WO2017208584A1

WO2017208584A1 - Gas extraction method in resin injection molding and shim plate used in said gas extraction method

Info

Publication number: WO2017208584A1
Application number: PCT/JP2017/011914
Authority: WO
Inventors: 俊男荒木; 弘美竹本
Original assignee: タカラ化成工業株式会社
Priority date: 2016-05-30
Filing date: 2017-03-24
Publication date: 2017-12-07
Also published as: JP2017213692A

Abstract

In order to make it possible to perform gas extraction without difficulty even if a "gas extraction point," which has been previously set by placement of a shim plate, is slid, the present invention is a gas extraction method in resin injection molding for extracting gas inside a cavity C₁ during injection molding by disposing shim plates S₁ between the respective mold mating surfaces 1 and 2 of a movable mold (lower mold) F₁a and a fixed mold (upper mold) F₁b, wherein said shim plates S₁ are configured to have one or multiple gas extraction grooves 11 formed on one surface thereof so as to run, when emplaced, from inside the cavity C₁ to the outside of the mold.

Description

Degassing method in resin injection molding and shim plate used in the degassing method

The present invention relates to a degassing method with improved degassing reliability in resin injection molding performed by placing a shim plate between mold-mating surfaces of a movable mold and a fixed mold, and a shim used in the degassing method It is about a board.

As a method of venting the cavity in the resin injection molding, a method of vacuuming the gas, and a minute venting groove having a size that does not allow the molten resin to enter at least one of the mating surfaces of the movable mold and the fixed mold. There is a method, but the former can be surely vented, but there is a problem that the equipment to be used is expensive, and the latter can be easily implemented, but the certainty of venting is low, resulting in defective moldings. There is a problem that is easy to do.

As another degassing method, a shim plate made of a thin metal plate having a plate thickness of 0.07 to 0.10 mm is disposed between the mold combining surfaces of the movable and fixed molds. There is also a method of forming an ultrathin space part for degassing for allowing only the gas in the cavity to be discharged out of the mold without allowing the molten resin to enter the peripheral part of the shim plate on the mold mating surface (patent) Reference 1).

The cavity of the mold is the part of the cavity where the molten resin is the worst, or the part where the molten resin reaches the latest, in relation to the shape of the molded product (cavity) or the position of the gate relative to the cavity, Since the portion where the gas in the cavity is most likely to accumulate is generated and it is most effective to vent the gas from this portion, the portion is referred to as a “degassing point”. Note that the “gas venting point” is a “point” in terms of words, but naturally has a certain width as a range in which gas can be vented.

The shim plate is disposed at a position where the “gas venting point” can be formed on the mold mating surface of each mold, thereby forming an extremely thin gas discharge space in the portion, so that the gas in the cavity is molded. It is discharged outside. As a specific example of the above-mentioned “gas venting point”, for example, as shown in FIGS. 1 and 2 according to the embodiment of the present invention, molten resin is injected from two gates into one cavity, In the cavity, as shown in FIG. 6 and FIG. 7 where the molten resin injected from two different gates merges, in order to form a hole in the molded product, a mold is formed in the cavity. In the case where the protrusions are arranged in a state where the protrusions are inserted, a portion facing the gate with respect to the protrusions of the molding die that the molten resin arrives most late is mentioned.

Then, a “gas venting point” in the cavity is determined, and shim plates are arranged between the

mold joining surfaces

1 and 2 of the molds F ₁₁ a and F ₁₁ b that can form the “gas venting point”. For example, in FIG. 16A, the minute gap between the two shim plates S ′ is the “gas vent point P ₁₁ ”, and in FIG. 16B, any one of the shim plates S ′. One of the side portions is the “gas vent point P ₁₂ ”. When the shim plate S ′ is arranged at a position where a “gas venting point” can be formed, even if the shim plate S ′ is compressed by the clamping force of the mold, the “gas venting point P _{11 with} respect to the shim plate S ′. Since the position of (P ₁₂ ) ”does not shift, there is no problem. However, in each molding, when the “outgassing point” is shifted to the portion where the shim plate S ′ is disposed, the shim plate S ′ itself becomes an obstacle, and the gas in the cavity is effectively removed. May not be discharged. In FIGS. 16 (a) and 16 (b), the “degassing point” shifted to the shim plate S ′ is labeled P ₁₁ ′ (P ₁₂ ′).

That is, when degassing the cavity using a conventional shim plate, the “degassing point” formed by the arrangement of the shim plate matches the “degassing point” in actual resin injection molding. In this case, there is no problem, but if for some reason the “gas venting point” shifts to the shim plate placement position, the shim plate inhibits gas discharge and Not enough. As a result, there is a problem that sinks occur on the surface of the molded product, resulting in molding defects.

FIG. 3 of Japanese Patent Laid-Open No. 7-304090

In order to solve the above-described problems, the present invention has an object to enable gas venting without any trouble even when a “gas vent point” set in advance by the arrangement of shim plates is slid.

In order to solve the above-mentioned problem, the invention of claim 1 is directed to degassing in resin injection molding in which a shim plate is arranged between the mold-matching surfaces of the movable mold and the fixed mold to degas the cavity during injection molding. A method,
One surface of the shim plate is formed with one or more gas venting grooves from the inside of the cavity to the outside of the mold in the arrangement state.

According to the first aspect of the present invention, in the shape of the molded product (cavity) or the relationship of the position of the gate with respect to the cavity, the molten resin is the worst in the cavity or the molten resin reaches the latest. Shim plates are arranged on the mold mating surfaces of the respective molds at the “gas vent point”. Since the shim plate used in the degassing method of the invention of claim 1 is in an arranged state, one or more degassing grooves are formed on one side of the shim plate from the inside of the cavity to the outside of the mold. In the case where the “outgassing point” remains as set, from the minute gap on the side of the shim plate arranged on the mold-matching surface of each mold or the minute gap between two adjacent shim plates, Gas is discharged out of the mold.

On the other hand, if the set “gas release point” is shifted to the shim plate placement side, in the conventional structure, the minute gap of the gas release is completely blocked by the shim plate, and the gas cannot be released. Alternatively, in the invention of claim 1, since one or more degassing grooves are formed on one surface of the shim plate, the degassing groove and the mold-matching surface of one of the opposing molds In the meantime, a minute gap corresponding to the depth of the gas vent groove is formed. The shim plate is compressed and thinned by the clamping force of each mold. Correspondingly, the depth of the degassing groove of the shim plate is reduced (shallow), but is not lost. Therefore, even if the “gas venting point” moves to the shim plate, a minute gap is formed due to the presence of the gas vent groove formed in the shim plate, and the gas in the cavity is released from the mold through the minute gap. It is effectively discharged and does not remain in the cavity. As a result, it is always possible to mold a good product without producing a defective product even if sinks occur in the “gas venting point” portion on the surface of the injection molded product.

In addition, because the gas in the cavity is discharged out of the mold through the gas vent groove formed in the shim plate, the shim plate can be made thinner compared to the conventional gas venting method using the shim plate, The minute gap formed between the die mating surfaces of the respective molds can be further reduced. As a result, it is possible to more reliably prevent the occurrence of burrs caused by the molten resin entering the minute gaps.

According to a second aspect of the present invention, in the first aspect of the present invention, a gas vent communicating with the outside of the mold is formed on the anti-cavity side of the shim plate on the mating surface of either the movable mold or the fixed mold. The gas that has passed through the gas vent groove of the plate is discharged out of the mold through the gas vent.

According to the invention of claim 2, since the gas vent communicating with the outside of the mold is formed on the anti-cavity side of the shim plate on the mold mating surface of both molds, The gas staying in the portion passes through the gas vent groove provided in the shim plate or the minute gap between the mold-matching surfaces on at least one side of the shim plate, and then enters the anti-cavity side of the shim plate. Since it is discharged out of the mold through the formed gas vent, the gas is smoothly discharged.

Invention of Claim 3 is the shim board used for the degassing method in the resin injection molding of

Claim

1 or 2,
One or a plurality of gas venting grooves are formed on one surface of the shim plate from the cavity of the molding die to the outside of the die in an arranged state.

The invention of claim 3 defines the degassing method in the resin injection molding of the invention of

claim

1 or 2 from the surface of the shim plate used in the degassing method, and the effect is This is equivalent to the first invention.

The invention of claim 4 is characterized in that, in the invention of claim 3, the gas vent groove of the shim plate is formed by etching.

Since the thickness of the shim plate is 0.05 to 0.70 mm, it is difficult to form a vent groove on the surface by the method by mechanical cutting, but the etching process according to the invention of claim 4 Thus, by masking the portions other than the portion for forming the gas vent groove, only the exposed portion for forming the gas vent groove is dissolved by the chemical, so that it can be formed relatively easily.

The invention of claim 5 is the invention of claim 3 or 4, wherein the shim plate has a thickness of 0.05 to 0.70 mm, and the width of the straight vent groove and the formation pitch are respectively It is characterized by 0.4 to 1.5 mm and 1.5 to 3.0 mm.

As in the invention of claim 5, if the thickness of the shim plate is 0.05 to 0.70 mm, the gas in the cavity can be discharged. In particular, in order to form a gas vent groove on one surface of the shim plate by etching or the like, the width of the gas vent groove is 0.4 to 1.5 mm, and the formation pitch is 1.5 to 3.0 mm. If it exists, the shape of a gas vent groove can be formed, and the function as a gas vent groove can be achieved in a state where the gas vent groove is disposed on the die mating surface of each mold.

The invention of claim 6 is characterized in that, in the invention of claim 5, the depth of the gas vent groove of the shim plate is 0.01 to 0.62 mm.

When the thickness of the shim plate is 0.05 to 0.70 mm, the depth of the gas vent groove is preferably 0.01 to 0.62 mm as in the invention of claim 6. If the depth of the gas vent groove is 0.01 to 0.62 mm, even if the shim plate is compressed by the clamping force of both molds, the gas vent groove remains and can perform the gas venting action.

According to the present invention, in a state where the shim plate according to the present invention is disposed between the mold matching surfaces of each mold so that a “gas venting point” is formed at a set position of each mold. Even when the “gas venting point” is shifted to the arrangement portion of the shim plate, in the present invention, one or a plurality of gas venting grooves are formed on one surface of the shim plate. A minute gap corresponding to the depth of the gas vent groove is formed between the mold mating surfaces of the mold. The shim plate is compressed and thinned by the clamping force of each mold. Correspondingly, the depth of the degassing groove of the shim plate is reduced (shallow), but it is not lost. Even if the “punch point” moves to the shim plate, a minute gap is formed due to the presence of the gas vent groove formed in the shim plate, and the gas in the cavity is effectively discharged out of the mold from the minute gap. And will not remain in the cavity. As a result, it is always possible to mold a good product without producing a defective product even if sinks occur in the “gas venting point” portion on the surface of the injection molded product.

FIG. 2 is a perspective view of a rectangular plate-shaped molded product A ₁ and its molding die F ₁ . It is a plan view of the lower mold F ₁ a mold F _1. According to the present invention is a perspective view of the elongated shim plate S _0. It is an enlarged sectional view of the shim plate S ₁ of rectangular shape. Each type F ₁ a of the upper and lower, which is an enlarged sectional view of a portion shim plate S ₁ is disposed between the mold face 2 of the F ₁ b. Molded article A ₂ having a hole 13 in the bottom plate portion, and is a perspective view of the mold F _2. (A), (b) is a plan view of the lower mold F ₂ a constituting the mold F _2, respectively, and a cross-sectional view of the mold F _2. FIG. _{3 is} a perspective view of two-piece molded products A ₃₁ and A ₃₂ and a molding die F ₃ thereof. Is a plan view of the lower mold F ₃ a of the mold F ₃ showing the arrangement of the shim plate S _1. It is a perspective view of a molded article A ₄ and the mold F _4. (A), (b) is a plan view of the lower mold F ₄ a of each mold F _4, and a cross-sectional view of a mold F _4. It is a perspective view of a molded article A ₅ and its mold F _5. (A), (b) is a plan view of the lower mold F ₅ a respective mold F _5, and a cross-sectional view of a mold F _5. (A) is a plan view of the lower mold F ₁ a (F ₂ a to F ₅ a) showing the arrangement of the shim plate S ₁ and the first and second gas vents 31 and 32, and (b) 2A is a sectional view taken along line XX in FIG. (A) to (c) are schematic plan views showing straight intersecting and curved degassing grooves 11 ', 11 ", 11'". (A), (b) is a schematic cross-sectional view showing that when the conventional shim plate S ′ is used, the “gas vent points P ₁₁ , P ₁₂ ” are shifted and gas venting cannot be performed effectively. It is.

Hereinafter, the present invention will be described in more detail with reference to a plurality of optimum embodiments.

FIG. 1 and FIG. 2 show a molding die F _{1 of} Example 1 to which the present invention is applied. FIG. 1 is a diagram showing a rectangular plate-shaped molding A ₁ and its molding die F ₁ . FIG. 2 is a view showing a state in which a plurality of square shim plates S ₁ are arranged on the die mating surface 1 of the lower die F ₁ a constituting the forming die F ₁ . Each type F ₁ a of the upper and lower, cavities C ₁ hollow rectangular plate shape is formed by F ₁ b, the one of the cavities C _1, 2 one with a predetermined interval along the longitudinal direction of the cavity C ₁ molten resin is injected from the gate G _1. In the upper mold F ₁ b, a sprue E ₁ connected to an injection molding machine (not shown) is formed perpendicular to the mold matching surface 2 of the upper mold F ₁ b, and each mold F ₁ a, the F ₁ b mold face 2 of the sprue E ₁ and runner R ₁ for connecting two of said gate G ₁ is formed. In the mold F ₁ , the lower mold F ₁ a is a movable mold, and the upper mold F ₁ b is a fixed mold. Regarding the sign of the mold face 2, including the mold F _1, all of the mold F ₁ ~ F ₅ described later, using the same reference numerals.

In a hollow rectangular plate shape of the cavity C ₁ in which two molten resin from the gate G ₁ is emitted, the longitudinal ends, be between two gates G _1, moreover opposing portion in the lateral direction (this In the total of four portions, which are the molten resin merging portions 12 from different directions between the opposing portions), the arrival of the molten resin is most delayed, so that the gas generated in the cavity C ₁ tends to accumulate Shim plate between the

mold matching surfaces

1 and 2 of the upper and lower molds F ₁ a and F ₁ b because it is a portion that becomes a “punch point (P ₁ a, P ₁ b, P ₁ c, P ₁ d)”. S ₁ is disposed, and gas in the cavity C ₁ is generated from the minute gap 3 between the

mold joining surfaces

1 and 2 of the molds F ₁ a and F ₁ b corresponding to the thickness T of the shim plate S _1. ing. The minute gap 3 has a space thickness where the molten resin cannot enter.

As shown in FIGS. 3 and 4, the long shim plate material S ₀ is formed into a long plate shape with a thin stainless plate, for example, and its thickness T is 0.05 to 0.70 mm. The width K is arbitrary, but commercially available ones are often 12.7 mm. The long plate-shaped long shim plate material S ₀ is wound and stored in a cylindrical shape, is unwound during use, and is cut into a square having an appropriate size for use.

On one surface of the long shim plate S ₀ , a large number of gas vent grooves 11 are formed at a predetermined pitch Q along the width direction. The width W and depth D of the gas vent groove 11 are 0.4 to 1.5 mm and 0.01 to 0.62 mm, respectively. The depth D of the gas release groove 11 can be made deeper in proportion to the thickness T of the shim plate S _1. Since the thickness T of the shim plate S ₁ is as thin as 0.05 to 0.70 mm, it is difficult to form the gas vent groove 11 on the surface of the shim plate S ₁ by a mechanical cutting method. It can be formed relatively easily by masking the portions other than the portion and dissolving only the exposed degassing groove forming portion with chemicals (chemical cutting). The reason why the width W of the gas vent groove 11 is set to 0.4 to 1.5 mm is within a range in which the function as the gas vent groove 11 can be achieved and the above-described etching process can be performed. It is about 5 mm. Further, the depth D of the gas vent groove 11 is 0.01 to 0.62 mm. If the depth D of the gas vent groove 11 is less than 0.01 mm, the function as the gas vent groove 11 cannot be achieved. Considering that the plate thickness T of the plate S ₁ is 0.05 to 0.70 mm, even when the plate thickness T is 0.70 mm, the depth D of the gas vent groove 11 exceeds 0.62 mm. This is because a part of the gas vent groove 11 is exposed on the back surface and the shim plate S ₁ may be damaged.

The shim plate S ₁ is obtained by cutting the long shim plate material S ₀ into a square shape, and the above-mentioned “gas venting points (P ₁ a, P ₁ b, P ₁ c) on the die mating surface 1 of the lower die F ₁ a. , P ₁ d) ”is attached using a double-sided tape or an adhesive.

Then, there are two possible methods for arranging the shim plate S ₁ for each part of the above-mentioned “gas venting points (P ₁ a, P ₁ b, P ₁ c, P ₁ d)”. For example, as shown in FIG. 1 and FIG. 2, the shim plate S ₁ is disposed on the position of “gas venting points (P ₁ a, P ₁ b, P ₁ c, P ₁ d)”. are those (hereinafter, referred to as "first shim plate arrangement method"), the other one, as in the method of arranging the conventional shim plate S ', by disposing the shim plate S _1, the side Are defined as “gas venting points” (hereinafter referred to as “second shim plate arrangement method”). As described above, in many times of injection molding, although the molten resin melting path has a certain regularity, it is not always the same path, so the position of the “gas vent point” itself includes its width. All are not strictly fixed positions and may be displaced.

Here, the shim plate S ₁ is compressed and thinned by the clamping force of the upper and lower molds F ₁ a and F ₁ b constituting the molding die F ₁ , but the gas formed on the shim plate S ₁ The draft groove 11 remains in a state where the depth D is somewhat shallower and does not disappear. In addition, regarding the display of the shim plate S ₁ having a plurality of gas vent grooves 11 arranged on the mold mating surface 1 of the lower molds F ₁ a to F ₅ a, all except for FIGS. It is schematically shown by ignoring the number of the cutout grooves 11.

Therefore, in the former “first shim plate arrangement method”, “gas venting points (P ₁ a, P ₁ b, P ₁ c, P ₁ d)” exist on the arrangement position of the shim plate S _1. , if at the time of molding and setting time of the "venting point" matched, gas generated in the cavity C _1, the type of the plurality of gas release groove 11 formed in the shim plate S ₁ as the main discharge path In addition to being discharged outside, it is also discharged out of the mold through the minute gaps 3 between the upper and lower molds F ₁ a, F ₁ b formed on both sides of the shim plate S _1. Is done.

On the other hand, in the latter “second shim plate arrangement method”, when the “gas venting point” at the time of setting and molding match, the gas generated in the cavity C ₁ uses the conventional shim plate S ′. As in the case of the case, the minute gap 3 on at least one side of the shim plate S ₁ becomes the “gas release point”, the gas in the cavity is discharged out of the mold, and the “gas release point” at the time of setting is when shifted to the portion of the shim plate S ₁ passes through the plurality of gas release groove 11 formed on the shim plate S _1, the gas in the cavity is discharged out of the mold.

Therefore, when the shim plate S _{1 according} to the present invention is used by any of the first and second shim plate arrangement methods, even if the preset “gas release point” is shifted, The generated gas can be discharged out of the mold without hindrance.

In Example 1, if the sum of the gates of the molten resin injected into the cavity C ₁ is “2”, the sum of the gates is “3” or “3” or more depending on the shape of the molded product. Even in this case, in consideration of the flow of the molten resin, the shim plate is disposed at a portion where the arrival of the molten resin is most delayed.

Next, with reference to FIGS. 6 and 7, it will be described mold F ₂ of Example 2 according to the present invention. FIG. 6 is a perspective view of a molded product A ₂ having a hole 13 in the bottom plate portion and a molding die F ₂ thereof, and FIGS. 7A and 7B are lower molds constituting the molding die F ₂ , respectively. plan view of the F ₂ a, and a cross-sectional view of the mold F _2. The molded product A ₂ has a three-dimensional shape in which a circular hole 13 is formed at the center of the bottom plate portion of a rectangular box having an open top surface.

Mold F ₂ is the upper mold F ₂ b having a lower mold F ₂ a having a shaped protrusion 21 which corresponds to the internal three-dimensional shape of the molded article A _2, a recess 22 corresponding to the external three-dimensional shape of the molded article A ₂ Further, a circular portion for forming the hole 13 of the molded product A ₂ is formed at each central portion of the upper surface of the convex portion 21 of the lower mold F ₂ a and the bottom surface of the concave portion 22 of the upper mold F ₂ b. A fitting convex portion 23 and a fitting concave portion 24 are formed, and a space formed by matching the upper and lower molds F ₂ a and F ₂ b is a cavity C ₂ . The upper mold F ₂ b is formed with a sprue E ₂ connected to an injection molding machine (not shown), and a connecting portion between the sprue E ₂ and the cavity C ₂ is a gate G ₂ . The gate G ₂ is arranged at the center in the longitudinal direction of the cavity C ₂ so as to correspond to the arrangement position of the fitting convex portion 23 along the longitudinal direction of the hollow rectangular box-shaped cavity C _2. Yes.

Therefore, the molten resin injected from the gate G ₂ into the cavity C ₂ is obstructed against the flow by the fitting convex portion 23 formed in the lower mold F ₂ a, so that the molten resin reaches the cavity C ₂ . There most delayed sites, as shown in FIGS. 6 and FIG. 7 (a), the opposite point (the point between the gate G ₂ with respect to the fitting convex portion 23, each of the opposite sides of the fitting convex portion 23 And in a plan view, the two corner portions farthest from the gate G ₂ in the cavity C ₂ are a total of three locations, and the mold surface 1 on the lower mold F ₂ a Shim plates S ₁ are arranged at portions corresponding to the three places, and each arrangement portion of the shim plate S ₁ is a “gas venting point (P ₂ a, P ₂ b, P ₂ c)”.

The degassing action of the shim plate S ₁ provided with the degassing groove 11 is the same as that of the molding die F _{1 of the} first embodiment. In both the first and second shim plate arrangement methods, the “gas” position of the punching point "is, if left setting, and be either when shifted from the set time, the gas generated in the cavity C ₂ without staying in the cavity C _2, type Effectively discharged outside.

Next, with reference to FIGS. 8 and 9, it will be described mold F ₃ of the third embodiment according to the present invention. FIG. 8 is a perspective view of the two-piece molded products A ₃₁ and A ₃₂ and the molding die F ₃ thereof, and FIG. 9 is a perspective view of the lower mold F ₃ a of the molding die F ₃ showing the arrangement of the shim plate S ₁ . It is a top view. The molding die F ₃ takes two rectangular thick plate shaped molded products A ₃₁ and A ₃₂ having different shapes, and includes a lower die F ₃ a and an upper die F ₃ b. By combining the upper and lower molds F ₃ a and F ₃ b, hollow cavities C ₃ a and C ₃ b corresponding to the shapes of the molded products A ₃₁ and A ₃₂ are formed, and the upper mold F ₃ b The sprue E ₃ is connected to the runners R ₃ formed on the upper and lower molds F ₃ a and F ₃ b, and both ends of the runners R ₃ are formed in the cavities C ₃ a and C ₃ b. Connected to the gates G ₃ a and G ₃ b. One molded product A ₃₁ has a square shape, but the other molded product A ₃₂ has an irregular square shape in which a protruding portion is formed at one location of a total of four corner portions.

The part where the arrival of the molten resin in the cavity C ₃ is most delayed is the part where the gates G ₃ a and G ₃ b are farthest apart from each other, and on the opposite side of the injection direction of the molten resin from the gate G ₃ b As shown in FIGS. 8 and 9, shim plates S ₁ are arranged at the respective portions of the above-mentioned four locations on the mold-matching surface 1 of the lower die F ₃ a, as shown in FIGS. The arrangement portions of the shim plate S ₁ are “degassing points (P ₃ a, P ₃ b, P ₃ c, P ₃ d)”, respectively.

Next, with reference to FIGS. 10 and 11, will be described mold F ₄ of Example 4 according to the present invention. FIG. 10 is a perspective view of the molded product A ₄ and its molding die F _4. FIGS. 11A and 11B are a plan view of the lower die F ₄ a of the molding die F _{4 and} the molding die F, respectively. it is a cross-sectional view of a _4. In the molded product A ₄ ,

flange portions

42 a and 42 b are formed in the opening of the rectangular box body 41, and the width of the flange portion 42 b formed in one short piece is far greater than the width of the remaining flange portion 42 a. Wide shape.

The lower mold F ₄ a of the molding die F ₄ is formed with a convex portion 25 that forms the internal space of the box body 41, and the upper mold F ₄ b is formed with a concave portion 26 that forms the outer shape of the box main body 41. In addition, a flange recess portion 27 for forming the

flange portions

42a and 42b is formed around the recess portion 26, and the upper and lower molds F ₄ a and F ₄ b are aligned with each other. the recess 26 of the mold F ₄ b, in a state that has entered the projection 25 of the lower mold F ₄ a, each type F ₄ a, a space formed between the F ₄ b has a cavity C _4.

Since the gate G ₄ is arranged at the center of the concave portion 26 of the upper mold F ₄ b, the portion where the arrival of the molten resin in the cavity C ₄ is most delayed is opposed to each short piece of the box body 41 of the molded product A ₄ . each flange portion 42a formed Te is a portion 42b is formed, in the respective parts, the shim plate S ₁ of each rectangular shape is arranged. The arrangement portion of each shim plate S ₁ is “gas venting point (P ₄ a, P ₄ b)”. Since the shim plate S ₁ having a plurality of gas vent grooves 11 is used, even if the “gas vent points (P ₄ a, P ₄ b)” are shifted, the gas generated in the cavity C ₄ is not generated. The effect | action discharged | emitted out of a type | mold without trouble is the same as the above. 10 and 11, E ₄ indicates a sprue connected to the injection molding machine.

Next, with reference to FIGS. 12 and 13, will be described mold F ₅ Example 5 according to the present invention. FIG. 12 is a perspective view of the molded product A ₅ and its mold F _5. FIGS. 13A and 13B are a plan view of the lower mold F ₅ a of the mold F _{5 and} the mold F, respectively. ₅ is a cross-sectional view of. Molded article A ₅ represents, a conical tubular shape symmetrical with respect to the center line, the lower mold F ₅ a and the upper mold F ₅ b of the mold F _5, inner surface shape and the outer surface of each molded article A ₅ A space formed between the molds F ₅ a and F ₅ b is formed in the cavity C ₅ in a state in which the convex part 28 and the concave part 29 for forming the shape are formed and the molds F ₅ a and F ₅ b are combined. It becomes. The upper mold F ₅ b is formed with a sprue E ₅ and a gate G ₅ connected to the center of the small-diameter hollow portion of the cavity C ₅ .

Unlike the cavities C ₁ to C _{4 of} the respective molds F ₁ to F ₄ , the molten resin injected from the gate G ₅ into the cavity C ₅ arrives in the same state in the circumferential direction of the cavity C _5. and, since no specific site where arrival of the molten resin is delayed there, the cavity C in the portion corresponding to the specific site _5, the cavity C ₅ facing the shim plate S ₂ only sides are formed in an arc shape to Without disposing a plurality of pieces (in the embodiment, 4 pieces in each part corresponding to a plurality of parts at equal intervals along the circumferential direction of the cavity C ₅ in the die mating surface 1 of the lower mold F ₅ a). Each of the above-mentioned molds is that the shim plate S ₂ is disposed and the cavity C ₅ side of the shim plate S ₂ is formed in an arc shape corresponding to the shape of the cavity C _5. Different from F ₁ to F ₄ . A portion where each shim plate S ₂ is arranged becomes a “gas venting point (P ₅ a to P ₅ d)”. Since the long shim plate material S ₀ can be cut into an arbitrary shape, the shim plate S ₂ having only one side having an arc shape can be easily formed.

In the mold F _5, a plurality of gas release groove 11 without formed in the small gap 3 and the respective shim plate S ₂ on both sides of the shim plate S ₂ the gas from staying in a specific portion of the cavity C ₅ through, in each portion along the circumferential direction of the cavity C _5, the gas in the cavity C ₅ substantially uniformly is discharged to the outside of the mold.

As described above, in the first to fifth embodiments, the arrangement examples of the shim plates S ₁ and S ₂ have been described. However, depending on the position of the conventional shim plate S ′, a mold that can be vented is used. Of course, the present invention can also be applied to molds other than the above-described molds F ₁ to F ₅ .

FIG. 14A is a plan view of the lower mold F ₁ a (F ₂ a to F ₅ a) showing the arrangement of the square shim plate S ₁ and the gas vents 31 and 32. FIG. 3 is a sectional view taken along line XX of FIG. Thickness T of the shim plate S _1, it is necessary to be able to prevent intrusion of melted resin into the minute gap 3 formed between the upper and lower mold face 2 of each type, moreover, the shim plate S ₁ is In general, the minute gap 3 becomes considerably small because the compression is performed by the clamping force of both molds, and the gas that has passed through the gas vent groove 11 formed in the shim plate S ₁ is released to the outside of the mold. There is a risk that it will not be discharged smoothly. Therefore, as shown in FIG. 14, the length of the shim plate S ₁ corresponds to the side opposite to the cavity of the shim plate S _{1 on} the die mating surface 1 of the lower die F ₁ a (F ₂ a to F ₅ a). If it is a first gas vent 31 along the length direction of the shim plate S _1, by forming the said central portion of the first gas vent 31, and a second gas vent 32 for communicating the mold out, Sim The gas that has passed through the gas vent groove 11 of the plate S ₁ passes through the first and second gas vents 31 and 32 and is smoothly discharged out of the mold. As described above, according to the present invention, the use of the shim plate S ₁ provided with the gas vent groove 11 has an advantage that a gas vent may be formed only in the arrangement portion of the shim plate S ₁ .

In the first to fifth embodiments, the shape of the gas vent groove provided in each of the shim plates S ₁ and S ₂ is a straight line having the smallest gas passage resistance. ), The straight gas vent grooves 11 ′ and 11 ″ may be crossed, and as shown in FIG. The shape may be any.

Further, the side of the shim plate facing the cavity needs to correspond to the shape of the cavity, but when cutting an extremely thin long shim plate material like the shim plate S ₂ used in the fifth embodiment. Any shape shim plate can be formed.

A ₁ to A ₅ : Molded product C ₁ to C ₅ : Cavity D: Depth of gas vent groove E ₁ to E ₅ : Sprue F ₁ to F ₅ : Mold Die F ₁ a to F ₅ a: Under mold Die Molds F ₁ b to F ₅ b: Upper mold of the mold G ₁ to G ₅ : Gates P ₁ to P ₅ : Gas vent point Q: Pitch of the gas vent groove of the shim plate S ₀ : Long shim plate material S ₁ , S ₂ : Shim plate T: Shim plate thickness W: Degassing groove width 1: Lower mold mating surface 2: Upper mold mating surface 3: Micro gap 11 formed between mold mating surfaces, 11 ′, 11 ″, 11 ″ ′: Degassing grooves formed in shim plate 12, 14: Merged portion of molten resin

Claims

A degassing method in resin injection molding in which a shim plate is disposed between each mold-matching surface of a movable mold and a fixed mold, and degassing the cavity during injection molding,
A degassing method in resin injection molding, wherein one or a plurality of degassing grooves are formed on one surface of the shim plate in an arranged state from the inside of the cavity to the outside of the mold.
A gas vent communicating with the outside of the mold is formed on the anticavity side of the shim plate on either the movable mold or the fixed mold mating surface, and the gas that has passed through the gas vent groove of the shim plate passes through the gas vent. 2. The gas venting method in resin injection molding according to claim 1, wherein the gas is discharged out of the mold.
A shim plate used in a gas venting method in resin injection molding according to claim 1 or 2,
One or more degassing grooves are formed on one surface of the shim plate from the mold cavity toward the outside of the mold in an arranged state, and used for a degassing method in resin injection molding. Shim board.
4. The shim plate used in a gas venting method in resin injection molding according to claim 3, wherein the gas vent groove of the shim plate is formed by etching.
The thickness of the shim plate is 0.05 to 0.70 mm, the width of the straight gas vent groove and the formation pitch are 0.4 to 1.5 mm and 1.5 to 3.0 mm, respectively. The shim plate used for the degassing method in the resin injection molding according to claim 3 or 4, wherein the shim plate is used.
The shim plate used for the degassing method in resin injection molding according to claim 5, wherein the depth of the degassing groove of the shim plate is 0.01 to 0.62 mm.