 00 mm × 100 mm × 3 mm. Thermal shock strength is 400 ° C
Is 100 mm x 100 m heated to 400 ° C
This means that when an m × 3 mm glass is thrown into water at 25 ° C., the glass does not crack. This thermal shock strength can be obtained only at a value of around 180 ° C. even in heat resistant glass. Therefore, when the resin melted at a higher temperature (for example, about 300 ° C.) comes into contact with the cold insert, the insert may be distorted and the insert may be damaged. Thermal shock strength is also related to the crystallinity of glass,
If the insert is made of crystallized glass having a crystallinity of 0% or more, it is possible to reliably prevent the insert from cracking during molding.

Here, the crystallized glass means 1600 after adding a small amount of a nucleating agent of TiO ₂ and ZrO _{2 to} the raw glass.
After being melted at a high temperature of ° C or higher, it is molded by a press, blow, roll, cast method, etc., and further heat-treated for crystallization to obtain Li ₂ O-Al ₂ O ₃ -Si in the glass.
An example is one in which an O ₂ -based crystal is grown and a main crystal phase is a β-eucryptite-based crystal and a β-spodumene-based crystal. Alternatively, CaO-Al ₂ O ₃
After melting the SiO ₂ -based glass at 1400 to 1500 ° C., moving it into water and crushing it to make it into small particles, and then accumulating it, forming it into a plate shape on a refractory setter, and further performing heat treatment,
It can be exemplified that the β-wollastonite crystal phase is generated. _{Furthermore, SiO 2 -B 2 O 3 -Al} 2 O 3 -
And that to produce a mica crystal by heat-treating MgO-K ₂ O-F-based glass, MgO-Al ₂ O ₃ -SiO containing nucleating agent
An example is one in which cordierite crystals are generated by heat-treating a ₂ type glass. In addition, it is preferable to use crystallized glass having β-eucryptite-based crystals or β-spodumene-based crystals excellent in strength and thermal characteristics as the nest in the present invention.

In these crystallized glasses, the ratio of crystal particles present in the glass substrate can be expressed by an index called crystallinity. Then, the crystallinity can be measured by measuring the ratio of the amorphous phase and the crystalline phase using an analytical instrument such as X-ray diffraction.

When the molded product is required to have a mirror surface property, it is desirable that the surface roughness R _max of the cavity surface of the insert be 0.03 μm or less. For that purpose, the surface roughness R _max is 0.03 μm with respect to the cavity surface of the produced nest.
For example, diamond lapping may be performed until m or less, and if necessary, cerium oxide lapping may be performed. Lapping can be performed using a lapping machine or the like. Compared with the usual polishing of carbon steel or the like, for example, in the case of crystallized glass, a mirror surface can be obtained at a cost of about 1/2, so that the manufacturing cost of the mold assembly can be reduced. The surface roughness R _max is measured by
It was based on JIS B0601. When molding a molded product having a matte or heller-lined surface, the cavity surface of the nest may be subjected to sandblasting or etching to form fine irregularities or lines on the cavity surface of the nest.

The material forming the insert can be easily processed into irregularities, curved surfaces, etc. by ordinary grinding, and can be manufactured into any shape other than a considerably complicated shape. A nest can be produced by putting ceramic powder or molten glass in a mold, press-molding it, and then heat-treating it. Further, the nest can also be produced by naturally shaping the glass plate-like object placed in the mold in the furnace.

When molding a molded product having a three-dimensional shape or a curved surface, the mold fitting portion of the mold is fitted to the mold according to the curvature of the back surface of the mold (the surface opposite to the cavity surface of the mold and facing the mold). It suffices to machine and grind the restraining plate according to the curvature of the cavity surface of the nest. Also in this case, ΔS ≧ 0.1 mm and 0.00
While maintaining the relationship of 1 mm ≦ C ₀ ≦ 0.03 mm, the insert is attached to the insert attachment portion of the mold, and the insert is suppressed and the plate is suppressed.

At least one of the first mold section and the second mold section is provided with a nest mounting section for mounting a nest. In the mold assembly of the present invention, the part of the mold part on which the insert is mounted may be composed of the core mounted on the mold part.

After the insert is processed into a predetermined shape by grinding or the like, when the insert is not attached, there is no possibility that the insert will be dropped from the insert mounting portion provided in the mold part and damaged, or without using an adhesive. When the insert is attachable to the insert attachment part, the insert can be directly attached to the insert attachment part provided in the mold part without using an adhesive.
Alternatively, the insert may be adhered to the insert mounting portion using a thermosetting adhesive selected from epoxy, urethane, acrylic, and the like. However, it is desirable to make the thickness of the adhesive as thin and uniform as possible in order to prevent the nest from being distorted due to the uneven thickness of the adhesive.

The injection compression molding method of the present invention for attaining the above-mentioned first object is (a) composed of a first mold part and a second mold part, and is made of a thermoplastic resin during mold clamping. A mold having a cavity for molding a molded product based on a resin, and having a structure capable of varying the volume of the cavity when molding the molded product, and (b) the first and / or second mold. It is arranged in the mold part and constitutes a part of the cavity, and has a thickness of 0.5 mm to 10 mm.
And a nesting plate made of ceramic or glass of (c), and (c) a pressing plate that is attached to the mold part in which the nesting is arranged, forms a part of the cavity, and suppresses the end of the nesting. The clearance between the holding plate and the holding plate is 0.001 to 0.03 mm, and the holding amount of the holding plate with respect to the insert is 0.1 mm.
Or in which an injection compression molding method using a mold assembly, (A) the volume of the cavity than moldings volume to be molded (V _M) (V _C) so that larger, first A step of clamping the mold part and the second mold part, a step of (B) injecting a molten thermoplastic resin into a cavity having a volume (V _C ), and (C) an injection of the thermoplastic resin. Simultaneously with the start, during the injection, or after the completion of the injection (including the same time as the completion of the injection), the step of reducing the volume of the cavity to the volume (V _M ) of the molded product to be molded, and (D) the heat in the cavity. After cooling the plastic resin, the obtained molded product is released from the mold.

In the above step (A), the relationship between the volume (V _M ) of the molded product to be molded and the volume (V _C ) of the cavity is that the thickness of the molded product to be molded is t ₀ , and the process (A ), When the distance of the cavity in the thickness direction of the molded product is t ₁ and Δt = t ₁ −t ₀ , 0.1 mm ≦ Δt ≦ 6
It is preferable that the relationship is mm. Δt <
With a thickness of 0.1 mm, it is difficult to mold a molded product using a molten resin having poor fluidity, and the stress remaining in the molded product cannot be reduced. If Δt> 6 mm, air may be trapped in the molded product, which may deteriorate the quality of the molded product.

In order to achieve the above second object, in the injection compression molding method of the present invention, the mold assembly is provided with the first
Further includes a projecting pin slidably disposed in the mold part, wherein the clearance (C ₁ ) between the projecting pin and the first mold part is 0.01 to 0.03 mm, The gap between the first mold part and the gap between the insert and the restraining plate are connected to the fluid source, and after the molded product is molded, the mold is opened and the first pin is used by using the protruding pin. When releasing the molded product from the mold part, it is preferable to flow the fluid through the gap between the protruding pin and the first mold part and the gap between the insert and the restraining plate.

The insert in the injection compression molding method of the present invention is preferably made of various materials described above in the mold assembly for injection compression molding of the present invention.

The thermoplastic resin which is the raw material resin used in the present invention includes polystyrene resin, ABS resin and AE.
Polyester resin such as S resin, AS resin, methacrylic resin, polycarbonate resin, modified PPE resin, polysulfone resin, polyethersulfone resin, polyarylate resin, polyetherimide resin, polyamideimide resin, PET resin, polyamide resin, polyimide resin , Polyphenylene sulfide resin, POM resin, P
BT resin, polyetherketone resin, polyetheretherketone resin, polyolefin resin such as polyethylene resin and polypropylene resin, polyamide MXD6
Polyamide resin such as resin, polyacetal resin,
Examples include thermoplastic resins such as polyester carbonate resins, liquid crystal polymers and elastomers, and alloy resin compositions composed of two or more of these resins.

Further, 1% by weight of these thermoplastic resins is used.
Inorganic fibrous fillers, organic fibrous fillers, fillers, materials obtained by coating these with metal materials, stabilizers, ultraviolet absorbers, dyes and pigments can be added within the range of 50 to 50% by weight. If it exceeds 50% by weight, the inorganic fibrous filler or the like may be deposited on the surface of the molded product. Examples of the inorganic fibrous filler include glass fiber, carbon fiber, wollastonite, aluminum borate whisker fiber, potassium titanate whisker fiber, basic magnesium sulfate whisker fiber, calcium silicate whisker fiber and calcium sulfate whisker fiber. it can.

In the present invention, the insert is made of a material having a low thermal conductivity, and is made independently of the mold and disposed inside the mold, so that the insert has a large heat insulating effect. Not only that, maintenance of the nest is easy.
Further, it is possible to fabricate a nest that is resistant to thermal shock and is unlikely to be damaged or cracked. As a result, it can be used for a long period of time, and a weld line or the like is unlikely to occur in the molded product.

In the mold assembly of the present invention, the heat insulation effect by the nesting is great, the rapid cooling of the molten resin introduced into the cavity can be suppressed, and the appearance defects such as weld marks and flow marks occur. Can be effectively prevented. Moreover, by suppressing the nesting by the restraint plate within the range of the predetermined clearance (C ₀ ) and restraint allowance (ΔS), the appearance of the end of the molded product is not spoiled and burrs do not occur at the end of the molded product. Furthermore, since the fine cracks generated in the outer peripheral portion of the insert and the molten resin do not contact each other, the insert is not damaged.

By adopting the injection compression molding method of the present invention, a molded product can be molded even when a molten resin having poor fluidity is used. Further, since the injection pressure of the molten resin can be reduced, the pressure applied to the nest can be reduced, so that the deformation or damage of the nest can be effectively prevented. In addition, the stress remaining in the molded product can be reduced, and a molded product of high quality can be molded. Furthermore, since it becomes possible to uniformly compress the surface of the molded product, it is possible to suppress the occurrence of sink marks on the surface of the molded product.

Especially when using plastics such as engineering plastics and super engineering plastics which are excellent in heat resistance and strength but have poor moldability, molding is usually carried out at a mold temperature of 80 ° C. or higher, but flow marks, etc. There are a lot of poor appearances.
However, since the heat insulating effect is obtained by using the mold assembly of the present invention, it is possible to obtain a molded product having good appearance characteristics even if the mold temperature is 80 ° C. or lower. It may also be a thermoplastic resin with a filler added, in this case,
A phenomenon in which the filler is not deposited on the surface of the molded product does not occur, and a molded product having excellent appearance characteristics such as specularity can be obtained. This is because cooling and solidification of the injected molten resin can be delayed by nesting, and as a result, the fluidity and transferability of the molten resin can be improved.

Moreover, in addition to adopting the injection compression molding method, since the flowability of the molten resin is improved due to the presence of the nest, the injection pressure of the molten resin can be set lower.
The stress remaining in the molded product can be relaxed. As a result, the quality of the molded product is improved. Further, since the injection pressure can be reduced, the mold can be made thinner, the molding apparatus can be downsized, and the cost of the molded product can be reduced.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings based on preferred embodiments.

(Embodiment 1) FIG. 1 shows an overall conceptual view of a mold assembly of the present invention. The mold includes a first mold part 10 (corresponding to a cavity part which is a female mold, and a movable mold part in the first embodiment) and a second mold part 20 (a core which is a male mold). (Corresponding to a fixed mold part in the first embodiment). First and second mold parts 1
Each of Nos. 0 and 20 is attached to a mounting plate, and mold clamping and mold opening are possible, but detailed illustration of the mold opening / closing mechanism is omitted. Further, although the mold assembly is attached to the injection molding device, the illustration of the injection molding device is also omitted. At the time of mold clamping, a cavity 31 for molding a molded product is formed inside the mold based on the thermoplastic resin. FIG.
2A shows the mold opening state, FIG. 2A shows the mold clamping state before injection of the molten resin (Δt> 0), and FIG. 2B shows after the injection of the molten resin is completed. The arrangement | positioning state of the 1st metal mold | die part 10 and the 2nd metal mold | die part 20 during cooling the resin in a cavity is shown ((DELTA) t = 0). In addition, in FIG.
Illustration of the molten resin is omitted. The reference number 30 is the second
It is a molten resin injection part provided in the mold part 20 of FIG.

A schematic end view of the enlarged mold assembly in the area around the cavity 31 is shown in FIG. In the first embodiment, the nest 40 is arranged in the first mold part 10, and the nest 40 constitutes a part of the cavity. In the first embodiment, the surface 41 forming the cavity of the nest 40 (hereinafter, also referred to as the cavity surface 41 of the nest) constitutes all of the cavity surface on the first mold part side. In the first embodiment, the nest 40 is the core 1.
It is attached to 1.

Suppression plate 42 made from S55C
Is attached to the first mold part 10 in which the insert 40 is arranged using screws (not shown). The restraining plate 42 restrains the end portion of the insert 40 in a non-contact state with a restraint allowance = ΔS and a clearance = C ₀ , and constitutes a part of the cavity 31.

Projecting pin insertion holes 52 and 53 are provided in the first mold part 10 and the holding plate 42, and the projecting pin 50 is inserted into these projecting pin insertion holes 52 and 53. The tip of the protruding pin 50 is the cavity 3
Faces one. The rear end of the projecting pin 50 is attached to a drive device (not shown) including, for example, a hydraulic cylinder.

A fluid introducing section 51 is formed in the first mold section. The fluid introducing part 51 is connected to a fluid source (not shown) by a pipe (not shown). by this,
After the molded product is molded, the mold is opened, and when the molded product is released from the first mold part 10 using the projecting pin 50, a gap between the projecting pin 50 and the first mold part 10 ( More specifically, it becomes possible to flow the fluid from a gap between the protruding pin 50 and the protruding pin insertion hole 53. At the same time, it becomes possible to flow the fluid from the gap between the insert 40 and the restraining plate 42 via the gap between the first mold part 10 and the core 11. The clearance between the projecting pin 50 and the first mold part 10 (more specifically, the gap between the projecting pin 50 and the projecting pin insertion hole 53) is C ₁ . Depending on the raw material resin used, it may not be necessary to form the fluid introduction part. Alternatively, the protruding pin 50 and the first
In some cases, it may not be necessary to flow the fluid from the gap between the mold part 10 and the gap (more specifically, the gap between the protruding pin 50 and the protruding pin insertion hole 53).

4 and 5 show the steps of assembling the mold assembly of the present invention.

First, as shown in the schematic partial sectional view of FIG. 4 (A), a portion to which the core 11 is attached (core mounting portion).
The first die part 10 made from S55C is subjected to cutting processing so that the dimension is 105.00 mm × 105.00 mm. Further, the fluid introduction part 51 is engraved in the first mold part 10. Further, a protruding pin insertion hole 52 having a diameter of 4.00 mm is provided in the first mold part 10. The fluid introducing portion 51 communicates with the protruding pin insertion hole 52, and
There is an opening in the core mounting part.

On the other hand, the core 11 made of S55C is manufactured. Core 1 near the top surface of the core 11 for fixing the nest 40
The cross-sectional dimension of 1 was 103.00 × 103.00 mm. In addition, the cross-sectional dimension below the core 11 is 105.00 ×
It was set to 105.00 mm. Then, the nest 40 was fixed to the top surface of the core 11 using an epoxy adhesive. The nest 40 is made of ZrO ₂ —Y ₂ O ₃ and has a thickness of 4.00 m.
m is a flat plate shape of 101.00 mm × 101.00 mm. The cavity surface 41 of the nest 40 was polished with a diamond grindstone, and the surface roughness R _max of the cavity surface 41 of the nest 40 was set to 0.02 μm.

Next, the core 11 was fixed to the first mold part 10 (see the schematic partial sectional view of FIG. 4B). The clearance (D) between the nest mounting portion 12 and the nest 40 is
It is preferably 0.5 mm or more. Here, the clearance (D) refers to a clearance between the nest mounting portion 12 and the nest 40 along the cavity surface 41 of the nest 40. If the value of D is less than 0.5 mm, the resistance becomes large, and it may be difficult for the fluid to flow in the gap between the insert mounting portion 12 and the insert 40. The upper limit of the value of D is not particularly limited, but it is preferably about 10 mm from the viewpoint of the structure and design of the mold. In Example 1, the value of D is 4 mm
And

Next, it is manufactured from S55C so that the clearance (C ₀ ) with respect to the cavity surface 41, which is the surface of the insert 40, is 0.02 mm, and the margin (ΔS) with the end of the insert 40 is 0.5 mm. The first holding plate 42
It was fixed to the mold part 10 with a screw (not shown) (see the schematic partial sectional view of FIG. 5A). It should be noted that the holding plate 42 is provided with a protruding pin insertion hole 53 that matches the protruding pin insertion hole 52 provided in the first mold part 10.

A second mold part 20 was produced from S55C. In the first embodiment, as shown in FIG. 3, a printing basket structure is formed by the end surface (side surface) of the pressing plate 42 attached to the first mold unit 10 and the parting surface of the second mold unit 20. Has been formed.

Finally, the protruding pin 50 is attached to the first die unit 1.
No. 0 protruding pin insertion holes 52 and 53 were inserted to complete the mold assembly (see the schematic partial sectional view of FIG. 5B). The diameter of the protruding pin 50 is 20 mm from the tip.
Was set to 3.98 mm. Therefore, the protruding pin 50
The clearance (C ₁ ) between the first mold part 10 and the first mold part 10 was 0.01 mm. The diameter of the protruding pin 50 at the other portions was set to 3.0 mm.

The shape of the molded product to be molded was a flat plate of 100 mm × 100 mm and a thickness of 4 mm, excluding the peripheral portion.

Even after the completed mold assembly is attached to the injection molding machine and heated to 130 ° C using a mold temperature controller and then rapidly cooled to 40 ° C, the nest 40 is cracked. Did not occur.

An injection molding machine manufactured by Toshiba Machine Co., Ltd.
Using a pre-sterol injection molding machine, 100 mold assembly
Heated to ° C. Further, as a thermoplastic resin which is a raw material resin, polyacetal resin containing 10% by weight of fluororesin (F manufactured by Mitsubishi Engineering Plastics Co., Ltd.
L2010) was used.

First, the first mold part 1 is designed so that the volume of the cavity 31 is larger than the volume of the molded product to be molded.
0 and the second mold part 20 were clamped. Specifically, the thickness t ₀ of the molded product to be molded is 4 mm, and the distance t ₁ of the cavity 31 during mold clamping in the thickness direction of the molded product is 6 mm.
And That is, Δt = t ₁ −t ₀ = 2 mm. This state is shown in the schematic end view of FIG.

Resin temperature 190 ° C., injection pressure 2
Under the condition of 00 kgf / cm ² , the molten resin 60 was injected into the cavity 31 from the injection cylinder (not shown) through the molten resin injection part 30 provided in the second mold part 20. A state immediately before the completion of injection of the molten resin 60 into the cavity 31 is shown in a schematic end view of FIG. 7. Simultaneously with the completion of the injection of the molten resin, the volume of the cavity 31 was started to be reduced, and after the elapse of a predetermined time, the volume of the cavity 31 was reduced to the volume of the molded product to be molded. Specifically, the first mold part 10 was moved and clamped (compressed) until the distance of the cavity 31 in the thickness direction of the molded product became 4 mm.
This state is shown in the schematic end view of FIG. The amount of molten resin injected into the cavity 31 is
When the volume of is reduced to the volume of the molded product to be molded,
The amount is such that the inside of the cavity 31 is completely filled with the molten resin.

After the injection of the molten resin was completed, the resin in the cavity 31 was cooled for 30 seconds, and then the mold was opened. This state is shown in the schematic end view of FIG. Incidentally, in FIG. 9, the illustration of the second mold part 20 is omitted. Next, the molded product 61 was released from the first mold part 10 using the protruding pin 50. This state is shown in the schematic end view of FIG. In Example 1, since the wettability between the used polyacetal resin and the nest 40 was not high, the molded product could be easily separated from the nest 40.
The molded product had a very clean appearance. In addition, no sink mark was generated at the end of the molded product, and the smoothness was excellent.
Although molding was continuously performed for 10,000 shots, the nest 40 did not suffer damage such as cracking.

Example 2 In Example 2, the mold assembly was the same as in Example 1. Further, as the thermoplastic resin which is the raw material resin, unlike the first embodiment, the glass fiber is 1
Polycarbonate resin added with 0% by weight (GS2010M manufactured by Mitsubishi Engineering Plastics Co., Ltd.)
Was used. Resin temperature 300 ° C, injection pressure 200k
The molding conditions were the same as in Example 1 except that gf / cm ² was used.

When a polycarbonate resin is used as the thermoplastic resin, the wettability between the molten resin 60 and the cavity surface 41 of the insert 40 is improved, and as a result, the resin (molded product) and the cavity surface 41 of the insert 40 are improved. A vacuum state is created between them and it becomes extremely difficult to separate the molded product 61 from the insert 40. In order to avoid such a phenomenon, the first
7 kg / cm after opening the mold part 10 and the second mold part
^While flowing a fluid consisting of ^2- G compressed air from a fluid source (not shown) consisting of an air compressor through the fluid introducing portion 51 and through the gap between the projecting pin 50 and the first die portion 10. , At the same time, the first mold part 10 and the core 11
The molded product 61 was released from the first mold part 10 by using the projecting pin 50 while flowing from the gap between the insert 40 and the holding plate 42 via the gap. This state is shown in the schematic end view of FIG.

The molded product 61 is easily separated from the insert 40,
The molded product 61 could be easily released from the first mold part 10.
The glass fiber was not exposed on the surface of the molded product, and the molded product had a very beautiful appearance. In addition, no sink mark was generated at the end of the molded product, and the smoothness was excellent. Although molding was continuously performed for 10,000 shots, the nest 40 did not suffer damage such as cracking.

Comparative Example 1 The thermoplastic resin and mold assembly were the same as in Example 2. Further, the molding conditions are also those of Example 2.
The same conditions were used. Comparative Example 1 is different from Example 2 in that when a molded product is released from the first mold part 10, a gap between the protruding pin 50 and the first mold part 10 and the nest 40 are formed. The point is that the fluid was not made to flow from the gap between the holding plate 42.

As a result, the molded product was firmly attached to the cavity surface 41 of the insert 40, and the molded product did not separate from the insert 40. Therefore, as in the second embodiment, when the fluid flows through the gap between the protrusion pin 50 and the first mold part 10 and the gap between the insert 40 and the restraining plate 42, the protrusion pin 50 is used. As a result, the molded product 61 could be released from the first mold part 10.

Comparative Example 2 In Comparative Example 2, a nest made of Starbucks steel was used, and the cavity surface of the nest was mirror-polished. Except for this point, the same thermoplastic resin and mold assembly as in Example 2 were used, and molding was performed under exactly the same molding conditions as in Example 2.

As a result, in Comparative Example 2, since the nest made of Starbucks steel was used, the wettability between the resin and the cavity surface of the nest was not high, and the protruding pin 50 and the first mold part 10 were Without flowing the fluid through the gap between the first mold portion 10 and the molded product 61 without flowing the fluid through the gap between the mold 40 and the holding plate 42.
Was able to be released. However, the glass fiber was exposed on the surface of the obtained molded product, and it had no gloss and had an ugly appearance.

Comparative Example 3 In Comparative Example 3, Example 2
Mold assembly and thermoplastic resin were used. Comparative Example 3 is different from Example 2 in that Δt = 0 mm. That is, the distance t ₁ between the cavities 31 in the thickness direction of the molded product was set to 4 mm when the first mold part and the second mold part were clamped. The thickness t ₀ of the molded product to be molded is 4 mm. Other molding conditions were the same as in Example 2.

As a result, the injection pressure was 700 kgf / cm.
^If it was not raised to ^2, it was not possible to completely fill the cavity with the molten resin. Although no fibers were exposed on the surface of the obtained molded product, sink marks were generated at the end of the molded product.

The present invention has been described above based on the preferred embodiments, but the present invention is not limited to these.
The structure of the mold assembly, the thermoplastic resin used, and the molding conditions described in the examples are examples, and may be appropriately changed according to the required characteristics and performance of the molded product, the injection molding apparatus used, and the like. it can.

[0069]

By using the mold assembly of the present invention, the molten resin injected into the cavity can be prevented from being rapidly cooled, so that the wettability between the molten resin and the cavity surface of the nest can be improved. It is possible to obtain high transferability, and it is possible to prevent the deposition of fibers and the like depending on the raw material resin used. Moreover, it is possible to easily release the molded product from the mold. Further, by adopting the injection compression molding method, the injection pressure of the molten resin can be set low, and further, the fluidity of the molten resin is improved by using the nest made of ceramic or glass. The injection pressure can be set lower. As a result, the stress remaining in the molded product can be relaxed and the quality of the molded product is improved. Moreover, since the pressure is uniformly applied to the surface of the molded product, it is possible to prevent the occurrence of sink marks which has occurred in conventional injection molding. Further, it is possible to effectively prevent the deformation and damage of the nest.

Depending on the raw material resin used, since the solidified layer develops slowly, the wettability between the molten resin and the surface forming the cavity of the nest is improved, and as a result, the surface forming the cavity of the nest is improved. A vacuum state may be formed between the resin (molded product) and it may be difficult to release the molded product from the mold. In the present invention, a protruding pin is provided, and after the molded product is molded, the mold is opened, and when the molded product is released from the first mold part using the protruding pin, the protruding pin and the first mold part are separated from each other. The structure that allows the fluid to flow from the gap between the nest and the restraint plate prevents the vacuum between the surface that constitutes the cavity of the nest and the resin (molded product), ensuring reliable molding. The article can be released from the first mold part.

[Brief description of drawings]

FIG. 1 is an overall conceptual diagram of a mold assembly of the present invention before mold clamping.

FIG. 2 is an overall conceptual diagram of the mold assembly of the present invention immediately after mold clamping and during resin cooling.

FIG. 3 is a schematic end view of an enlarged mold assembly in the area around the cavity.

FIG. 4 is a schematic partial cross-sectional view of a mold part and the like for explaining a process of assembling the mold assembly according to the first embodiment.

FIG. 5 is a schematic partial cross-sectional view of the mold part and the like for explaining the assembling process of the mold assembly according to the first embodiment, following FIG. 4;

FIG. 6 is a schematic end view of the mold assembly immediately after the mold is clamped in the first embodiment.

FIG. 7 is a schematic end view showing a state immediately before the completion of injection of the molten resin into the cavity in Example 1.

FIG. 8 is a schematic end view showing a state in which a resin in a cavity is being cooled in Example 1.

FIG. 9 is a schematic end view showing a mold open state and a molded product release state in Example 1.

FIG. 10 is a schematic end view showing a released state of a molded product in Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 1st metal mold part 11 Core 12 Nest mounting part 20 2nd metal mold part 30 Molten resin injection part 31 Cavity 40 Nest 41 Cavity surface 42 of a nest 42 Suppression plate 50 Projecting pin 51 Fluid introducing part 52,53 Projecting pin Insertion hole 60 Molten resin 61 Molded product

Claims (6)

[Claims] (A) A mold comprising a first mold part and a second mold part, wherein a cavity for molding a molded product based on a thermoplastic resin is formed inside the mold when the mold is clamped. A mold having a structure capable of varying the volume of the cavity at the time of molding the product; and (b) a part of the cavity which is disposed in the first and / or second mold parts and has a thickness of 0.5 mm to 10 mm
A ceramic mold or glass mold insert, and (c) a mold plate that is attached to the mold part in which the insert mold is arranged, forms a part of a cavity, and suppresses the end part of the mold insert. It is three-dimensional and the clearance between the nest and the restraint plate is 0.0
A mold assembly for injection compression molding, which has a size of 01 to 0.03 mm and a pressing margin of the pressing plate with respect to the insert is 0.1 mm or more. 2. A projection pin disposed slidably in the first mold part, wherein the clearance between the projection pin and the first mold part is 0.01 to 0.03 mm. The gap between the projecting pin and the first mold part, and the gap between the insert and the restraining plate are connected to the fluid source. After molding the molded product, the mold is opened and the projecting pin is used to When releasing the molded product from the first die part, the protruding pin and the first
The fluid can flow from a gap between the mold part of the base plate and a gap between the insert and the holding plate.
A mold assembly for injection compression molding according to item 1. 3. The nest has a thermal conductivity of 2 × 10 ^-2 cal /
or less cm · sec · deg, ceramic consisting ZrO ₂ -Y ₂ O ₃ or 3Al ₂ O ₃ · 2SiO _2, or claim 1 or claim 2, characterized in that it is made of crystallized glass A mold assembly for injection compression molding according to item 1. 4. A mold comprising a first mold part and a second mold part, wherein a cavity for molding a molded product based on a thermoplastic resin is formed inside the mold when the mold is clamped. A mold having a structure capable of varying the volume of the cavity at the time of molding the product; and (b) a part of the cavity which is disposed in the first and / or second mold parts and has a thickness of 0.5 mm to 10 mm
And a nesting plate made of ceramic or glass of (c), and (c) a pressing plate that is attached to the mold part in which the nesting is arranged, forms a part of the cavity, and suppresses the end of the nesting. The clearance between the holding plate and the holding plate is 0.001 to 0.03 mm, and the holding amount of the holding plate with respect to the insert is 0.1 mm.
An injection compression molding method using a mold assembly as described above, comprising: (A) a first mold part and a second mold part such that the volume of the cavity is larger than the volume of the molded product to be molded. A step of clamping the mold part, (B) a step of injecting a molten thermoplastic resin into the cavity, and (C) a start of injection of the thermoplastic resin, at the same time as during injection, or after the completion of injection, A step of reducing the volume of the cavity to a volume of a molded article to be molded, and (D) a step of cooling the thermoplastic resin in the cavity and releasing the obtained molded article from the mold,
An injection compression molding method comprising: 5. The mold assembly further comprises a projecting pin slidably disposed in the first mold section, and the clearance between the projecting pin and the first mold section is 0.01. To 0.0
3 mm, the gap between the protruding pin and the first mold part, and the gap between the insert and the restraining plate are connected to the fluid source, and after the molded product is molded, the mold is opened and the protruding When the molded product is released from the first mold part using the pin, the fluid flows through the gap between the protruding pin and the first mold part and the gap between the nest and the restraining plate. The injection compression molding method according to claim 4. 6. The nest has a thermal conductivity of 2 × 10 ^-2 cal /
or less cm · sec · deg, ceramic consisting ZrO ₂ -Y ₂ O ₃ or 3Al ₂ O ₃ · 2SiO _2, or claim 4 or claim, characterized in that it is made of crystallized glass 5 The injection compression molding method according to.