JP7231218B2 - injection mold - Google Patents

Description

The present invention relates to injection molds.

2. Description of the Related Art Conventionally, there is known a technique of molding a resin container, such as a cup, having a bottom portion and a side wall portion using an injection mold (hereinafter also simply referred to as “mold”). Generally, the mold has a male mold with protrusions and a female mold with recesses corresponding to the protrusions of the male mold. Hereinafter, the male mold will be referred to as the "core" and the female mold as the "cavity".

A molded product is molded by injecting a molten resin into a cavity space (molding space) formed by a male mold (core) and a female mold (cavity). After molding, when the molded product shrinks due to the solidification of the resin in the cooling cycle, the inner peripheral surface of the molded product normally adheres to the outer peripheral surface of the protruding part of the core, while the outer peripheral surface of the molded product moves away from the concave part surface of the cavity. It tends to flake off. For this reason, conventionally, when the mold is opened and the solidified molded product is removed from the mold, there is a method of pushing the molded product with an ejector pin to remove it from the core. There is a problem that traces of the ejector pin remain on the molded product.

As an example of conventional technology for releasing a molded product without leaving traces of ejector pins, Patent Document 1 discloses a method using compressed air. In the case of the technique disclosed in Patent Document 1, a plurality of ventilation grooves are provided side by side with openings at intervals at the position of the root end of the side wall portion on the outer peripheral surface of the core protruding portion, and the compressed air flows from each of the ventilation grooves. It is blown towards the core end of the molded article. Then, the compressed air enters between the outer peripheral surface of the core protruding portion and the molded article, and the entering compressed air promotes release of the molded article from the mold.

Japanese Patent Publication No. 48-030134

However, in the case of Patent Literature 1, the method is such that the air is partially fed into the annular end portion of the side wall portion of the molded article in the circumferential direction rather than the entire circumference of the annular end portion. Therefore, if the molded product is not completely cooled and has residual heat, air pressure is partially applied to the molded product, which may warp or distort the molded product after releasing from the mold.

The present invention has been made by paying attention to the above-mentioned problems, and is an injection molding mold that can release a molded product smoothly and suppress warpage and distortion when releasing the molded product by blowing air. intended to provide

A mold for injection molding according to claim 1 has a cavity that forms an outer peripheral surface of a molded product, a core body that forms an inner peripheral surface of the molded product, and a core substrate that supports the core body, wherein the cavity and a core forming a cavity space into which resin is injected by mold clamping; It has a core base, a core annular hole formed in the outer peripheral surface of the core base body fitted with the core through hole, and a core air passage formed in the core base and sending air to the core annular hole. .

In the above configuration, a molded product is formed by injecting a resin into a cavity space formed by clamping the cavity and the core. When opening the cavity and the core, air is supplied through the core air passage to the core annular hole formed in the outer peripheral surface of the core substrate. The air supplied to the core annular hole spreads over the entire peripheral surface of the core annular hole, flows between the mating surfaces of the core through hole and the core substrate, and further flows between the outer peripheral surface of the core and the inner peripheral surface of the molded product. surface to between the top surface of the core and the bottom surface of the molded article, pushing the molded article out of the core. Therefore, the molded product can be removed from the core without using an ejector pin, so that the molded product does not leave traces of the pins. In addition, since the air flows around the entire circumference of the molded product, air pressure is evenly applied to the entire inner peripheral surface of the molded product compared to a method in which air is partially sent in the circumferential direction of the molded product. Even if the molded product has residual heat during molding, the molded product is less likely to warp or distort.

In the injection mold according to claim 2, a fitting surface between the core through-hole and the core substrate is inclined toward the central axis of the core.

In the above configuration, when the cavity and the core are opened, the cavity moves and the core base also moves, forming a gap between the mating surfaces of the core through-hole and the core substrate. The formed air gap allows air sent from the core annular hole to flow between the outer peripheral surface of the core and the inner peripheral surface of the molded product. In other words, simply by sliding the cavity and the core base, the air sent out from the core annular hole can be guided to the end of the molded product.

In the injection mold according to claim 3, the cavity is formed with a cavity through-hole that fits with the core and forms the cavity space between the outer peripheral surface of the core and the peripheral surface of the molded product. a main body, a cavity base fitting with the cavity through hole to form the cavity space between the top surface of the core and the bottom surface of the molded product, and a gate provided in the cavity base for injecting resin into the cavity space. , a cavity annular hole formed in the outer peripheral surface of the cavity base body to be fitted with the cavity through hole, and a cavity air passage provided in the cavity main body for sending air to the cavity annular hole.

In the above configuration, when opening the cavity and the core, air is supplied through the cavity air passage to the cavity annular hole formed in the outer peripheral surface of the cavity base. The air supplied to the cavity annular hole spreads over the entire peripheral surface of the cavity annular hole, and then flows between the outer peripheral surface of the cavity base body and the cavity through hole that are fitted to each other. The air then reaches between the inner peripheral surface of the cavity and the outer peripheral surface of the molded product and between the lower surface of the cavity base and the bottom surface of the molded product, and pushes the molded product out of the cavity. Therefore, it is possible to prevent the molded product from sticking to the cavity.

A mold for injection molding according to claim 4 comprises a cavity forming an outer peripheral surface of a molded product,
A core that forms the inner peripheral surface of the molded product and is clamped with the cavity to form a cavity space into which resin is injected; and a wedge-shaped core that opens at the end of the molded product on the outer peripheral surface of the core. A recess and a core air passageway formed in the core for channeling air to the core recess.

In the above configuration, the wedge-shaped core recess can increase the pressure of the air blown to the end of the molded product, so that the molded product can be released from the mold more smoothly.

According to the injection mold according to the present invention, when the molded product is released by blowing air, the molded product can be released smoothly, and warping and distortion can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing explaining the structure of the injection mold which concerns on 1st Embodiment of this invention. FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1; It is sectional drawing explaining the mold release method using the injection mold which concerns on 1st Embodiment (part 1). It is sectional drawing explaining the mold release method using the injection mold which concerns on 1st Embodiment (part 2). 5 is an enlarged view of a portion B in FIG. 4. FIG. FIG. 4 is a perspective view illustrating a state in which an annular gap is opened in the injection molding die according to the first embodiment; 6 is an enlarged view of part C in FIG. 5. FIG. It is sectional drawing explaining the mold release method using the injection mold which concerns on 1st Embodiment (part 3). FIG. 4 is a perspective view illustrating a state in which air flows over the outer surface of the core of the injection mold according to the first embodiment; FIG. 4 is a cross-sectional view explaining a mold release method using the injection mold according to the first embodiment (No. 4); FIG. 5 is a partial cross-sectional view illustrating the configuration of a core base of an injection mold according to a modification of the first embodiment; FIG. 4 is a cross-sectional view illustrating the configuration of an injection mold according to a second embodiment of the present invention; 13 is a cross-sectional view taken along line 13-13 in FIG. 12; FIG.

First and second embodiments will be described below. In the following description of the drawings, identical or similar parts are given the same or similar reference numerals. However, the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each device and each member, etc. are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following description. In addition, there are portions with different dimensional relationships and ratios between the drawings.

-First Embodiment-
<Structure of mold for injection molding>
As shown in FIG. 1, an injection mold (mold) 10 according to the first embodiment is a mold for molding a container such as a cup. and a base 16 . The cavity 12 forms the outer peripheral surface of the molded product, and the core 14 forms the inner peripheral surface of the molded product.

In the first embodiment, the core 14 is placed on the core receiving plate 32 , and the first seal member 34 is annularly provided between the core 14 and the core receiving plate 32 in plan view. The first seal member 34 is, for example, an elastic silicone rubber O-ring.

As shown in FIG. 2, the mold 10 has a substantially rectangular shape in plan view. Through holes 43 are concentrically provided in the core receiving plate 32 and the cavity 12 at four corners of the rectangle, and guide pins 44 are provided inside the through holes 43 correspondingly. FIG. 2 illustrates through holes 43 provided in the core receiving plate 32 . The guide pins 44 align the cavity 12 and the core base 16 on the movable side and the core 14 on the stationary side when opening and closing the mold.

The cavity 12 and the core base 16 are slidable in proximity to the core 14 . Specifically, the cavity 12 and the core base 16 are moved along the opening and closing direction of the mold (vertical direction in FIG. 1) by a driving device (not shown).

The mold 10 illustrated in FIG. 1 is in a clamped state, and the cavity 12 is in close contact with the core base 16 and the core base 16 is in close contact with the core 14 . As shown in FIG. 3, a molten resin is injected into a cavity space 50 surrounded by the cavity 12, the core 14 and the core base 16 during molding, and the injected molten resin is cooled in the cavity space 50 and solidified. After that, the molded product 52 is removed from the mold 10 .

As shown in FIG. 3, the molded article 52 is cylindrical and has a bottom portion 54 , side wall portions 56 and a collar portion 58 . Since the side wall portion 56 rises from the entire peripheral edge of the bottom portion 54, an annular opening is formed at the lower end of the side wall portion 56 in FIG. The flange portion 58 protrudes laterally outward from the lower end of the side wall portion 56 in FIG. It should be noted that the flange portion 58 is not essential in the present invention. In addition, the molded product 52 is bilaterally symmetrical with respect to the central axis A of the cylinder.

(cavity)
Next, the cavity 12, the core 14 and the core base 16 will be explained in detail. As shown in FIG. 1, cavity 12 comprises cavity body 22 and cavity substrate 24 . The cavity molds the outer peripheral surface of the molded product 52 .

The cavity body 22 is fitted with the core 14 to form a cavity space 50 between the outer peripheral surface of the core 14 and the peripheral surface of the molded product 52 . The cavity main body 22 has a hollow cylindrical shape, and a cavity through hole 22A is formed inside. In the upper and lower portions of the cavity body 22, recesses that are circular in plan view are provided, and an O-ring 23 is provided inside the recess. The upper O-ring 23 enhances the adhesion between the cavity main body 22 and the cavity receiving plate 70 , and the lower O-ring 23 enhances the adhesion between the cavity main body 22 and the core base 16 .

The cavity base body 24 has a cylindrical shape and is fitted inside the cavity body 22 at the upper bottom position in FIG. 1 so as to close the cavity through hole 22A. The cavity base 24 is fitted into the cavity through hole 22A to form a cavity space 50 between the top surface 14A of the core 14 (see FIG. 3) and the bottom surface 54A of the molded article 52. As shown in FIG. Although not shown, a slight gap is formed between the cylindrical outer peripheral surface of the cavity base 24 and the cavity through hole 22A. The width of the gap is set to a width that allows air to flow but prevents molten resin from entering, for example, about 0.03 mm.

A cavity annular hole 26 is dug in an annular shape in a plan view on the entire outer peripheral surface of the cavity base 24 . The cavity annular hole 26 is, for example, a hole formed by covering the opening of a groove dug in the outer peripheral surface of the cavity base 24 with the inner surface of the cavity main body 22, and is considered to be closed or substantially closed. can be made. As shown in FIG. 1, the cross-sectional shape of the cavity annular hole 26 is semicircular. Cavity annular hole 26 is a passageway for high pressure air.

A tubular cavity air passage 28 is provided inside the cavity main body 22 , and the cavity air passage 28 opens into the cavity annular hole 26 . The cavity air passage 28 is connected through a first ventilation pipe 62 to an air supply device 60 provided outside the mold 10 . Air from air supply 60 is directed to cavity annular bore 26 by cavity air passage 28 .

The cavity 12 is joined to the lower side of the cavity receiving plate 70 located on the upper side in FIG. A gate 74 for injecting resin into the cavity space 50 is provided in the cavity base body 24 so as to extend along the central axis A. As shown in FIG. Specifically, in FIG. 1, a sprue bushing 72 is provided through the cavity 12 at the center of the cavity receiving plate 70 in the left-right direction, and a gate 74 is formed inside the sprue bushing 72 . A lower end of the gate 74 in FIG. 1 opens into the cavity space 50 below the cavity base 24 .

A locate ring 76 is provided on the upper portion of the cavity receiving plate 70 in FIG. When the mold is opened, the cavity 12, the cavity receiving plate 70, the sprue bushing 72, and the locate ring 76 are integrally slid along the central axis A to the opposite side (the upper side in FIG. 1) of the core 14. move away from

(core)
Core 14 includes a core plate 36 and a core body 38 . The core plate 36 has a through hole inside and is arranged on the lower side facing the cavity 12 positioned on the upper side in FIG. The core 14 is clamped with the cavity 12 to form a cavity space 50 into which resin is injected. Also, the core 14 forms the inner peripheral surface of the molded product 52 .

The core plate 36 has a ring shape, and a columnar core body 38 is fitted in a central hole in the left-right direction in FIG. The core body 38 has a core body 38A, a core substrate 38B and a core bottom 38C. The core bottom portion 38</b>C has a cylindrical shape and is fitted into a through hole of the core plate 36 . The core body 38A and the core substrate 38B protrude from the core plate 36 toward the cavity 12 side (upper side in FIG. 1). The core body 38A corresponds to the position of the side wall portion 56 of the molded product 52, and the outer peripheral surface of the core body 38A forms the inner peripheral surface of the side wall portion 56 of the molded product 52. As shown in FIG.

The core substrate 38B is a region of the core 14 that supports the core body 38A forming the inner peripheral surface of the molded product 52 from below. The core substrate 38B has a smaller diameter toward the cavity 12 side and a trapezoidal cross-sectional shape. Therefore, the outer peripheral surface 38B1 of the core substrate 38B approaches the central axis A as it goes from the core 14 side (lower side in FIG. 1) toward the cavity 12 side (upper side in FIG. 1). Further, the outer peripheral surface 38B1 of the core base body 38B is fitted with the core through hole 16A. A core annular hole 80 is formed in an annular shape in plan view in the outer peripheral surface 38B1 of the core base body 38B. The core annular hole 80 is, for example, a hole formed by covering the inner surface of the core base 16 with the opening of a groove dug in the outer peripheral surface of the core substrate 38B, and is closed or substantially closed. can be regarded. The cross-sectional shape of the core annular hole 80 is semicircular. The core annular hole 80 is a passageway for high pressure air.

In the upper portion of the core plate 36, a recess 36A is provided annularly in plan view so as to surround the core substrate 38B, and a second seal member 42 is housed inside the recess 36A (see FIG. 2). The recess 36A for housing the second seal member 42 may be provided in the lower portion of the core base 16, or may be provided on both the core plate 36 and the core base 16 so as to overlap each other in plan view. may be provided.

The second sealing member 42 is, like the first sealing member 34, an elastic silicon rubber O-ring or the like. As shown in FIG. 1, the second seal member 42 is pushed downward and compressed by the core base 16 in the clamped state.

Although illustration is omitted, a plurality of holes extending in the vertical direction can be provided inside the core body 38 . Also, although not shown, a water discharge pipe is inserted into each hole, and the water discharge pipe is connected to a cooling water tank outside the mold 10 . The cooling water discharged inside the hole inside the core body 38 through the water discharge pipe contacts the inner wall surface of the hole, thereby cooling the core body 38 from the inside. The cooling water that has been used for cooling and has been heated is recovered and cooled outside, and then returned to the cooling water tank and used for cooling the mold 10 .

(core base)
As shown in FIGS. 1 and 2, the core base 16 is ring-shaped, and a core through hole 16A is formed inside the ring. The core base 16 is, for example, a stripper plate, and a core substrate 38B is fitted in the core through hole 16A. In the clamped state shown in FIG. 1, the upper surface of the core base 16 is in contact with the lower surface around the opening of the concave portion of the cavity 12 (face-bonded).

A depression 40A is provided in the upper portion of the core base 16 in FIG. 1 at the end on the core through hole 16A side. The position of the bottom surface of the recess 40A in FIG. 1 is lower than the position of the top surface of the recess 40A outside the recess 40A where the recess 40A is not provided. During molding, the collar portion 58 of the molded product 52 is molded on the bottom surface of the recess 40A. The depth of the depression 40A (the length measured along the vertical direction in FIG. 1) is substantially equal to the thickness of the collar portion 58. As shown in FIG.

As shown in FIG. 1, when the core body 38 is fitted into the core through hole 16A of the core base 16 during die clamping, the outer peripheral surface 38B1 of the core substrate 38B and the core through hole 16A (end surface) of the core base 16 are aligned. are joined facing each other. Like the outer peripheral surface 38B1 of the core substrate 38B, the core through-hole 16A approaches the central axis A from the core 14 side (lower side in FIG. 1) toward the cavity 12 side (upper side in FIG. 1). That is, the mating surface between the core through-hole 16A and the core base body 38B is inclined toward the central axis A of the core 14 .

A core air passage 82 is formed inside the core base 16, and one end of the core air passage 82 opens into the core through hole 16A. A second ventilation pipe 84 is inserted into the other end of the core air passage 82 , and the second ventilation pipe 84 is connected to the air supply device 60 . A core air passage 82 channels air to the core annular bore 80 .

(Air supply device)
The air supply device 60 includes a compressor 64 and a switching section 66 connected to the compressor 64 . The compressor 64 compresses the air and sends it out to the switching section 66 . In the present invention, other than air, other gases such as nitrogen can be used as appropriate. The switching unit 66 is connected to the first ventilation pipe 62 and the second ventilation pipe 84 of the mold 10 via opening/closing valves 68 respectively. The destination of the air is selected by the switching unit 66 and the open/close valve 68 .

<How to release the molded product>
Next, a method of releasing the molded product 52 from the mold 10 according to the first embodiment will be described with reference to FIGS. 3 to 10. FIG. First, as shown in FIG. 3, molten resin is injected from the gate 74 into the cavity space 50 of the clamped mold 10 . Air in the cavity space 50 is discharged from a gas escape path (not shown), and the cavity space 50 is filled with molten resin. For example, the gas may be discharged by opening the on-off valve 68 (see FIG. 1) connected to the core air passage 82 via the second ventilation pipe 84 . Then, the molded product 52 is molded by cooling and solidifying the molten resin.

Next, an air supply device 60 (see FIG. 1) is used to send air G through the cavity air passage 28 into the cavity annular hole 26 of the cavity 12 . As shown in FIG. 3, the air G that has been sent inside the cavity annular hole 26 travels along the outer peripheral surface of the cavity base 24 in the entire circumferential direction, and flows between the cavity base 24 and the cavity main body 22. flows into the molded product 52 side from a slight gap in the .

The air G that has flowed in enters the interface between the lower surface of the cavity base 24 and the upper surface of the bottom of the molded product 52 and the interface between the cavity through hole 22A and the outer peripheral surface of the side wall portion 56 of the molded product 52 . The entry of the air G promotes release of the molded product 52 from the cavity 12 . The supply of the air G may be stopped as appropriate according to the release state of the molded product 52 from the cavity 12 .

Next, as shown in FIG. 4, the cavity 12 is slid upward by the driving device to separate the cavity 12 from the core 14 and the mold 10 is opened. Next, the core base 16 is slid toward the cavity 12 side (upper side in FIG. 4) toward the upper empty space. Note that the cavity 12 and the core base 16 may be slid at the same time.

FIG. 5 illustrates a case where the core base 16 is separated from the core 14 by a certain distance D and moved (raised). As the core base 16 moves, a force is applied to the lower part of the molded product 52 so that the molded product 52 is lifted upward. When the molded product 52 and the core body 38 are firmly in contact with each other when a load is applied, a force is applied to the molded product 52 so as to compress the molded product 52 from below. Stress concentrates.

For this reason, the fixed distance D is set so that when the core base 16 slides, the molded product 52 is not plastically deformed by the stress concentrated on the end of the molded product 52, and is kept within a range in which elastic deformation is possible. ing. For example, when the resin of the molded product 52 is polypropylene (PP), the wall thickness of the side wall portion 56 is substantially uniform, and the wall thickness is as thin as about 0.2 mm to 0.5 mm, the constant distance D can adopt a value of about 0.1 mm to 0.2 mm.

Further, as shown in FIG. 5, the sliding of the core base 16 reduces the force with which the core base 16 compresses the second seal member 42, so that the second seal member 42 expands upward. Due to the expansion, the upper end of the second seal member 42 shown in FIG. Therefore, the gap 86 does not communicate with the outside of the mold 10, and the airtightness of the gap 86 is enhanced.

As shown in FIG. 6, by sliding the core base 16, a gap 86 is formed between the core through-hole 16A of the core base 16 and the outer peripheral surface 38B1 of the core substrate 38B. The gap 86 functions as a blast path for the air G, and one end of the gap 86 is positioned at the annular end of the side wall portion 56 of the molded product 52 on the outer peripheral surface 38B1 of the core substrate 38B, depending on the shape of the end. It opens circularly.

For this reason, as shown in FIG. 5, the boundary between the inner peripheral surface of the side wall portion 56 of the molded product 52 and the outer peripheral surface of the core body 38A is exposed at the position of the upper opening of the gap 86 . 5 and the bottom surface of the recess 40A of the core base 16 are exposed at the position of the opening of the gap 86. As shown in FIG.

As shown in FIG. 7, the opening width W of the gap 86 is measured between the outer peripheral surface of the core body 38A and the upper end of the core base 16. As shown in FIG. The opening width W depends on the fixed distance D and the inclination angle with respect to the central axis A, but can be set within a range of about 0.01 mm to 0.09 mm, for example.

Next, as shown in FIG. 8, the air supply device 60 is used to send the air G into the gap 86 via the core air passage 82 . The air G that has been sent flows toward the upper side of the gap 86 in FIG. 8 and also flows into the core annular hole 80 . It should be noted that the flow of the air G toward the lower side of the gap 86 is blocked by the second seal member 42 .

As shown in FIG. 9, inside the core annular hole 80, the air G that has flowed into the core annular hole 80 flows along the outer peripheral surface 38B1 of the core base body 38B in the entire circumferential direction, and flows through the gap 86 into the molded product. It flows into the 52nd side. In FIG. 8, the air G that has flowed in passes through the interface between the outer peripheral surface of the core body 38 and the inner peripheral surface of the side wall portion 56 of the molded product 52, the bottom surface of the recess 40A of the core base 16, and the flange of the molded product 52. It enters the interface with the lower surface of the portion 58 . The entering air G promotes release of the molded product 52 from the core 14 and the core base 16 . Then, as shown in FIG. 10, the molded product 52 can be removed from the core 14 after the cavity 12 and the core base 16 are further moved.

(Effect)
In the mold 10 according to the first embodiment, a molded product 52 is formed by injecting a resin into a cavity space 50 formed by clamping the cavity 12 and the core 14 together. When opening the cavity 12 and the core 14, air G is supplied through the core air passage 82 to the core annular hole 80 formed in the outer peripheral surface 38B1 of the core substrate 38B.

The air G supplied to the core annular hole 80 spreads over the entire peripheral surface of the core annular hole 80, and then flows between the core through hole 16A and the core substrate 38B. In addition, the air G further flows between the outer peripheral surface of the core 14 and the inner peripheral surface of the molded product 52, reaches between the top surface 14A of the core 14 and the bottom surface 54A of the molded product 52, and is molded from the core 14. Product 52 is extruded.

Therefore, the molded product 52 can be removed from the core 14 without using an ejector pin, so that the molded product 52 does not leave traces of the pins. In addition, since the air G wraps around the entire circumference of the molded product 52, the air pressure is evenly applied to the entire inner peripheral surface of the molded product 52, compared to a method in which the air G is partially sent in the circumferential direction of the molded product 52. Added. Therefore, even if the molded product is not completely cooled and has residual heat, it is difficult for the molded product 52 to warp or distort due to the applied air pressure. Therefore, according to the first embodiment, when air is blown to release the molded product 52, the molded product 52 can be smoothly released from the mold, and warpage and distortion can be suppressed.

Further, in the first embodiment, the mating surface between the core through-hole 16A and the core base body 38B is inclined toward the central axis A of the core 14 . Therefore, when the cavity 12 and the core 14 are opened, the cavity 12 moves upward and the core base 16 also moves, creating a gap between the mating surfaces of the core through-hole 16A and the core substrate 38B. It is formed. The formed gap allows the air G sent out from the core annular hole 80 to flow between the outer peripheral surface of the core 14 and the inner peripheral surface of the molded product 52 . That is, the air G sent out from the core annular hole 80 can be guided to the end of the molded product 52 simply by sliding the cavity 12 and the core base 16 .

In addition, in the first embodiment, the second sealing member 42 further enhances the airtightness of the gap 86, so that the air G can be blown to the ends more forcefully. Therefore, the molded product 52 can be released from the mold more smoothly.

Further, according to the first embodiment, when the cavity 12 and the core 14 are opened, air is supplied to the cavity annular hole 26 formed in the outer peripheral surface of the cavity base 24 through the cavity air passage 28 . The air supplied to the cavity annular hole 26 spreads over the entire peripheral surface of the cavity annular hole 26, and then flows between the outer peripheral surface of the cavity base 24 and the cavity through hole 22A which are fitted to each other. The air then reaches between the inner peripheral surface of the cavity 12 and the outer peripheral surface of the molded product 52 and between the lower surface of the cavity base 24 and the bottom surface 54A of the molded product 52 to push the molded product 52 out of the cavity 12 . Therefore, sticking of the molded product 52 to the cavity 12 can be suppressed.

<Modification>
In the mold 10 illustrated in FIGS. 1 to 10, the core annular hole 80 communicating with the annular gap 86 was provided in the outer peripheral surface 38B1 of the core substrate 38B of the core body 38 of the core 14, but the present invention However, it is not limited to this. As in the case of the injection molding die (mold) 10A according to the modified example illustrated in FIG. . Other members of the mold 10A according to the modified example are equivalent to the members of the same name in the mold 10 shown in FIGS.

In the mold 10A according to the modified example as well, the air spreads over the entire peripheral surface of the core annular hole 80A and then flows between the core through hole 16A and the core substrate 38B. Further, the air flows between the outer peripheral surface of the core 14 and the inner peripheral surface of the molded product 52, reaches between the top surface of the core 14 and the bottom surface 54A of the molded product 52, and moves the molded product 52 from the core 14. Push out. Therefore, when air is blown to release the molded product 52, the molded product 52 can be smoothly released from the mold, and warpage and distortion can be suppressed. Other effects of the mold 10A according to the modified example are the same as those of the mold 10 shown in FIGS.

-Second embodiment-
In the mold 10 shown in FIGS. 1-8, the annular gap 86 was formed between the core 14 and the core base 16 by sliding the core base 16 away from the core 14. . However, in the present invention, the annular gap can be realized without the core base 16 being provided. For example, like an injection molding die (mold) 10B according to the second embodiment shown in FIG. 12, an annular gap 86A may always be open on the outer surface of the core 15.

A mold 10B according to the second embodiment has a cavity 12, a core 15, a core recess 87, and a core air passage 82A. Cavity 12 forms the outer peripheral surface of cylindrical molded article 52 . The core 15 is clamped with the cavity 12 to form a cavity space 50 (see FIG. 1) into which resin is injected, and also forms the inner peripheral surface of the molded product 52 . The molded product 52 of the second embodiment has a bottom portion 54 and a side wall portion 56, but does not have a flange portion 58 (see FIG. 3).

The core body 38 of the second embodiment has a core body 38A and a core bottom portion 38C, but the core substrate 38B (see FIG. 1) is not provided. As shown in FIG. 12, a gap 86A is provided between the outer peripheral surface of the core bottom portion 38C and the core through hole 16A of the core plate 36. As shown in FIG. One end of the gap 86A is opened in an annular shape at a position corresponding to the annular end of the side wall portion 56 of the molded product 52 on the outer peripheral surface of the core 15, as in the case of the first embodiment. . The thickness of the side wall portion 56 is, for example, about 0.2 mm, and the opening width of the gap 86A is, for example, about 0.03 mm.

As shown in FIG. 13, a plurality of core recesses 87 are provided at approximately equal intervals in the circumferential direction on the outer peripheral surface of the core bottom portion 38C at the height of the gap 86A. The core recess 87 opens at the end of the molded product 52 on the outer peripheral surface of the core 15 . The cross-sectional shape of the core recess 87 is wedge-shaped. In the core recessed portion 87 of the gap 86A, the gap between the outer peripheral surface of the core bottom portion 38C and the core through hole 16A of the core plate 36 gradually widens from the bottom to the top in FIG. 12 to a certain width. Afterwards, it gradually narrows.

A core air passage 82A is formed inside the core bottom portion 38C, and the core air passage 82A is connected to an air supply device (not shown). Also, the core air passage 82A communicates with the core recess 87 and sends air to the core recess 87.

12, two communicating grooves are provided as a gas guide path 92 and a gas escape path 94, respectively, on the upper surface of the core plate 36 on the cavity 12 side. The gas guide path 92 and the gas escape path 94 are used to discharge reaction gas generated by contact between the air in the cavity space and the molten resin when the molten resin is injected into the cavity space.

The gas guide path 92 on the right side in FIG. 12 opens into the cavity space. Also, the gas guide path 92 does not communicate with the gap 86A. The depth of the groove of the gas guide path 92 is, for example, about 0.03 mm, and the length of the groove (the length along the extending direction of the groove in FIG. 13) is, for example, about 3 mm.

On the other hand, the end of the gas escape path 94 on the left side in FIG. 12 opposite to the gas guide path 92 communicates with the outside. deeper than taxiway 92; Other members of the mold 10B according to the second embodiment are equivalent to the members of the same names in the molds 10 and 10A shown in FIGS.

(Effect)
According to the mold 10B according to the second embodiment, the gap 86A opens annularly on the outer peripheral surface of the core 15, as in the case of the first embodiment. Therefore, the air G flows between the outer peripheral surface of the core 15 and the inner peripheral surface of the molded product 52, reaches between the top surface 15A of the core 15 and the bottom surface 54A of the molded product 52, and flows from the core 15 to the molded product. Extrude 52. Therefore, as in the case of the first embodiment, when air is blown to release the molded product 52 from the mold, the molded product 52 can be released smoothly, and warping and distortion can be suppressed.

Further, in the second embodiment, the wedge-shaped core recess 87 provided in the gap 86A can increase the pressure of the air blown to the end of the molded product 52, so that the molded product 52 can be released more smoothly. Other effects of the mold 10B according to the second embodiment are the same as those of the molds 10 and 10A shown in FIGS.

<Other embodiments>
While the present invention has been described by the above disclosed embodiments, the statements and drawings forming part of this disclosure should not be construed as limiting the invention. It should be considered that various alternative embodiments, examples and operational techniques will become apparent to those skilled in the art from this disclosure.

For example, in the first embodiment, the cavity 12 is on the movable side and the core 14 is on the stationary side, and the cavity 12 is separated from the core 14 when the mold is opened. However, the present invention is not limited to this, and conversely, the cavity 12 may be on the fixed side, the core 14 may be on the movable side, and the male die may be separated from the female die. Further, the direction in which the cavity 12 and the core 14 are opened is not limited to the vertical direction, and may be horizontal.

In addition, in the first and second embodiments, the mold for molding one molded article 52 was exemplified, but the mold according to the present invention is not limited to this, and two or more molded articles 52 are molded. may be molded. Further, in this specification, the male mold is referred to as "core" and the female mold is referred to as "cavity". is not limited to The name of each device constituting the mold according to the present invention can be appropriately changed according to the overall shape of the molded product 52 to be molded.

1 illustrates the case where the core air passage 82 is provided inside the core base 16, the present invention is not limited to this. As shown in FIG. 12 , the core air passage 82A may be provided on the core 15 side and communicate with the gap 86 . Furthermore, in the mold 10 shown in FIG. 1, the core air passages, except for the core air passage 82, may be provided on the core 14 side and communicate directly with the core annular hole 80.

Further, the shape of the molded product 52 is not limited to a cylindrical shape, and may be, for example, a bowl shape, a dish shape, or a bottomless ring shape. Further, for example, a shape in which a plurality of rings are arranged and connected in a plane, a shape in which holes of various shapes are opened in a flat plate, or the like may be used. That is, the molded product has a single or a plurality of core portions (convex portions) provided in one mold component, and a single or a plurality of cavity portions (concave portions) corresponding to the core portions in the other mold component. ) can be used as long as it can be molded in a mold provided with. A coherent part of the molded product is generated in the single or plural core parts. ADVANTAGE OF THE INVENTION According to this invention, the mold release of the molded product from a contact|adherence part can be performed efficiently.

In addition, it is also possible to partially combine the configurations of the molds shown in FIGS. 1 to 13 to realize the injection mold according to the present invention. As described above, the present invention includes various embodiments and the like not described above, and the technical scope of the present invention is defined only by the matters specifying the invention in the scope of claims that are valid from the above description. is.

10, 10A, 10B injection mold 12 cavity 14, 15 cores 14A, 15A top surface 16 core base 16A core through hole 22 cavity main body 22A cavity through hole 24 cavity base 26 cavity annular hole 28 cavity air passage 38B core base 38B1 outer peripheral surface 50 cavity space 52 molded product 54A bottom surface 74 gates 80, 80A core annular holes 82, 82A core air passage 87 core recess A central axis G air

Claims (4)

a cavity forming the outer peripheral surface of the molded article;
a core that forms an inner peripheral surface of the molded product and is clamped with the cavity to form a cavity space into which resin is injected;
a core base whose upper surface is in contact with the lower surface around the opening of the recess in the cavity;
a core through hole formed in the core base and through which the core is opened and clamped;
a groove-shaped core annular recess formed along the entire circumference of the outer peripheral surface of the core;
Provided on the core or the core base, air is sent to the core annular recess when the mold is opened, and the molded product passes through a gap formed between the outer peripheral surface of the core and the inner peripheral surface of the core through hole. a core air passage for sending air toward the boundary between the inner peripheral surface of the end of the side wall and the outer peripheral surface of the core;
Injection mold with 2. The mold for injection molding according to claim 1, wherein the outer peripheral surface of said core and the inner peripheral surface of said core through-hole are inclined so as to approach the central axis side of said core from the bottom to the top. . The cavity is
a cavity body forming an outer surface of the molded article;
a cavity base forming the outer bottom surface of the molded product;
a groove-shaped cavity annular recess formed along the entire periphery of the outer peripheral surface of the cavity base;
Air is sent to the cavity annular concave portion provided in the cavity body, and is sent to the inner peripheral surface of the cavity body through a gap formed between the inner peripheral surface of the cavity body and the outer peripheral surface of the cavity base. a cavity air passage;
The mold for injection molding according to claim 1 or 2. core recesses formed in the bottom of the annular core recess at predetermined intervals in the circumferential direction and communicating with the core air passage and opening at the end of the side wall of the molded product;
The mold for injection molding according to claim 1 or 2.

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