JP2005186356A - Injection molding mold, seal ring manufacturing method using the same and seal ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding mold causing no flash in a gate mark and not bringing about the clogging of a gate in the injection molding of an engineering plastic using a submarine gate, and to provide a seal ring manufacturing method using the mold and the seal ring. <P>SOLUTION: This mold is used for injection-molding a synthetic resin with a heat-resistant temperature of 110°C or above and is equipped with a fixed template, the movable template mated with the fixed template to form a cavity and the submarine gate connected to the cavity. The submarine gate has a columnar shape and the connection width in the cross section of the connection part of the submarine gate and the cavity is smaller than the column diameter of the submarine gate and inclined at an angle of 5-20° with respect to the submarine gate connection surface of the cavity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an injection mold having a submarine gate, a method for manufacturing a seal ring using the mold, and a seal ring.

A submarine gate in injection molding is configured so as to sink from a parting line surface (hereinafter referred to as “PL surface”). This submarine gate automatically cuts and separates the molded body and runner in the mold during the mold opening process or molded product extrusion process, eliminating the need for a gate cut process after molding and shortening the manufacturing process. Conventionally, it is used for achieving the above.
A conventional submarine gate will be described with reference to FIG. FIG. 5 shows a cross-sectional view around the gate opening of the injection mold.
The shape of the gate 13 is a conical shape having a gate port 13a that is a connecting portion with the cavity 14 as a top portion, and is tapered toward the cavity 14 as shown in FIG. The area S ₃ of the gate opening 13a, is compared with the cross-sectional area S ₄ of the gate near the tip portion 13b, both surfaces is circular, because it is attached to the cavity 14 by the gate 13 is inclined, toward the gate opening 13a Has a large diameter and a large area. Further, the angle θ ₁ is an acute angle, and the angle θ ₂ is an obtuse angle.
Since the conventional submarine gate has an undercut at the gate portion, there is a problem in that when the gate is cut, the resin of the gate portion is forcibly removed and the die is worn and the life is shortened. Further, since the area S _{3 of the} gate opening is larger than the cross-sectional area S _{4 in the} vicinity of the gate tip, the resin in the gate portion may be damaged not in the gate opening but in the vicinity of the tip. Due to this breakage, there are burrs on the gate trace of the product, and if a broken piece (cold slug) is mixed into the product at the next injection, there is a problem in quality such as a decrease in mechanical strength of the portion.

In order to cope with such a problem, a molding die is provided to reduce the load applied to the gate portion by smoothly deforming the runner when the gate is cut by providing a pin across a part of the runner (see Patent Document 4). A molding die (see Patent Document 5) that blows compressed air onto the gate portion to prevent cold slug from entering, and a flat surface is provided on the gate portion side so that the minimum cross-sectional area of the submarine gate appears at the gate opening. Mold for preventing chipping (see Patent Document 3), Mold for preventing chipping during gate cutting by making the angle θ ₁ and angle θ ₂ of the connecting surface between the submarine gate and the cavity both acute (patent) Reference 2).
On the other hand, as a functional product manufactured using a submarine gate, a seal ring for preventing leakage of a fluid such as oil or water, or a fluid such as air or other gas is known. An injection molding device that supplies resin to the cavity through a guide hole that communicates with the side wall surface of the cavity by using a submarine gate in order to prevent gate marks from remaining on the functionally important outer peripheral surface of the seal ring. (See Patent Document 1).

However, although the molding die of Patent Document 4 can smoothly extract the runner from the die, it is difficult to prevent the generation of burrs on the gate trace. Furthermore, when a resin material containing a large amount of an inorganic filler or reinforcing material is used, the runner breaks at the slit and it is difficult to smoothly extract the runner from the mold.
Further, the molding die disclosed in Patent Document 5 can prevent cold slug from being mixed in, but does not prevent the generation of burrs on the gate trace, and the die structure is complicated. Furthermore, since a part of the mold is cooled by blowing compressed air and temperature unevenness occurs in the cavity, it is necessary to delay the molding cycle.
In addition, although the molding die of Patent Document 3 can be expected to prevent the generation of burrs on the gate trace, the molding process becomes complicated, and it can be used for small molded products and precision molded products where the gate becomes small. Have difficulty.
In addition, the molding die disclosed in Patent Document 2 can prevent the generation of burrs on gate marks in general-purpose plastics, but it is difficult to prevent the generation of burrs on gate marks when using engineering plastics (engineering plastics). become. When engineering plastics are used, it is difficult to smoothly remove the runner from the mold, and the runner may be damaged.
Further, in the injection molding apparatus disclosed in Patent Document 1, a gate mark is not generated in the seal ring, but mixing of cold slug is unavoidable. Also, special equipment must be attached to the mold and injection molding equipment.
JP-A-9-94851 (paragraph [0035]) Japanese Utility Model Publication No. 5-35241 (paragraph [0019]) Japanese Utility Model Publication No. 3-46895 (page 4, right column, lines 27-38) JP-A-9-193169 (paragraph [0020]) Japanese Utility Model Publication No. 1-1018 (Scope of Claim for Utility Model Registration)

  The problem to be solved by the present invention is that, in the injection molding of engineering plastics using a submarine gate, burrs are generated in the gate trace, the gate is clogged, and the like. An object of the present invention is to provide an injection mold that eliminates these problems, a method of manufacturing a seal ring using the mold, and a seal ring.

The injection mold according to the present invention is an injection mold used when injection molding a synthetic resin having a heat resistant temperature of 110 ° C. or more. The injection mold is abutted against the fixed side mold plate and the cavity to form a cavity. A movable side mold plate to be formed and a submarine gate connected to the cavity, the submarine gate has a cylindrical shape, and the connection width in the cross section of the connection between the submarine gate and the cavity is smaller than the gate cylinder diameter; The cavity is inclined at an angle of 5 to 20 ° with respect to the submarine gate connection surface of the cavity.
The synthetic resin is a synthetic resin composition containing 5% by volume or more of a filler harder than the base resin.
The synthetic resin has a tensile strength of 50 Mpa or more and a tensile elongation of 20% or less.

  The seal ring manufacturing method of the present invention includes a mold closing step in which a fixed mold plate and a movable mold plate are brought into contact to form a cavity, and a molten resin is injected into the cavity from a submarine gate connected to the cavity. A sealing ring manufacturing method comprising a resin filling step of filling, and a molded product ejection step of ejecting a molded product after molding, wherein the submarine gate has a cylindrical shape, and a cross section of a connecting portion between the submarine gate and the cavity The connection width of the submarine gate is smaller than the gate cylinder diameter, and the resin in the submarine gate portion is cut from the molded product at the submarine gate connection surface of the cavity in the molded product ejection step.

  The resin seal ring of the present invention is manufactured by injection molding, and the injection molding process is coupled to the cavity by a mold closing process in which a fixed side mold plate and a movable side mold plate are brought into contact with each other to form a cavity. A resin filling step in which molten resin is injected and filled into the cavity from the submarine gate, and a molded product ejecting step for ejecting the molded product after molding, the submarine gate having a cylindrical shape, and having a submarine gate and cavity The connecting width in the cross section of the connecting portion is smaller than the gate cylinder diameter, and the resin in the submarine gate portion is cut from the molded product at the submarine gate connecting surface of the cavity in the molded product ejecting step.

The injection mold according to the present invention is an injection mold used when injection molding a synthetic resin having a heat resistant temperature of 110 ° C. or more. The injection mold is abutted against the fixed side mold plate and the cavity to form a cavity. A movable side mold plate to be formed and a submarine gate connected to the cavity, the submarine gate is cylindrical, and its connection width in the cross section of the connection between the submarine gate and the cavity is smaller than the gate cylinder diameter. Even when engineering plastics are used, when the molded product is ejected, the resin other than the connecting surface is not easily broken, and burrs are not generated in the gate trace. Therefore, it is possible to prevent cold slug from being mixed into the molded product.
Also, since the submarine gate is inclined 5 to 20 ° with respect to the submarine gate connection surface of the cavity, the resin removal of the gate part at the time of extrusion is not forced and the resin breaks at that part. Can be prevented. Moreover, there is little abrasion of a gate part and the lifetime reduction of a metal mold | die can be suppressed.
Moreover, even when the synthetic resin uses a synthetic resin composition containing 5% by volume or more of a harder filler than the base resin, it is possible to suppress a decrease in mold life.
Further, even when a synthetic resin having a tensile strength of 50 Mpa or more and a tensile elongation of 20% or less is used, the resin is unlikely to break at a portion other than the connection surface.

  The seal ring manufacturing method of the present invention includes a mold closing step in which a fixed mold plate and a movable mold plate are brought into contact to form a cavity, and a molten resin is injected into the cavity from a submarine gate connected to the cavity. A sealing ring manufacturing method comprising a resin filling step of filling, and a molded product ejection step of ejecting a molded product after molding, wherein the submarine gate has a cylindrical shape, and a cross section of a connecting portion between the submarine gate and the cavity The connection width of the submarine gate is smaller than the gate cylinder diameter, and the resin in the submarine gate part is cut from the molded product at the submarine gate connection surface of the cavity in the molding product extrusion step. In this case, the resin is hardly broken at the gate, and no burrs are generated on the gate mark. Therefore, it is possible to prevent cold slug from being mixed into the molded product.

  Since the resin seal ring of the present invention is a seal ring manufactured by the method using the mold described above, the manufacturing process can be simplified because there are no burrs in the gate traces and no mixing of cold slugs. , The quality is stable.

An injection mold according to the present invention will be described with reference to FIG. FIG. 1 shows a sectional view around a cavity of an injection mold.
The injection mold 1 includes a fixed-side mold plate 2, a movable-side mold plate 3 that abuts with the fixed-side mold plate 2 to form a cavity 4, and a columnar submarine gate 7 ( (Hereinafter simply referred to as “gate 7”). Further, the fixed side mold plate 2 is provided with a part of the sprue 5 and the runner 6, and the movable side mold plate 3 is provided with the other part of the runner 6. When the mold shown in FIG. A runner 6 connected to the sprue 5 and a gate 7 connected to the runner 6 form a passage of molding material. Further, 4a is a formation surface of the outer peripheral surface of the seal ring, and 4b is a formation surface of the inner peripheral surface of the seal ring. The gate 7 is inclined and connected to the inner peripheral surface 4b of the seal ring.
The movable side template 3 is provided with a protruding pin 8 for taking out a molded product. Further, the ejection pin 8 can eject the resin in the molding material passage portion constituted by the sprue 5, the runner 6 and the gate 7 in order to cut the resin in the gate 7 portion from the molded product in the cavity 4 simultaneously with the ejection of the molded product. The location is also provided.

  The runner 6 may have any shape that allows the molding material from the sprue 5 to flow into the cavity 4 through the gate 7 and can be projected from the template together with the gate 7 that is a submarine gate when the molded product is ejected. For example, as shown in FIG. 1, each of the fixed side mold plate 2 and the movable side mold plate 3 is formed by forming a part of a recess for a runner and abutting both mold plates, or one mold There is a type in which a recess for a runner is formed on a plate and the two plates are joined together.

The shape of the connecting portion between the cavity 4 and the gate 7 will be described with reference to FIG. 2A shows an enlarged view of a portion A in FIG. 1, and FIG. 2B shows a view in the direction of arrow B in FIG. 2A.
The columnar gate 7 is connected to the inner peripheral surface 4b of the seal ring in an inclined manner. Note that the position of the gate 7 when the molded product is not a seal ring can be any position on the outer peripheral surface or inner peripheral surface of the molded product in the cavity.
Here, the degree of biting of the cylindrical gate 7 into the cavity 4, that is, the position in the vertical direction in the figure, and the inclination angle α of the gate 7 with respect to the inner peripheral surface 4 b of the seal ring are determined by the connection between the cavity 4 and the gate 7. The width and width W ₁ (gate port lateral width) may be any position and angle smaller than the cylindrical diameter W ₂ of the gate 7.
The inclination angle α is preferably 5 to 20 °. By setting it in this range, when the molded product is ejected, the gate port functions as a sharp blade, and smooth gate cutting is performed without generating burrs in the gate trace.
As shown in FIG. 2B, the gate port 7a has a substantially triangular shape when viewed in plan. In the drawing, the width W ₃ of the left vertical side is a connecting width between the cylindrical bottom surface 7 c of the gate 7 and the lower end surface 4 b of the cavity 4, and therefore is equal to or smaller than the cylindrical diameter W ₂ of the gate 7.

The area S ₁ of the gate port 7a is compared with the area S ₂ of the gate cylinder cross section 7b. Consolidated width W ₁ between the cavity 4 and the gate 7 is smaller than the cylindrical diameter W ₂ of the gate 7, and, considering that the width W ₃ or less cylindrical diameter W ₂ of the gate 7, the relationship between both area It becomes as shown in the following formula (4). The area S ₁ of the gate port 7a was calculated on the assumption that the gate port is substantially triangular.

Since the gate 7 has a cylindrical shape, the runner can be smoothly extracted from the mold without damaging the runner when the gate is cut. Moreover, coupled with the gate inclination angle α5 to 20 °, the resin is not forcibly removed from the gate 7 portion when the molded product is ejected, and the resin can be prevented from being broken at the portion.
By making the shape of the gate 7 cylindrical, and making the connection width in the cross section of the connection between the gate 7 and the cavity 4 smaller than the cylindrical diameter of the gate 7, the area S ₁ of the gate port 7 a becomes the gate cylindrical cross section 7 b. is smaller than an area S _2. For this reason, at the time of extrusion of the molded product, the resin is easily cut at the gate port 7a which is the connecting surface, and coupled with the gate inclination angle α5 to 20 °, the product and the gate are smoothly divided at the gate port. In addition, problems such as cold slug mixing are less likely to occur. Moreover, there is little abrasion of the gate 7 part, and the lifetime reduction of a metal mold | die can be suppressed.

Next, a method for manufacturing a seal ring using the injection mold of the present invention will be described with reference to FIG. FIGS. 3A to 3D are diagrams showing a manufacturing process of a seal ring by injection molding.
(1) Mold closing step: The fixed side mold plate 2 and the movable side mold plate 3 are brought into contact with each other to form a seal ring-shaped cavity 4. Further, the passage 10 of the molten resin material is formed by the sprue 5, the runner 6 and the gate 7 (FIG. 3A).
(2) Resin filling step: The molten resin 9 for molding is injected and filled into the cavity 4 through the passage 10 from the gate port 7a (FIG. 3B).
(3) Mold opening process: After the resin 9 in the cavity 4 and the passage 10 is cured through the pressure holding process and the cooling process, the movable side mold plate 3 is moved backward in the left direction in the drawing to open the mold. (FIG. 3C).
(4) Molded product ejecting step: The ejecting pin 8 is moved in the right direction in the drawing to eject the molded product 11 having the resin 9 cured and ejected from the cavity 4 (FIG. 3 (d)). Here, the cured cured resin 12 in the passage 10 is also ejected by the ejection pin 8. The end portion 12a of the cured resin 12 is projected by a projecting pin, and the runner 6 and the gate 7 portion of the cured resin 12 are also projected. The cured resin 12 is cut from the molded product 11 at the gate opening 7 a, that is, the gate 7 connection surface of the cavity 4 at the time of the protrusion.
The template and the projecting pin are moved by driving means such as a hydraulic cylinder (not shown).

The resin material used in the present invention is a synthetic resin having a heat resistant temperature of 110 ° C. or higher. Such a synthetic resin is generally called an engineering plastic (engineering plastic). Engineering plastics have higher heat resistance and mechanical properties than general-purpose plastics, and they are often used for precision molded products with strict dimensional accuracy and functional parts that require high heat resistance.
Engineering plastics having a heat-resistant temperature of 110 to 150 ° C. are called general-purpose engineering plastics, and those having higher temperature are called super engineering plastics. Specific examples of super engineering plastics include aromatic resins such as polyphenylene sulfide (PPS) resin, polyetherimide resin, aromatic polyamideimide (PAI) resin, thermoplastic polyimide resin, and wholly aromatic polyester resin. Polyester resins, polyamide resins such as 46 nylon and 9T nylon, polycyanoaryl ether resins such as polyether nitrile resins, aromatic polyether ketone resins such as polyether ketone (PEK) resins and polyether ether ketone (PEEK) resins Etc.
Among engineering plastics, super engineering plastics are reinforced by blending glass fibers, carbon fibers, or mineral whiskers, and are often used for various functional parts, but such reinforcing materials are harder than resins and are used for gate cutting. This will cause damage to the mold and shorten the mold life. However, the submarine gate of the present mold has a connecting width in the cross section of the connecting portion between the submarine gate and the cavity that is smaller than the gate cylinder diameter and is inclined at an angle of 5 to 20 ° with respect to the submarine gate connecting surface of the cavity. Therefore, as shown in FIG. 4 (a), the fibrous reinforcing material 9a passing through the gate port 7a stands with respect to the gate port 7a, which is compared with the conventional one shown in FIG. 4 (b). Thus, the cut area of the fiber is small, so that it is possible to suppress a decrease in the life of the mold.

In addition, since the gate 7 is inclined at an angle of 5 to 20 ° with respect to the gate connection surface of the cavity, the resin removal of the gate 7 portion is not forced and the resin is not forcibly removed in the molded product ejection step. Breakage can be prevented.
In addition, engineering plastics having mechanical properties of a tensile strength of 50 Mpa or more and a tensile elongation of 20% or less, especially when formed using a conventional submarine gate, had noticeable burrs in the gate traces and mixed cold slugs. The use of the mold was eliminated.

  The resin seal ring manufactured by the above method is excellent in sealing performance, heat resistance, slidability, and the like because there is no burr in the gate trace and no cold slug is mixed. Excellent product quality uniformity.

  The injection mold of the present invention has a submarine gate shape that is not a tapered shape but a cylindrical shape, which is inclined and connected to the cavity, so that a sufficient resin material passage diameter and gate opening area are secured. it can. As a result, even when a super engineering plastic having a mechanical property of a tensile strength of 50 Mpa or more and a tensile elongation of 20% or less is used, the resin can be suitably used without clogging. Further, even when a resin containing a fibrous reinforcing material such as glass fiber is used, breakage of the resin at the gate portion and wear of the mold at the portion can be suppressed.

Example A 100-shot injection molding of a seal ring having an outer diameter of 32 mm, an inner diameter of 28 mm, and a width of 2 mm was performed using the mold of the present invention. A PEEK resin composition containing 15% by weight of carbon fibers and 10% by weight of PTFE resin was used as a molding material.
An appearance survey was conducted on 100 injection-molded seal rings, and the number of seal rings in which burrs, cold slugs, etc. were generated was examined. The results are shown in Table 1. The gate mark was substantially triangular as shown in FIG.

Comparative Example A seal ring having the same shape as the example (outer diameter 32 mm, inner diameter 28 mm, width 2 mm) was injection-molded 100 shots using a conventional die having a tapered submarine gate shown in FIG. The same PEEK resin composition as in the example was used as the molding material.
An appearance survey was conducted on 100 injection-molded seal rings, and the number of seal rings in which burrs, cold slugs, etc. were generated was examined. The results are shown in Table 1.

  In the comparative example, generation of burrs, cold slugs, etc. was observed in a total of 71 pieces, whereas generation of burrs, cold slugs, etc. was not observed in the seal ring manufactured using the injection mold of the present invention. Everything was good.

  The injection mold of the present invention is an injection mold having a submarine gate, and the molded product does not cause burrs at the gate marks or cold slugs, so that various precision molded products can be manufactured. Available to: Further, as a molding material, it can be suitably used for super engineering plastics in which burrs are generated in gate marks and cold slugs are extremely mixed.

It is a cavity periphery sectional view of the injection mold concerning one example of the present invention. It is the A section enlarged view in FIG. It is a figure which shows the manufacturing process of the seal ring of this invention. It is a figure which shows the orientation state of the fibrous reinforcement in the gate opening vicinity. It is gate periphery sectional drawing which shows the conventional submarine gate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection mold 2 Fixed side die plate 3 Movable side die plate 4 Cavity 5 Sprue 6 Runner 7 Submarine gate 8 Extrusion pin 9 Molten resin 10 Resin passage 11 Molded article 12 Cured resin

Claims (5)

An injection mold used when injection molding a synthetic resin having a heat resistant temperature of 110 ° C. or higher,
The injection mold includes a fixed side mold plate, a movable side mold plate that abuts on the fixed side mold plate to form a cavity, and a submarine gate connected to the cavity.
The submarine gate has a cylindrical shape, the connection width in the cross section of the connection portion between the submarine gate and the cavity is smaller than the gate cylinder diameter, and is inclined at an angle of 5 to 20 ° with respect to the submarine gate connection surface of the cavity. An injection mold characterized by being made.   2. The injection mold according to claim 1, wherein the synthetic resin is a synthetic resin composition containing 5% by volume or more of a harder filler than the base resin.   The injection mold according to claim 1 or 2, wherein the synthetic resin has a tensile strength of 50 Mpa or more and a tensile elongation of 20% or less. A mold closing step of forming a cavity by abutting the fixed side mold plate and the movable side mold plate, a resin filling step of injecting molten resin into the cavity from a submarine gate connected to the cavity, and after molding A method of manufacturing a seal ring comprising a molded product ejection step of projecting a molded product,
The submarine gate has a cylindrical shape, and the connection width in the cross section of the connection between the submarine gate and the cavity is smaller than the gate cylinder diameter,
The method of manufacturing a seal ring, wherein the resin in the submarine gate portion is cut from the molded product at the submarine gate connecting surface of the cavity in the molded product ejection step. A resin seal ring manufactured by injection molding,
The injection molding process includes a mold closing process in which a fixed mold plate and a movable mold plate are abutted to form a cavity, and a molten resin is injected and filled into the cavity from a submarine gate connected to the cavity. Comprising a resin filling step and a molded product ejection step for ejecting the molded product after molding,
The submarine gate has a cylindrical shape, and the connection width in the cross section of the connection between the submarine gate and the cavity is smaller than the gate cylinder diameter,
The resin seal ring, wherein the resin in the submarine gate portion is cut from the molded product at the submarine gate connecting surface of the cavity in the molded product ejection step.

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