JP2019214157A - Injection molding die - Google Patents

Abstract

To provide an injection molding die capable of achieving both suppression of burr generation and improvement of degassing efficiency.SOLUTION: An injection molding die 10 has a stationary die 40 having a cavity part 40A into which molten resin is injected from a gate 40G, a movable die 20 closed with the stationary die 40, an accommodation hole 22B opening at a position facing the cavity part 40A on a parting surface 22A of the movable die 20, a gas exhaust path (gas vent hole 22H) opening in a hole wall 22BH of the accommodation hole 22B, and a core member 24A slidably disposed between an open position for opening the gas exhaust path and a closed position for closing the gas exhaust path within the accommodation hole 22B.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mold for injection molding.

  Patent Literature 1 below describes an injection molding device in which a gas vent is communicated with a cavity. In this injection molding apparatus, an exhaust groove is communicated with a gas vent, and a high pressure air is caused to flow through the exhaust groove to generate a negative pressure, thereby removing gas in the cavity.

JP 2004-209814 A

  In the injection molding apparatus of Patent Document 1, the width of the gas vent is formed small in order to suppress the occurrence of burrs on the molded product. Also, if the width of the gas vent is reduced, it becomes difficult for the gas to escape. Therefore, high-pressure air is supplied to the exhaust groove to increase the gas removal efficiency. However, fluid such as high-pressure air is difficult to control, and there is a possibility that degassing performance may not be stable.

  The present invention has been made in view of the above circumstances, and has as its object to provide an injection molding die capable of achieving both suppression of burr generation and improvement of gas removal efficiency.

  The injection mold according to the present invention according to claim 1, wherein a first mold having a cavity through which a molten resin is injected from a gate, a second mold closed with the first mold, and a second mold. A receiving hole that opens at a position facing the cavity on the parting surface of the mold, a gas discharge path that opens to the hole wall of the receiving hole, and an opening position that opens the gas discharge path within the receiving hole, And a core member slidably disposed between a closing position for closing the gas discharge path.

  In the injection molding die according to the first aspect of the present invention, the gas discharge path is opened in the hole wall of the accommodation hole in which the core member is accommodated. The gas discharge path is opened and closed by moving the core member between the open position and the closed position.

  When the molten resin is injected into the cavity with the core member set at the open position, the gas in the cavity is discharged from the gas discharge path. When the core member is slid to the closing position when a predetermined amount of the molten resin has been injected, the gas discharge path is closed, and the space surrounded by the cavity and the core member is filled with the resin.

  The gas discharge path does not open to the cavity or the core member. For this reason, even if the opening width is made larger than that of the gas vent opening into the cavity in order to improve the efficiency of degassing, burrs in the gas discharge path do not occur in the resin molded product.

  3. The injection molding die according to claim 2, wherein the receiving hole and the cavity have the same shape when the parting surface is viewed from the front, and the hole wall through which the gas discharge path opens. Is the hole wall at the position farthest from the gate.

  In the injection mold according to the second aspect of the present invention, the receiving hole and the cavity have the same shape when the parting surface is viewed from the front, and gas is discharged to the hole wall at the position farthest from the gate. The path is open. For this reason, the path from the gate to the gas discharge path is longer than when the gas discharge path is opened on the hole wall near the gate. Thereby, a large amount of resin can be injected while degassing before moving the core member to the closed position.

  In the injection mold according to the third aspect of the present invention, the gas discharge path is open over the entire width of the hole wall.

  In the injection molding die according to the third aspect of the present invention, since the gas discharge path is open over the entire width of the hole wall, that is, the gas discharge path is provided over the entire width of the cavity. A path has been formed. Thereby, for example, the opening area is larger and the gas removal efficiency is higher than when the gas discharge path is formed only in a part of the cavity in the width direction.

  According to a fourth aspect of the present invention, the gas discharge path is inclined in a direction away from the parting surface toward a downstream side from an opening end.

  In the injection molding die according to the present invention, the thickness of the die between the gas discharge path and the parting surface increases from the opening end of the gas discharge path to the downstream side. This makes it easier to secure the rigidity of the parting surface, for example, even if the gas discharge path is made wider than in the case where the gas discharge path is not inclined.

  The injection molding die according to the present invention has an excellent effect that both suppression of burr generation and improvement of degassing efficiency can be achieved.

It is a sectional view showing an example of an injection-molding metallic mold concerning an embodiment of the present invention. FIG. 3 is a front view of a parting surface of a movable mold in the injection mold according to the embodiment of the present invention. It is sectional drawing which shows the state which has set the decorative film in the metal mold | die for injection molding which concerns on embodiment of this invention. It is sectional drawing which shows the state which closed the mold for injection molding which concerns on embodiment of this invention. (A) is a partial enlarged sectional view showing a state in which a resin is injected into a cavity in a state where a core portion is in an open position in an injection mold according to an embodiment of the present invention, and (B) is a core. It is a partial expanded sectional view showing the state where a part was moved to a closure position. It is sectional drawing which shows the state which moved the core part to the closing position in the metal mold | die for injection molding which concerns on embodiment of this invention. It is sectional drawing which shows the state which opened the metal mold | die for injection molding which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view illustrating a state in which a molded product is released from the injection molding die according to the embodiment of the present invention. It is a top view showing the modification in which the gas discharge hole was formed in a part of the width direction of the accommodation hole in the metal mold for injection molding concerning the embodiment of the present invention. It is sectional drawing which shows the modification which inclined the gas discharge hole toward the direction away from a parting surface in the injection mold which concerns on embodiment of this invention. FIG. 7 is a partially enlarged cross-sectional view showing a modification in which the sizes of the core and the cavity are changed in the injection mold according to the embodiment of the present invention.

(Injection mold)
As shown in FIG. 1, a mold for injection molding (hereinafter, referred to as “mold 10”) according to an embodiment of the present invention includes a movable mold 20 and a fixed mold 40. The fixed mold 40 is an example of a first mold in the present invention, and the movable mold 20 is an example of a second mold in the present invention.

(Movable type)
The movable mold 20 includes a main body 22, two plates 24 and 26 installed inside the main body 22, and ejector rods 24 </ b> L and 26 </ b> L that press the plates 24 and 26 toward the fixed mold 40, respectively. Have.

  The main body 22 includes a parting surface 22A facing the fixed mold 40 and in contact with the parting surface 40D of the fixed mold 40 when the mold is closed, an accommodation hole 22B opened in the parting surface 22A, and a movable mold 20 when the mold is closed. And a guide pin 22C for positioning with respect to the fixed die 40. A gas vent hole 22H is opened in the hole wall of the housing hole 22B. The gas vent hole 22H is formed over the entire width (width H1) of the hole wall of the accommodation hole 22B, as shown by a shaded region in FIG. The gas vent hole 22H extends parallel to the parting surface 22A as shown in FIG.

  A space 22V is formed inside the main body 22, and the space 22V is divided into two spaces 22VA and 22VB by a partition plate 22D. The space 22VA is a space arranged closer to the fixed mold 40 than the space 22VB. Plates 24 and 26 are installed in the spaces 22VA and 22VB, respectively.

  The plate 24 is integrally formed with a core member 24A whose entire outer peripheral portion is slidable with the accommodation hole 22B. As shown in FIG. 2, when the parting surface 22A is viewed from the front, the core member 24A has a rectangular shape having a width H1 and a depth D1, and has the same shape as a cavity portion 40A described later.

  The plate 24 is urged by the coil spring 30A in a direction away from the fixed mold 40, and is pressed against the partition plate 22D with the gas vent hole 22H opened. Thereby, the surface (core surface 24AE) of core member 24A is arranged at a position recessed from parting surface 22A. In the following description, with respect to the position of the core member 24A, the position shown in FIG. 1 (the position where the gas vent hole 22H is exposed) is referred to as an "open position".

  Further, the plate 24 is pressed in a direction approaching the fixed mold 40 by the ejector rod 24L. Then, the gas vent hole 22H is closed at a position where it comes into contact with the spacer 32A, and the surface AE of the core member 24A is substantially flush with the parting surface 22A (see, for example, FIG. 6). In the following description, with respect to the position of the core member 24A, the position shown in FIG. 6 (the position at which the gas vent hole 22H is closed) is referred to as a "closed position".

  A release pin 26A is integrated with the plate 26. The release pin 26 </ b> A protrudes from the plate 26 toward the fixed mold 40 and is inserted into a through hole formed in the main body 22. Except at the time of releasing the molded product CR (see FIG. 8), the distal end surface of the release pin 26A is arranged at a position recessed from the parting surface 22A.

  Further, guide pins 26B are integrated with the plate 26. The guide pins 26B protrude from the plate 26 toward the fixed mold 40, and are inserted into through holes formed in the partition plate 22D and the plate 24.

  A coil spring 30B is wound around the guide pin 26B. The coil spring 30B urges the plate 26 in a direction away from the fixed die 40. The plate 26 urged by the coil spring 30 </ b> B abuts on the spacer 32 </ b> B, thereby restricting movement of the plate 26 away from the fixed mold 40. The urging force of the coil spring 30B is weaker than the urging force of the coil spring 30A. Thereby, the state where the plate 24 is pressed by the partition plate 22D is maintained.

  Further, the plate 26 is pressed in a direction approaching the fixed mold 40 by the ejector rod 26L. Then, at the position where it comes into contact with the spacer 32C, the tip of the release pin 26A protrudes from the parting surface 22A (for example, see FIG. 8).

(Fixed type)
The fixed mold 40 has a cavity 40A, a runner 40B and a spool 40C. The cavity portion 40A is a concave portion formed on the parting surface 40D, and is formed to be concave in a direction away from the movable mold 20.

  The runner section 40B is a supply path for allowing the molten resin injected from the spool section 40C to flow into the cavity section 40A, and has a planar shape along the width direction of the cavity section 40A as shown by a two-dot chain line in FIG. Is formed. In FIG. 2, the runner portion 40B and the spool portion 40C are indicated by two-dot chain lines. However, since the cavity portion 40A has the same shape as the core member 24A when the parting surface 22A is viewed from the front, the outer shape is reduced. The illustration of the lines is omitted.

  The connection between the cavity 40A and the runner 40B is referred to as a gate 40G. The hole wall 22BH in which the gas vent hole 22H is formed in the movable mold 20 is located farthest from the gate 40G in the fixed mold 40 as compared with the other hole walls. That is, when the molten resin is injected from the gate 40G to the cavity 40A, the gas vent hole 22H is formed at a position located on the most downstream side.

  Guide holes 40E are formed in the parting surface 40D at positions corresponding to the guide pins 22C of the movable mold 20, respectively. Thereby, the movable mold 20 is positioned at a predetermined position with respect to the fixed mold 40.

(Method of manufacturing molded products)
An example of a method for manufacturing a molded product CR (see FIG. 8) using the mold 10 according to the embodiment of the present invention will be described. In order to obtain the molded product CR, first, as shown in FIG. 3, the decorative films 50A and 50B are installed on the core surface 24AE and the cavity 40A, respectively. Then, the movable mold 20 is moved in a direction in which the movable mold 20 approaches the fixed mold 40, and the mold is closed, so that the state shown in FIG. 4 is obtained.

  At this time, the movable die 20 is positioned with respect to the fixed die 40 by fitting the guide pins 22C into the guide holes 40E. A chamfer (R surface or C surface) is formed at the tip of the guide pin 22C. This chamfer is a guide portion for introducing the guide pin 22C into the guide hole 40E.

  In this state, as shown in FIG. 4, a runner space L, which is a space filled with the molten resin, is formed between the parting surface 22A of the movable mold 20 and the runner portion 40B of the fixed mold 40. Further, a cavity space C1 which is a space filled with the molten resin is formed in a portion surrounded by the core surface 24AE of the movable mold 20, the accommodation hole 22B, and the cavity 40A of the fixed mold 40.

  The cavity space C1 is a space formed between the fixed mold 40 and the movable mold 20 when the core member 24A is at the “open position”, and the cavity space C1 has a gas vent hole 22H.

  In this specification, “cavity part 40A”, “runner part 40B”, and “spool part 40C” are names of parts formed on fixed mold 40. The “cavity space C1”, the “runner space L”, and the “spool space S” are formed by the “cavity portion 40A, the accommodation hole 22B and the core surface 24AE”, the “runner portion 40B”, and the “spool portion 40C”, respectively. Space. Further, the resins filled in the “cavity space C”, “runner space L” and “spool space S” are referred to as “molded product CR”, “runner resin LR” and “spool resin SR”, respectively.

  As shown in FIG. 5A, when the molten resin is injected into the cavity space C1, the molten resin moves from the gate 40G to the gas vent hole 22H. At this time, gas volatilized from the air and the molten resin in the cavity space C1 is discharged to the gas vent hole 22H.

  When a predetermined amount of the molten resin is injected, the core member 24A is moved to the “closed position” as shown in FIG. In order to move the core member 24A to the “closed position”, as shown in FIG. 6, the plate 24 is pressed in a direction approaching the fixed mold 40 by operating the ejector rod 24L. Thereby, the gas vent hole 22H is closed, and a cavity space C2 filled with the molten resin is formed in a portion surrounded by the core surface 24AE and the cavity portion 40A.

  After the resin is solidified, the fixed mold 40 and the movable mold 20 are opened as shown in FIG. Then, as shown in FIG. 8, the ejector rod 26L is operated to press the plate 26 in a direction approaching the fixed mold 40. As a result, the release pin 26A protrudes from the parting surface 22A, and the molded product CR, the runner resin LR, the spool resin SR, and the decorative films 50A and 50B are integrally released from the movable mold 20. The runner resin LR and the spool resin SR are cut from the molded product CR after release. Through the above steps, a molded product CR in which the decorative films 50A and 50B are integrally molded is obtained.

(Action / Effect)
In the injection molding die (mold 10) according to the embodiment of the present invention, as shown in FIG. 1, a gas vent hole 22H is opened in a hole wall of a housing hole 22B in which a core member 24A is housed. The gas vent hole 22H is opened and closed when the core member 24A moves between the open position (see FIG. 5A) and the closed position (see FIG. 5B) in the mold closed state. .

  As a result, the gas vent hole 22H does not open to the cavity 40A or the core member 24A that forms the molded product CR (see FIG. 8). In other words, the gas vent hole 22H does not open into the cavity space C2. For this reason, for example, even if the opening height (width H1 shown in FIG. 2 and height T shown in FIG. 5A) is increased as compared to the gas vent opening in the cavity, the molded product CR has a gas vent hole 22H. No burr occurs.

  That is, in the present embodiment, the gas vent hole 22H is formed over the entire width (width H1) of the cavity portion 40A and the housing hole 22B, and a large opening area is secured to increase the gas venting efficiency. However, no burr is generated in the molded product CR by the gas vent hole 22H.

  Further, since the opening area of the gas vent hole 22H is large, the internal pressure in the cavity space C1 at the time of filling the molten resin becomes low. As a result, internal stress does not easily occur in the filled resin, so that moldability is improved.

  Note that the opening height T of the gas vent hole 22H is preferably larger (for example, 1 mm or more) than the opening height (for example, 0.002 to 0.02 mm) of a known gas vent in order to enhance gas venting efficiency. Furthermore, since no burrs are generated, the height of the molded product CR can be made approximately the same as that of the molded product CR.

  Further, in the mold 10, as shown in FIG. 1, a gas vent hole 22H is opened at a position farthest from the gate 40G in the hole wall of the accommodation hole 22B accommodating the core member 24A. Specifically, as shown in FIG. 2, a gas vent hole 22H is opened in a hole wall 22BH at a position facing the gate 40G in the hole wall of the accommodation hole 22B.

  Therefore, the path from the gate 40G to the gas vent hole 22H is longer than in the case where the gas vent hole 22H is opened in the hole wall near the gate 40G. Thereby, before moving the core member 24A to the closing position, a large amount of resin can be injected while degassing.

  In the present embodiment, the decorative films 50A and 50B are set in the core member 24A and the cavity 40A, respectively, and injection-molded. The decorating films 50A and 50B contain a printing solvent and moisture, but the amount and location of volatilization of these solvents and moisture vary depending on the degree of decorating (print density, area, position, etc.).

  For this reason, even if a gas vent having a small opening area is provided, there is a possibility that the gas cannot be appropriately vented. However, the gas vent hole 22H in the present embodiment can have a large opening area, so that gas venting is easy. Further, since it is less necessary to consider the amount of generated gas, it is easy to select a solvent used for decoration. Further, since the degassing efficiency is high, the residue hardly adheres to the cavity 40A and the core member 24A. Thus, the frequency of cleaning the mold 10 can be reduced. Note that the decorative films 50A and 50B may be omitted as appropriate.

  In the mold 10, the core member 24A is moved to open and close the gas vent hole 22H. For this reason, by appropriately controlling the movement timing and speed of the core member 24A, it is possible to appropriately control the gas discharge.

  In the present embodiment, the gas vent hole 22H is formed over the entire width direction (width H1) of the cavity 40A and the housing hole 22B, but the embodiment of the present invention is not limited to this. For example, like the gas vent hole 22HA shown in FIG. 9, the gas vent hole 22HA may be formed only in a part of the width of the accommodation hole 22B. By doing so, since the thin portion formed between the parting surface 22A and the gas vent hole 22HA in the movable mold 20 is reduced, the rigidity of the parting surface 22A of the movable mold 20 is increased.

  In addition, from the viewpoint of increasing the rigidity of the parting surface 22A, for example, in a direction away from the parting surface 22A toward the downstream side of the gas path from the opening end of the storage hole 22B, such as a gas vent hole 22HB shown in FIG. It may be inclined. By forming the gas vent hole in this manner, for example, even if the gas vent hole is formed over the entire width direction (width H1) of the housing hole 22B, the rigidity of the parting surface 22A does not easily decrease.

  Further, the gas vent hole 22HB inclined from the opening end of the accommodation hole 22B in a direction away from the parting surface 22A toward the downstream side of the gas path from the opening end of the accommodation hole 22B like the gas vent hole 22HA. May be inclined toward the downstream side of the parting surface 22A.

  In the present embodiment, the core member 24A and the cavity portion 40A have the same shape when the parting surface 22A is viewed from the front, but the embodiment of the present invention is not limited to this. For example, the core member 24B and the cavity portion 40F shown in FIGS. 11A and 11B may be formed in different shapes. In this case, the dimensional difference (D3-D2) between the cavity portion 40F and the core member 24B is preferably adjusted, for example, so that the thickness of the molded product CR1 to be molded is uniform (thickness t1 = thickness t2).

  Further, in the present embodiment, the gas vent hole 22H is opened at a position farthest from the gate 40G in the hole wall of the housing hole 22B in which the core member 24A is housed, but the embodiment of the present invention is not limited thereto. Not exclusively. For example, the gas vent hole may be opened in the hole wall of the accommodation hole 22B other than the hole wall 22BH at the position facing the gate 40G.

  Further, in the present embodiment, the movable mold 20 is moved with respect to the fixed mold 40, but the embodiment of the present invention is not limited to this. For example, the movable die 20 may be configured not to move (fixed type), and the fixed die 40 may be moved (movable type). Thus, the present invention can be implemented in various aspects.

10 Mold for injection molding 20 Movable mold (second mold)
22A Parting surface 22B Housing hole 22BH Hole wall 22H Gas release hole (gas discharge path)
22HA Gas vent hole (gas discharge path)
22HB gas vent hole (gas discharge path)
24A core member 24B core member 40 fixed type (first type)
40G Gate 40F Cavity (cavity)
40A cavity (cavity)

Claims (4)

A first mold having a cavity from which a molten resin is injected from a gate,
A second mold closed with the first mold,
A receiving hole that opens at a position facing the cavity on the parting surface of the second mold,
A gas discharge path that opens in the hole wall of the accommodation hole,
In the accommodation hole, a core member slidably disposed between an open position for opening the gas discharge path and a closed position for closing the gas discharge path,
Injection mold equipped with. The accommodation hole and the cavity have the same shape when the parting surface is viewed from the front,
The injection mold according to claim 1, wherein the hole wall where the gas discharge path is opened is a hole wall located farthest from the gate. The gas discharge path is open over the entire width of the hole wall,
The injection mold according to claim 1 or 2.   The injection mold according to any one of claims 1 to 3, wherein the gas discharge path is inclined in a direction away from the parting surface toward the downstream side from the opening end.