JP7699492B2 - Ejector pin, molding device, and molding method - Google Patents

Description

This application relates to an ejector pin, a molding device, and a molding method.

In resin molding, if the gas (atmosphere) already in the mold when the resin is filled, or the gas that has evaporated from the resin, is not sufficiently discharged, molding defects such as gas burns occur. In addition, if the gas that has evaporated from the resin cools during processing, it can accumulate in the gas exhaust path and block the gas exhaust path. For this reason, regular maintenance of the gas exhaust path is necessary, but the mold must be disassembled and cleaned, and each time this is done, production must be stopped, the mold removed, and it must be disassembled and cleaned, which is a cumbersome process.

When discharging gas, a porous material is provided in the path to prevent the resin from being discharged together with the gas (see, for example, Patent Document 1 and Non-Patent Document 1).

Japanese Patent No. 664721 (paragraphs 0031, 0037 to 0049, Figures 1 to 4)

Misumi-VONA Online Catalog, Plastic Mold Parts > Date Mark / Gas Venting Related > Gas Venting Unit > GASEXIT PIN: Micro-penetrating porous material ejector pin, [Retrieved July 20, 2021], Internet <URL: https://jp.misumi-ec.com/vona2/detail/251303765293/>

However, the porous material that prevents the resin from leaking out is prone to clogging, and is therefore a component that requires periodic replacement or maintenance such as cleaning. As a result, every time clogging occurs, production must be stopped, the mold must be removed from the injection molding machine, and then the mold must be disassembled to remove the parts that are integrated with the porous material. In this case, production must be stopped for one to two days, shortening the maintenance period and making it difficult to improve productivity.

This application discloses technology to solve the problems described above, and aims to perform resin molding that is easy to maintain and highly productive.

The ejector pin disclosed in the present application is provided with: a main body portion having a columnar portion to be inserted into an ejector pin hole of a mold and a flange portion formed on a base side of the columnar portion; a disk portion connected to a tip portion of the columnar portion and forming a protruding surface; and a fastening portion extending from a surface of the disk portion opposite the protruding surface and constituting a detachable fastening mechanism between the tip portion and the main body portion, the radial inner portion being formed of a porous material that allows gas to pass therethrough in the axial direction, the main body portion being formed with a flow hole having one end that opens in a radial center portion of the tip portion and the other end that opens in a portion on the base side that is exposed from the mold , and the radial outer side of the porous material of the protruding surface portion is covered with a dense material that is formed to be denser than the porous material .

The ejector pin, molding device, and molding method disclosed in this application provide a removable, gas-permeable protruding surface on the ejector pin, making it possible to perform resin molding with easy maintenance and high productivity.

1A to 1C are a perspective view, a cross-sectional view, and an exploded view, respectively, of an ejector pin according to a first embodiment. FIG. 2 is a plan view of a molding die in which the ejector pin according to the first embodiment is mounted. 1 is a schematic diagram showing a state inside a molding device, including a cross-sectional view of a molding die equipped with an ejector pin according to a first embodiment. FIG. 4A and 4B are a plan view and a cross-sectional view, respectively, of a protruding surface portion of an ejector pin according to the first embodiment. 5A to 5C are schematic diagrams showing the states of each step in the first half of a resin molding process carried out by a molding device equipped with a molding die having an ejector pin mounted thereon according to the first embodiment. 6A and 6B are schematic diagrams showing the states of each step in the latter half of a resin molding process carried out by a molding device equipped with a molding die having an ejector pin mounted thereon according to the first embodiment. 5 is a flowchart for explaining operations in a resin molding process executed by a molding device equipped with a molding die having an ejector pin mounted thereon according to the first embodiment. FIG. 11 is a schematic diagram showing the state inside a molding device, including a cross-sectional view of a molding die equipped with an ejector pin according to a second embodiment. 9A to 9C are schematic diagrams showing the states of each step in the first half of a maintenance process after resin molding carried out by a molding device equipped with a molding die having an ejector pin according to the second embodiment. 10A and 10C are schematic diagrams showing the state of each step in the latter half of a maintenance process after resin molding carried out by a molding device equipped with a molding die having an ejector pin according to embodiment 2. 13 is a flowchart for explaining operations in a maintenance process after resin molding that is executed by a molding device equipped with a molding die having an ejector pin mounted thereon according to the second embodiment.

Embodiment 1.
1 to 7 are diagrams for explaining the configuration of an ejector pin according to the first embodiment, the configuration and operation of a molding apparatus using a molding die equipped with an ejector pin, and a molding method, and Fig. 1 is a perspective view of an ejector pin as viewed from the ejection surface side (Fig. 1A), a cross-sectional view along the axis taken along line A-A in Fig. 1A (Fig. 1B), and an exploded view of the ejector pin corresponding to Fig. 1A (Fig. 1C). Fig. 2 is a plan view of a movable die equipped with an ejector pin as viewed from the cavity surface side, and Fig. 3 is a schematic diagram showing the state in a molding apparatus having a gas control mechanism, including a cross-sectional view of a molding die equipped with an ejector pin corresponding to line B-B in Fig. 2.

Figure 4A is a plan view of the protruding surface of the ejector pin as viewed from the protruding surface side, and Figure 4B is a cross-sectional view taken along line C-C in Figure 4A. Figures 5A to 5C, as well as Figures 6A and 6B are schematic diagrams corresponding to Figure 3, showing the state of each step in a resin molding process carried out by a molding device equipped with a molding die equipped with an ejector pin, and Figure 7 is a flowchart for explaining the operations in the resin molding process, which proceed in the order of Figures 5A to 5C, 6A, and 6B.

The following describes the configuration of the ejector pin according to the first embodiment of the present application, as well as the configuration and operation of a molding device using a molding die equipped with the ejector pin, and a molding method. Note that the same components are given the same reference numbers, and their descriptions will not be repeated.

Before describing the ejector pin of the present application in detail, the basic configuration of the molding die will be described. As shown in FIG. 3, the molding die 4 forms a space 4g by butting a fixed die 3 fixed to a fixed end 61 of the molding device 100 against a movable die 2 supported by a drive end 62 having a drive mechanism and moving (left and right in the figure) when the die is opened and closed. Then, for example, a resin product can be molded according to the shape of the space by injecting a resin material from a spool 4s provided on the fixed die 3 toward the space 4g.

As shown in FIG. 2, the movable mold 2 is provided with ejector pins 10, the number of which is equal to the number of ejector pin holes 2he that penetrate in the depth direction and are distributed within the cavity surface 2fc that faces the space 4g. The ejector pins 10 have a flange portion 13 that is larger in diameter than the rod-shaped portion (columnar portion 12) that can slide within the ejector pin hole 2he. The left and right positions of the ejector pins 10 (ejection surface 10fp) are determined by sandwiching the flange portion 13 between ejector plates 5 that are composed of a front plate 51 close to the movable mold 2 and a rear plate 52 far from the movable mold 2.

When the ejector plate 5 is driven closer to the movable mold 2, the protruding surface 10fp of the ejector pin 10 moves in a direction protruding from the cavity surface 2fc, and when driven away, the protruding surface 10fp can be moved in a direction retracting. As described below, by protruding the ejector pin 10 from the cavity surface 2fc after mold opening, the molded resin product can be lifted from the cavity surface 2fc and easily removed from the molding mold 4. The movable mold 2 is provided with gas vents 2g at multiple locations on the outer edge of the cavity surface 2fc, which communicate from the space 4g to the outside.

The configuration up to this point is similar to that of a typical injection molding die, and based on this premise, we will explain the ejector pin 10, molding device 100, and characteristic parts of the molding method of the present application. Note that to simplify the explanation, the explanation will be based on a two-plate mold base, but the same applies to a three-plate mold base.

As shown in FIG. 1A, the ejector pin 10 of the present application is similar to a general ejector pin, in that a flange portion 13 having a larger diameter than the columnar portion 12 is provided at the base of the rod-shaped columnar portion 12 that slides inside the ejector pin hole 2he in order to be sandwiched by the ejector plate 5. As a characteristic configuration, as shown in FIG. 1B, a flow hole 10h is formed that passes through the center of the axis, and the protruding surface portion 11 that forms the protruding surface 10fp is configured to be gas permeable and communicate with the flow hole 10h.

As a result, the ejector pin 10 allows gas to flow between the flange 13 and the protruding surface 10fp through the flow hole 10h. The flange 13 with the flow hole 10h and the columnar portion 12 are integrated to form the main body 14, and as shown in FIG. 1C, the protruding surface portion 11 is formed with a male thread 11sm that corresponds to the female thread 12sf of the columnar portion 12, making it detachable from the columnar portion 12.

As shown in FIG. 4B, the protruding surface portion 11 is composed of a disk portion 111 that matches the outer diameter of the columnar portion 12 and forms the protruding surface 10fp, and a fastening portion 112 that protrudes concentrically from the surface opposite the protruding surface 10fp of the disk portion 111 and has a male thread 11sm. Furthermore, in terms of material, the portion arranged on the axial center side is a porous portion 11p in which fine communicating holes that allow gas to pass in the axial direction are formed by loosely bonding metal powder, for example, and which communicates with the flow hole 10h. On the other hand, the portion arranged on the outer periphery side is a dense portion 11r that is denser and more rigid than the porous portion 11p. Such a configuration can be easily manufactured using, for example, a 3D metal printer.

As shown in FIG. 4A, in the disk portion 111, the diameter Dp of the porous portion 11p is 2 to 4 mm smaller than the diameter Db (FIG. 1B) of the columnar portion 12. When the porous portion 11p is formed with a mesh structure, the mesh spacing is in the range of 20 to 70 μm. The thickness tm of the disk portion 111 is 1.5 to 3.0 mm. The dense portion 11r is configured to cover the outer periphery of the porous portion 11p, and the outer diameter Dr of the disk portion 111 is 2 to 4 mm larger than the diameter Dp of the porous portion 11p.

The male thread 11sm of the fastening portion 112 is a metric thread that is 1/2 the diameter Db of the columnar portion 12. For example, in the case of φ10 (Db = 10 mm), an M5 screw is used for fastening. The thread engagement length conforms to JIS B209-2. The axial center side of the male thread 11sm is connected to the porous portion 11p of the disk portion 111, and the portion of the fastening portion 112 where the male thread 11sm is formed is formed as densely as the dense portion 11r of the disk portion 111.

The steel material used for the columnar portion 12 and the flange portion 13 can be, for example, die steel such as SKD61, high-speed steel such as SKH51, or mold steel such as SUS440. The hole diameter Dh of the through hole 10h is set to 1/4 of the diameter Db of the columnar portion 12. For example, if the columnar portion 12 is φ10, the hole diameter Dh of the through hole 10h is φ2.5. In the portion where the protruding surface portion 11 of the columnar portion 12 is mounted, a screw mechanism that matches the screw size of the protruding surface portion 11 is provided with a fitting length conforming to JIS B209-2.

The columnar portion 12 and the flange portion 13 can be manufactured with the through holes 10h using a 3D metal printer. Alternatively, the outer shape can be machined by cutting, and then the through holes 10h can be machined by electric discharge machining or drilling with a drill press, and the female thread 12sf can be machined by tapping. The flange portion 13 has an outer diameter 1.5 to 5.0 times that of the columnar portion 12. The thickness t13 of the flange portion 13 is 4 mm or more and 6 mm or less. In either case, the flange portion 13 and the columnar portion 12 are part of the integrated main body portion 14, and are not joined by welding or fastened with screws, so as not to be affected by the attachment and detachment operation of the protruding surface portion 11.

The molding device 100, which is an injection molding machine corresponding to this, has, in addition to the mechanisms required for a general injection molding device, a gas control mechanism 7 that controls the flow of gas through the ejector pin 10 of the present application, as shown in FIG. 3. Furthermore, piping is provided for the flow holes 10h of each of the multiple ejector pins 10 from the flange portion 13 side to allow gas to be introduced and released.

The ejector pin 10 is mounted in the molding die 4 with the protruding surface portion 11 forming the protruding surface 10fp positioned on the side that contacts the resin molded product 900 (FIG. 5B) molded in the space 4g. At this time, the ejector pin 10 is fixed in place with the flange portion 13 sandwiched between the front plate 51 on the side closer to the space 4g and the rear plate 52 on the side farther from the space 4g. The front plate 51 is provided with a through hole (not shown) that allows the columnar portion 12 to pass through but not the flange portion 13, as in a typical injection molding device. The clearance between the columnar portion 12 and the through hole is in the range of +0.2 to +1.0 mm.

On the other hand, the rear plate 52 is provided with a hole of the same diameter as the flow hole 10h of the main body 14 as a vent hole (not shown) for allowing the gas discharged from the ejector pin 10 to flow in. A structure is provided on the rear surface of the rear plate 52 opposite the installation surface with the flange portion 13 to which an air coupler 75 to which an air tube 74 can be connected, to be attached. An air tube of φ6 to φ10 can be connected to the air coupler 75.

The molding die 4 is then divided into an upper surface portion and a lower surface portion, for example, starting from the center of the space 4g in the vertical direction (the up and down direction in FIG. 3). The air tube 74 connected to the ejector pin 10 on the upper surface portion is unified into one flow path using an L-shaped or T-shaped connection coupler, and then branched into two flow paths by a three-way valve 72. The air tube 74 can be switched by the valve 72 to connect to either the high-pressure flow path 73 side connected to a compressor 71 that compresses air, or the atmosphere side.

The air tube 74 connected to the ejector pin 10 on the bottom is also unified into one flow path using an L-shaped or T-shaped connection coupler, just like the top, and then branches into two flow paths by a three-way valve 72. The air tube 74 can be switched by the valve 72 to connect to either the high-pressure flow path 73 connected to the compressor 71 or the atmosphere.

The switching of the valve 72 is controlled by an output signal output from a control unit (not shown) of the molding device 100 in accordance with the progress of the molding process. Based on this configuration, the operation of the molding process by the molding device 100 using the ejector pin 10, that is, the molding method, will be explained with reference to the flowchart in Figure 7.

In the resin 900C filling process (step S100), as shown in FIG. 5A, the position (left-right direction in the figure) is adjusted so that the surface (protruding surface 10fp) of the protruding surface portion 11 of the ejector pin 10 is flush with the cavity surface 2fc of the molding die 4. Then, resin 900C is filled into space 4g via spool 4s. At this time, valve 72 is switched to open to the atmosphere in order to evacuate the air in space 4g during the filling process.

When the filling is completed and the resin molded product 900 is formed by cooling and hardening, as shown in FIG. 5B, the process proceeds to the mold opening process in which the ejector pin 10 is fixed in position relative to the movable mold 2 and the movable mold 2 is moved in a direction away from the fixed mold 3 (step S110). During the mold opening process, the valve 72 remains connected to the atmosphere.

When mold opening is complete, the gas control mechanism 7 operates the valve 72 to switch the connection of the air tube 74 from the atmosphere side to the compressor 71 side, as shown in FIG. 5C, and proceeds to the vacuum breaking process (step S120). In the vacuum breaking process, the compressed air in the high-pressure flow path 73 sent out from the compressor 71 passes through the valve 72 and flows into the flow hole 10h via the air tube 74. The air then passes through the porous portion 11p of the protruding surface portion 11 and is ejected from the protruding surface 10fp.

This allows air to flow between the contact surface 900f and the cavity surface 2fc of the resin molded product 900, creating a gap of 1 mm to 5 mm between the contact surface 900f and the cavity surface 2fc, and releasing the resin molded product 900. The air pressure used here is in the range of 0.3 MPa to 0.8 MPa, and is adjusted depending on the shape of the resin molded product 900, the release distance, etc.

Here, the time it takes for the resin molded product 900 to be released from the cavity surface 2fc (mold release time) is measured, and the time to switch the valve 72 to the atmosphere side is determined based on the measurement result. The ejection start time is delayed by a time equal to the measured mold release time. Alternatively, a method may be used in which a signal is sent to the molding machine after the mold release time has elapsed, and the ejection process is started.

In the ejection process (step S130), as shown in FIG. 6A, the valve 72 is switched to the atmospheric side, and then the ejector plate 5 is driven to eject the ejection surface 10fp of the ejector pin 10 from the cavity surface 2fc. This allows the resin molded product 900 to be completely released and removed from the molding die 4 (movable die 2).

Once the resin molded product 900 has been removed, the process proceeds to the cleaning process (step S200). In the cleaning process, similar to the filling process, the ejector plate 5 is driven so that the protruding surface 10fp of the ejector pin 10 is flush with the cavity surface 2fc, as shown in FIG. 6B. Then, the valve 72 is operated so that the connection destination of the air tube 74 is switched to the compressor 71 side.

The compressed air in the high-pressure flow path 73 sent out from the compressor 71 passes through the valve 72, passes through the air tube 74, flows into the flow hole 10h, passes through the porous portion 11p of the protruding surface portion 11, and is ejected from the protruding surface 10fp. As a result, the gas generated from the resin and trapped in the gas exhaust path is discharged together with the compressed air, so that the gas exhaust path can be cleaned. By performing this cleaning process for each molding shot, it is possible to discharge trapped gas, tar, etc. outside the molding die 4 before they solidify in the gas exhaust path, preventing molding defects due to the accumulation of gas and tar and enabling a significant extension of the maintenance cycle.

In the ejector pin 10 of the present application, a flow hole 10h is formed that penetrates to the flange portion 13 on the opposite side of the protruding surface 10fp in the axial direction, so that the flow hole 10h opens outside the molding die 4 (movable die 2) rather than inside the ejector pin hole 2he. Therefore, even when gas generated during molding is discharged by passing through the protruding surface portion 11, tar and the like do not accumulate in the ejector pin hole 2he and interfere with sliding.

In addition, simply making the protruding surface gas permeable, as in the ejector pin of the non-patent document, can discharge gas generated during molding, but it is difficult to discharge gas, tar, etc. that has accumulated in the gas discharge path. In contrast, in the ejector pin 10 of the present application, the flow hole 10h opened in the flange portion 13 on the opposite side of the protruding surface 10fp in the axial direction is connected to a gas control mechanism 7 that can switch the connection target to either the atmosphere side or the compressor 71 side. Therefore, it becomes possible to discharge gas, tar, etc. before they solidify during the molding process by gas pressure, making it possible to significantly extend the maintenance cycle.

Furthermore, if a vacuum breaking process (FIG. 5C: step S120) is performed in the molding process, in which gas is ejected from the protruding surface portion 11 to push out the resin molded product 900, whitening and deformation of the molded product due to reduced demolding resistance when the molded product is removed is suppressed, and the quality of the resin molded product 900 is improved.

Embodiment 2.
In the above-mentioned embodiment 1, a resin molding was described that utilizes the gas permeability of the protruding surface, which is one of the features of the ejector pin, to facilitate mold release, prevent molding defects due to the accumulation of gas and tar, and significantly extend the maintenance cycle. In the present embodiment 2, an example of operation that utilizes the detachable protruding surface to further extend the maintenance cycle will be described.

Figures 8 to 11 are intended to explain the operation of a molding apparatus using a molding die equipped with an ejector pin according to embodiment 2, and Figure 8 is a schematic diagram showing the state inside a molding apparatus having a gas control mechanism corresponding to Figure 3 of embodiment 1. Also, Figures 9A to 9C and Figures 10A to 10C are schematic diagrams corresponding to Figure 8 showing the state of each step in a maintenance process carried out by a molding apparatus equipped with a molding die equipped with an ejector pin, and Figure 11 is a flowchart for explaining the operation in the maintenance process proceeding in the order of Figures 10A to 10C and Figures 11A to 11C. Note that the configuration of the ejector pin and molding apparatus is the same as in embodiment 1, and explanations of similar parts will be omitted, and the figures used in embodiment 1 will be used.

When carrying out the maintenance method according to the second embodiment, as shown in FIG. 8, a spare part 11S for the protruding surface portion 11 and a cleaning tank 80 for removing gas, tar, etc. that has accumulated on the used protruding surface portion 11 are added to FIG. 3 of the first embodiment. Based on these configurations, the maintenance process after the molding process by the molding device 100 using the ejector pin 10 will be described with reference to the flowchart in FIG. 11.

In the ejection process (FIG. 6A: step S130) described in the first embodiment, the resin molded product 900 is removed, and after the cleaning process (FIG. 6B: step S200), the molding process is stopped by switching the valve 72 to the atmosphere side as shown in FIG. 9A with the molding die 4 open. Then, as a maintenance process, the ejector plate 5 is driven to eject the ejector pin 10 (step S300) as shown in FIG. 9B. Note that the sequence is not limited to the above, and for example, the cleaning process may not be performed and the state in which the resin molded product 900 is removed in the ejection process may be replaced with step S300.

With the ejector pin 10 in the protruding state, as shown in FIG. 9C, the protruding surface portion 11 of the ejector pin 10 is removed, and the removed protruding surface portion 11 is placed in the cleaning tank 80 and cleaned (step S310).

Next, as shown in FIG. 10A, the connection of the valve 72 is switched from the atmosphere side to the compressor 71 side. Then, the compressed air sent out from the compressor 71 is discharged to the outside through the air tube 74, the through hole in the rear plate 52, and the main body 14 (the flow hole 10h), and the gas discharge path is cleaned by air blowing (step S320). This cleans the gas discharge path by discharging the resin-derived gas, tar, etc. that have accumulated in the gas discharge path from the cavity surface 2fc of the molding die 4.

In addition, in the process of cleaning the gas exhaust path, it is not limited to supplying compressed air from the compressor 71, but an organic solvent such as acetone or ethanol may be poured in from a chemical pump (not shown). In this case, in order to remove the poured-in organic solvent, the valve 72 is switched to the compressor 71 side, and air is allowed to flow into the air tube 74, the through hole in the rear plate 52, and the main body 14 (flow hole 10h) to remove the remaining organic solvent.

After the gas exhaust path cleaning process is completed and the air blowing is stopped (step S330), the spare 11S of the protruding surface is fastened to the female thread 12sf of the columnar portion 12 to attach the spare 11S (step S340), as shown in FIG. 10B. Then, as shown in FIG. 10C, the ejector plate 5 is pulled back to return the protrusion of the ejector pin 10 to its original position (step S350).

Here, the gas-permeable protruding surface portion 11, which is prone to clogging, is made detachable by screw fastening, so that the protruding surface portion 11 can be easily replaced with the spare 11S simply by protruding the ejector pin 10 while the molding die 4 is attached to the molding device 100. In other words, replacement due to clogging can be completed in about 20 minutes, making it possible to significantly improve productivity. This makes it possible to clean the protruding surface portion 11 (replace it with a clean spare 11S) and clean the gas exhaust path without removing the molding die 4 from the molding device 100, making maintenance easier and allowing for a significant reduction in maintenance time.

Although the present application describes exemplary embodiments, the various features, aspects, and functions described in the embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Thus, countless variations not illustrated are anticipated within the scope of the technology disclosed in the present specification. For example, this includes cases in which at least one component is modified, added, or omitted.

For example, in each of the above embodiments, the gas control mechanism 7 is provided as part of the molding device 100, but this is not limiting. The gas control mechanism 7 may be a device separate from the molding device 100, and may switch the valve 72 according to the molding process or adjust the timing of the molding process by sending and receiving signals via a communication means or the like.

As described above, the ejector pin 10 of the present application includes a main body 14 having a columnar portion 12 that is inserted into an ejector pin hole 2he of a mold (e.g., movable mold 2) and a flange portion 13 formed on the base side of the columnar portion 12, a disk portion 111 that is connected to the tip of the columnar portion 12 and forms a protruding surface 10fp, and a fastening portion 112 that extends from the surface opposite the protruding surface 10fp of the disk portion 111 and forms a detachable fastening mechanism between the tip (e.g., female screw 12sf), and the inner radial direction The protruding surface portion 11 has a side portion (porous portion 11p) formed of a porous material that allows gas to pass in the axial direction, and the main body portion 14 is configured to have a flow hole 10h formed with one end opening in the radial center portion of the tip portion and the other end opening in the portion exposed from the base side mold (e.g., movable mold 2). This makes it possible to discharge resin-derived gas and tar that has accumulated in the gas discharge path without disassembling the molding mold 4, making maintenance easier and allowing for a significant reduction in maintenance time.

If the fastening mechanism is configured with a male screw 11sm formed in the fastening portion 112 and a female screw 12sf formed in the opening at the tip of the flow hole 10h, the protruding surface portion 11 is mechanically and stably fixed to the main body portion 14, and the protruding surface portion 11 can be easily replaced by protruding the ejector pin 10 from the cavity surface 2fc.

Furthermore, if the protruding surface portion 11 is configured so that the radial outside of the porous material (porous portion 11p) is covered with a dense material (dense portion 11r) that is formed denser than the porous material (porous portion 11p), the reliability as a structural material increases, and in particular, it is possible to achieve both strong fastening and easy removal.

The flow hole 10h is a through hole that passes through the axial center of the main body 14 and opens at the flange 13 at the other end, making it easy to fabricate and also easy to drain because there are no bends where tar or the like can easily become trapped.

In addition, according to the molding device 100 that performs injection molding using a mold (molding mold 4) equipped with the above-mentioned ejector pin 10, the opening at the other end of the flow hole 10h is provided with a gas control mechanism 7 that can be switched between a compressed air supply system (compressor 71, high-pressure flow path 73) and the atmosphere depending on the process in the injection molding. This makes maintenance easy, and when the vacuum is broken, the resin molded product 900 is pushed out from the cavity surface 2fc by air pressure, suppressing whitening and deformation, making it possible to stably manufacture high-quality resin molded products 900.

Furthermore, if the molding method using the mold (molding die 4) equipped with the above-mentioned ejector pin includes a process (step S120) of sending compressed air into the flow hole 10h and letting it flow out from the protruding surface 10fp of the ejector pin 10 when the resin filling into the mold (molding die 4) is completed and the mold is opened, forming a gap between the resin molded product 900 molded by resin filling and the mold (cavity surface 2fc), the resin molded product 900 can be separated from the cavity surface 2fc by air pressure without relying on the protruding ejector pin 10, thereby suppressing whitening and deformation and making it possible to stably manufacture high-quality resin molded products 900.

Furthermore, if the process includes a step (step S200 or step S320) of feeding compressed air into the flow hole 10h after the resin molded product 900 is removed from the mold (molding die 4) and ejecting the compressed air from the protruding surface 10fp of the ejector pin 10 or the opening at the tip of the flow hole 10h, gas and tar derived from the resin that are trapped in the gas exhaust path can be exhausted, making maintenance easier and enabling a significant reduction in maintenance time.

2: Movable mold, 2fc: Cavity surface, 2g: Gas vent, 2he: Ejector pin hole, 10: Ejector pin, 10fp: Protruding surface, 10h: Flow hole, 11: Protruding surface portion, 111: Disk portion, 112: Fastening portion, 11p: Porous portion, 11r: Dense portion, 11sm: Male thread (fastening mechanism), 11S: Spare, 12: Columnar portion, 12sf: Female thread (fastening mechanism), 13: Flange portion, 14: Main body portion, 5: Ejector plate, 51: Front plate, 52: Rear plate, 7: Gas control mechanism, 71: Compressor, 72: Valve, 75: Air coupler, 80: Cleaning tank, 900: Resin molded product, Db: Diameter, Dr: Outer diameter, Dp: diameter, t13: thickness, tm: thickness.

Claims (6)

a main body having a columnar portion to be inserted into an ejector pin hole of a mold and a flange portion formed on a base side of the columnar portion; a disk portion continuing to a tip end of the columnar portion and forming a protruding surface, and a fastening portion extending from a surface of the disk portion opposite to the protruding surface and constituting a detachable fastening mechanism between the tip end and the main body, the radially inner portion being formed of a porous material that is permeable to gas in the axial direction;
a flow hole is formed in the main body, the flow hole having one end opening at a radial center portion of the tip portion and the other end opening at a portion of the base side exposed from the die ;
The ejector pin is characterized in that the radially outer side of the protruding surface portion is covered with a dense material that is denser than the porous material . The ejector pin according to claim 1, characterized in that the fastening mechanism is composed of a male thread formed in the fastening portion and a female thread formed in the opening portion of the tip of the flow hole. 3. The ejector pin according to claim 1 , wherein the communication hole is a through hole that passes through an axial center of the main body and has the other end opened at the flange portion. A molding apparatus for performing injection molding using a mold having the ejector pin according to any one of claims 1 to 3 mounted thereon,
a molding apparatus comprising: a gas control mechanism that can switch between connecting the opening at the other end of the communication hole to a compressed air supply system or to the atmosphere depending on the process in the injection molding. 4. An ejector pin comprising: a main body having a columnar portion to be inserted into an ejector pin hole of a die and a flange portion formed on a base side of the columnar portion; a disk portion connected to a tip end of the columnar portion and forming a protruding surface; and a fastening portion extending from a surface of the disk portion opposite to the protruding surface and constituting a detachable fastening mechanism between the tip end and the main body and having a flow hole formed in the main body and having a flow hole whose one end opens in a radial center portion of the tip end and whose other end opens in a portion exposed from the die on the base side, or a molding method using a die in which the ejector pin according to any one of claims 1 to 3 is mounted,
a step of feeding compressed air into the flow hole and causing it to flow out from the protruding surface of the ejector pin when the resin filling into the mold is completed and the mold is opened, thereby forming a gap between the resin molded product formed by the resin filling and the mold;
A molding method comprising the steps of: a step of feeding compressed air into the flow hole after removing the resin molded product from the mold and ejecting the compressed air from the protruding surface of the ejector pin or an opening at the tip of the flow hole;
The molding method according to claim 5 , further comprising:

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