JP6730039B2 - Mold for molding - Google Patents

Description

The present invention relates to a molding die.

A molding die for molding a molded product such as a resin material (hereinafter, simply referred to as a mold) has a first molding die and a second molding die that define a molding portion. When injection molding is performed using the above-described mold, first, a melted resin material (molding material) is injected into the molding portion through the gate opening. After that, by solidifying the resin material, a molded product having an outer shape following the inner surface shape of the molded portion is molded.

In the mold described above, the gate method is selected according to various conditions such as the shape of the molded product, the type of resin material, and the molding conditions. One of the gate methods is the pin gate method. In the pin gate method, a gate opening extending in the movement direction is formed in a portion of the first molding die that faces the second molding die in the movement direction of the first molding die and the second molding die (for example, the following Patent Documents). 1).

Japanese Patent Laid-Open No. 8-197583

However, in the configuration of Patent Document 1 described above, there is still room for improvement in terms of improving the filling property of the resin material into the molding portion. Specifically, in the configuration of Patent Document 1 described above, since the gate opening extends linearly along the movement direction, the resin material is injected toward the bottom surface of the molding portion. Then, the resin material injected from the gate opening into the molding portion flows toward the bottom surface of the molding portion and then spreads to the outer peripheral side of the molding portion. Therefore, especially when the molded product is in the shape of a thin plate (the shape in which the dimension in the direction orthogonal to the moving direction is larger than the dimension in the moving direction), the resin material injected from the gate opening fills up to the outer peripheral side of the molding part. Hard to be done.
In this case, the packing density of the resin material on the outer peripheral side of the molding portion tends to be lower than the packing density of the resin material on the periphery of the gate opening. When the density distribution of the resin material becomes nonuniform in the molding portion, the molded product is likely to warp or deform.

Further, in the configuration of Patent Document 1, since the gate opening extends linearly along the moving direction, the resin material collides with the portion of the bottom surface of the molding portion that faces the gate opening in the moving direction. Large pressure acts when doing. As a result, the bottom surface of the molded portion is easily damaged locally.

Therefore, the present invention has been made in view of the above circumstances, and provides a molding die capable of molding a molded product with high accuracy by improving the mold life while improving the mold life.

In order to solve the above-mentioned problems, a molding die according to an aspect of the present invention is configured to be relatively contactable with and separable from a first molding die and the first molding die, and A second molding die that defines a molding portion between the first molding die and the second molding die, the second molding die extending in a direction intersecting a moving direction of the first molding die and the second molding die, and A first gate opening is formed at a portion of the portion facing the second mold in the moving direction.

According to this aspect, the molding material that flows into the molding portion through the first gate opening flows so as to spread to the outer peripheral side of the molding portion, and thus it becomes easy to uniformly supply the molding material to the entire molding portion. Thereby, the density distribution of the resin material in the molding portion can be made uniform, and the filling property of the resin material can be improved. As a result, a highly accurate molded product with less warpage and deformation can be molded.
Further, it is possible to prevent the bottom surface of the molding portion from being locally damaged as compared with the configuration in which the molding material is linearly supplied toward the bottom surface of the molding portion along the moving direction. Thereby, the mold life can be improved.
Further, since the first gate opening extends in the direction intersecting the movement direction, the filling direction of the molding material is changed according to the position of the first gate opening. In this case, the filling direction of the molding material can be controlled by, for example, arranging the first gate openings so that the molding material flows in a specific direction on the outer peripheral side of the molding portion in a concentrated manner. Can be further improved.

In the above aspect, the first gate opening is opened at a position of the first molding die projecting toward the second molding die side in the moving direction with respect to a mating surface with the second molding die. Good.
According to this aspect, the inclination angle of the first gate opening with respect to the moving direction can be made larger than that in the case where the first gate opening is formed on the mold matching surface. As a result, the molding material can be effectively filled into the outer peripheral side of the molding portion.

In the above aspect, a gate bush may be detachably attached to the first molding die, and the first gate opening may be formed in the gate bush.
According to this aspect, by forming the gate bush separately from the first mold, the first gate opening can be easily processed. Further, for example, when it is necessary to replace the first gate opening due to friction with the molding material, only the gate bush needs to be replaced, so that the maintainability can be improved.

In the above aspect, the first gate opening may have a flow passage cross-sectional area that gradually decreases toward the downstream side in the flow direction.
According to this aspect, the opening edge of the first gate opening can be formed at a sharper angle than in the case where the flow path cross-sectional area of the first gate opening is formed uniformly. As a result, in the gate cutting step, a larger shearing force acts on the connecting portion between the molded product and the gate portion. Therefore, the gate cutting process can be smoothly performed, and the gate residue of the molded product can be reduced.

In the above aspect, the first molding die is formed with a second gate opening extending in the moving direction and opening at a portion of the first molding die facing the second molding die in the moving direction. May be.
According to this aspect, by supplying the molding material through the second gate opening, the resin material can be more uniformly supplied over the entire molding portion. In this aspect, since the first gate opening is formed as described above, the resin material passing through the second gate opening can be removed as compared with the conventional case where the resin material is supplied only from the second gate opening. Can be reduced. Therefore, it is possible to prevent the bottom surface of the molding portion from being locally damaged by the resin material supplied from the second gate opening.

According to the present invention, it is possible to mold a molded product with high precision by improving the mold life while improving the filling property of the resin material.

It is sectional drawing of the metal mold|die in embodiment of this invention. It is an enlarged view corresponding to the II section of FIG. It is an expansion perspective view of a gate bush. FIG. 6 is a process diagram for explaining the gate cutting process, which is a cross-sectional view corresponding to FIG. 1. FIG. 6 is a process diagram for explaining the mold opening process, which is a cross-sectional view corresponding to FIG. 1. It is a process drawing for explaining the taking-out process, and is a cross-sectional view corresponding to FIG. It is an expansion perspective view of a gate bush for explaining the 1st modification of an embodiment. It is an expansion perspective view of a gate bush for explaining the 2nd modification of an embodiment. It is an expansion perspective view of a gate bush for explaining the 3rd modification of an embodiment.

Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view of a mold 1 according to an embodiment of the present invention.
As shown in FIG. 1, a mold (molding die) 1 is a first molding die 10 and a second molding die configured to be movable relative to the first molding die 10 in the Z direction (moving direction). And a mold 20. In this embodiment, the first mold 10 is a fixed mold, and the second mold 20 is a movable mold that comes into contact with and separates from the first mold 10. Further, in the following description, the first molding die 10 side in the Z direction may be referred to as an upper side, and the second molding die 20 side may be referred to as a lower side.

The second molding die 20 is arranged to face the first molding die 10 in the Z direction. A molding recess 23 is formed on a mating surface 21 of the second molding die 20 with the first molding die 10. The molding recess 23 is recessed downward with respect to the mold matching surface 21.

The first molding die 10 has a molding mating surface 11 that closes the molding recess 23 of the second molding die 20 and abuts on the molding mating surface 21 of the second molding die 20 during mold clamping. The space surrounded by the first molding die 10 (mold matching surface 11) and the molding recess 23 of the second molding die 20 defines a molding portion C for molding the molded product S. .. The molded product S of the present embodiment is in the form of a thin plate having a thickness direction in the Z direction, for example.

A holding hole 14 is formed in the first mold 10 so as to penetrate the first mold 10 in the Z direction. The gate bush 13 is detachably mounted in the holding hole 14.

FIG. 2 is an enlarged view corresponding to part II of FIG.
As shown in FIG. 2, the holding hole 14 is formed in a multistage shape in which the inner diameter is reduced as it goes downward. Specifically, the holding hole 14 has a large diameter portion 14a and a small diameter portion 14b continuous with the large diameter portion 14a from below.
The inner diameter of the large diameter portion 14a is formed uniformly over the entire Z direction. A stopper surface 14c is formed on the lower end edge of the large diameter portion 14a so as to project to the inner peripheral side of the large diameter portion 14a.

The upper end edge of the small diameter portion 14b is continuous with the inner peripheral edge of the stopper surface 14c. The upper end of the small diameter portion 14b is a tapered portion 14d whose inner diameter gradually decreases as it goes downward. The lower end of the small diameter portion 14b is connected to the lower end edge of the tapered portion 14d. The lower end opening of the small diameter portion 14b is open inside the molding portion C. In the illustrated example, the lower end opening of the small diameter portion 14b faces the bottom surface of the molding recess 23 in the Z direction.

The gate bush 13 has an axis O extending in the Z direction and is formed in a multi-stage tubular shape that follows the shape of the inner surface of the holding hole 14 described above. The gate bush 13 supplies the molten resin material (molding material) supplied from a supply source (not shown) into the molding section C. Specifically, the gate bush 13 has a bush body portion 31 and a nozzle portion 32 protruding downward from the bush body portion 31.
The bush body 31 is fitted in the large diameter portion 14 a of the holding hole 14. In this case, the lower end surface of the bush main body 31 is close to or in contact with the stopper surface 14c of the holding hole 14 from above.

FIG. 3 is an enlarged perspective view of the gate bush 13.
As shown in FIGS. 2 and 3, the nozzle portion 32 is formed to have a smaller diameter than the bush main body portion 31. The nozzle portion 32 is fitted in the small diameter portion 14 b of the holding hole 14 in a state where the lower end portion thereof projects downward (inside the molding portion C) from the lower end opening portion of the holding hole 14. The upper end portion of the nozzle portion 32 is an upper taper portion 33 whose diameter gradually decreases as it goes downward. The upper taper portion 33 faces the taper portion 14d of the holding hole 14 when the gate bush 13 is mounted in the holding hole 14. In addition, a portion of the nozzle portion 32 that protrudes from the holding hole 14 is a lower taper portion 34 that gradually decreases in diameter as it goes downward.

A gate hole 35 extending in the Z direction is formed in the gate bush 13 described above. The gate hole 35 is formed across the bush body portion 31 and the nozzle portion 32 of the gate bush 13. In the illustrated example, the upper end of the gate hole 35 is open at the upper end surface of the bush body 31. On the other hand, the lower end portion of the gate hole 35 ends in the nozzle portion 32. The gate hole 35 is gradually reduced in diameter as it goes downward.

The nozzle portion 32 described above is formed with a plurality of gate openings (main gate 41 and sub-gate 42) that communicate the gate hole 35 with the inside of the molding portion C.
The main gate (second gate opening) 41 has a circular cross section orthogonal to the flow direction (Z direction) of the resin material. The main gate 41 extends downward from the lower end of the gate hole 35. The lower end of the main gate 41 opens downward at the lower end surface of the nozzle portion 32. That is, the main gate 41 faces the bottom surface of the molding portion C in the Z direction. In the present embodiment, the flow passage cross-sectional area of the main gate 41 is smaller than that of the gate hole 35. Further, the flow passage cross-sectional area of the main gate 41 is formed uniformly over the entire area in the flow direction. However, the flow passage cross-sectional area of the main gate 41 may be gradually reduced toward the lower side (downstream side in the flow direction).

The sub-gate (first gate opening) 42 has a circular cross section orthogonal to the flow direction. The sub-gates 42 extend radially (four in the illustrated example) with respect to the axis O in a plan view viewed from the Z direction. Each sub-gate 42 has an axis O (Z direction) in a sectional view along the Z direction.
It extends in the direction intersecting with. Specifically, each sub-gate 42 extends in a direction away from the axis O (outward in the radial direction) as it goes downward. Each sub-gate 42 is opened on the outer peripheral surface ( side surface portion ) of the lower taper portion 34 in a direction intersecting the axis O. In this case, each sub-gate 42 is oriented toward the outer peripheral side of the molding portion C.

In addition, the flow path cross-sectional area of each sub-gate 42 is formed uniformly over the entire flow direction. However, the flow path cross-sectional area of each sub-gate 42 may be gradually reduced toward the lower side (downstream side in the flow direction). Further, the number of each sub-gate 42 can be changed appropriately. Further, in the example of FIG. 2, the flow passage cross-sectional area of the sub-gate 42 is smaller than the flow passage cross-sectional area of the main gate 41. Further, in the example of FIG. 2, the main gate 41 and the sub-gate 42 are entirely projected below the mold matching surface 11, but at least a part thereof may be positioned below the mold matching surface 11.

In the present embodiment, a runner molding die (not shown) is arranged above the first molding die 10. The runner forming die has a runner hole that connects between the gate hole 35 of the gate bush 13 and the supply source of the resin material. The runner molding die is configured to be movable in the Z direction relative to the respective molding dies 10 and 20.

[Injection molding method]
Next, a method of manufacturing the molded product S using the mold 1 described above will be described.
First, as shown in FIGS. 1 and 2, the first molding die 10 and the second molding die 20 are clamped (mold clamping step). In the mold clamping step, the second molding die 20 is made to approach the first molding die 10 along the Z direction until the mold mating surfaces 11, 21 of the respective molding dies 10, 20 come into contact with each other in the Z direction. As a result, the molding portion C is defined by the mold matching surface 11 of the first molding die 10 and the molding recess 23 of the second molding die 20.

Next, the molten resin material is filled in the molding portion C (filling step). Specifically, the resin material supplied from a supply source (not shown) flows into the gate hole 35 of the gate bush 13 through the runner hole of the runner forming die described above. The resin material that has flowed into the gate hole 35 flows downward in the gate hole 35. After that, the resin material flows into the molding portion C through the gates 41 and 42 of the nozzle portion 32. At this time, among the resin materials, the resin material passing through the main gate 41 flows in the main gate 41 along the Z direction and then flows into the molding portion C toward the bottom surface of the molding recess 23 (in FIG. 2). Arrow M). On the other hand, among the resin materials, the resin material passing through each sub-gate 42 flows into each of the sub-gates 42 in a direction intersecting the Z direction, and then flows into the molding portion C toward the outer peripheral side of the molding portion C (FIG. (See arrow N in 2). As a result, the molding material C is filled with the resin material.

Then, the mold 1 is cooled to solidify the resin material (solidification step). Thereby, the resin molded body 51 corresponding to the inner surface shape of the mold 1 is molded. That is, the resin molded body 51 is one in which the molded product S molded by the molding portion C and the gate portion G molded by the gate bush 13 are integrally formed.

FIG. 4 is a process diagram for explaining the gate cutting process and is a cross-sectional view corresponding to FIG. 1.
As shown in FIG. 4, the resin molded body 51 is cut between the gate portion G and the molded product S (gate cutting step). In the gate cutting step, the molding dies 10 and 20 are moved downward with respect to the runner molding dies while the molding dies 10 and 20 are clamped. Then, the molded product S moves downward with respect to the gate portion G, so that the molded product S is pulled downward with respect to the gate portion G. As a result, the resin molded body 51 is cut between the gate portion G and the molded product S. In particular, in the portion of the connection between the molded product S and the gate portion G, which is located inside the sub-gate 42, the portion of the opening edge of the sub-gate 42 which is located above the gate portion G (upper end opening in FIG. 2). A shearing force acts in the Z direction from the edge 42a). As a result, the gate can be cut smoothly.

FIG. 5 is a process diagram for explaining the mold opening process and is a cross-sectional view corresponding to FIG. 1.
Next, as shown in FIG. 5, in the mold opening step, the second molding die 20 is moved downward with respect to the first molding die 10. As a result, the second molding die 20 is separated from the first molding die 10 while the molded product S is held in the molding recess 23.

FIG. 6 is a process diagram for explaining the taking-out process and is a cross-sectional view corresponding to FIG. 1.
As shown in FIG. 6, in the take-out step, the molded product S is taken out from the molding concave portion 23 of the second molding die 20 using an ejector pin or the like (not shown).
With the above, the molded product S is completed.

As described above, in the present embodiment, the sub-gate 42 extending in the direction intersecting the Z direction is formed in the portion of the first molding die 10 facing the second molding die 20 in the Z direction.
According to this configuration, the resin material flowing into the molding portion C through the sub-gate 42 flows so as to spread to the outer peripheral side of the molding portion C, so that the resin material can be easily uniformly supplied to the entire molding portion C. Thereby, the density distribution of the resin material in the molding portion C can be made uniform, and the filling property of the resin material can be improved. As a result, a highly accurate molded product S with less warpage and deformation can be molded.
Further, compared to a configuration in which the resin material is linearly supplied in the Z direction toward the bottom surface of the molding portion C, the bottom surface of the molding portion C can be suppressed from being locally damaged. Thereby, the mold life can be improved.

Since the sub-gate 42 extends in the direction intersecting the axis O (Z direction), the filling direction of the resin material is changed according to the position of the sub-gate 42. In this case, the filling direction of the resin material can be controlled by, for example, laying out the sub-gates 42 so that the resin material can be concentratedly flowed in a specific direction on the outer peripheral side of the molding portion C. Further improvement can be achieved.

In the present embodiment, the sub-gate 42 is opened at a position projecting downward with respect to the mold matching surface 11 of the first molding die 10 with the second molding die 20.
According to this configuration, the inclination angle of the sub gate 42 with respect to the Z direction can be made larger than that in the case where the sub gate 42 is formed on the mold matching surface 11. Thereby, the outer peripheral side of the molding portion C can be effectively filled with the resin material.

In this embodiment, the gate bush 13 is detachably attached to the first mold 10.
According to this configuration, by making the gate bush 13 separate from the first molding die 10, the gate hole 35 and the gates 41 and 42 can be easily processed. Further, for example, when it is necessary to replace the gates 41 and 42 due to friction with the resin material, only the gate bush 13 needs to be replaced, so that the maintainability can be improved.

In the present embodiment, since the plurality of gates 41 and 42 are provided, the resin material supplied into the molding portion C can be dispersed in the respective gates 41 and 42. As a result, the shear rate of the resin material passing through each gate 41, 42 can be reduced as compared with the case where the resin material passes through one gate. Therefore, wear on the inner surfaces of the gates 41, 42 due to friction with the resin material can be suppressed, and the life of the mold can be improved.

In the present embodiment, since the main gate 41 extending in the Z direction is formed in the gate bush 13, it becomes easy to supply the resin material to the central portion of the molding portion C. Therefore, the resin material can be supplied more uniformly over the entire molding portion C. In the present embodiment, since the sub-gate 42 is formed as described above, the resin material passing through the main gate 41 can be reduced as compared with the conventional case where the resin material is supplied only from the main gate 41. Therefore, it is possible to prevent the bottom surface of the molding portion C from being locally damaged by the resin material supplied from the main gate 41.

Next, a modified example of this embodiment will be described. In each modification, the layout and shape of each gate formed on the gate bush is different from that of the above-described embodiment. In the following description, the same components as those in the above-described embodiment will be designated by the same reference numerals and the description thereof will be omitted.
(First modification)
FIG. 7 is an enlarged perspective view of the gate bush 100 for explaining the first modified example of the present embodiment.
In the gate bush 100 shown in FIG. 7, only the above-described sub gate (first gate opening) 42 is formed in the nozzle portion 32. That is, the main gate 41 (see FIG. 3) described above is not formed in the gate bush 100 of this modification. In the example shown in FIG. 7, six sub-gates 42 are formed at intervals in the circumferential direction around the axis O.

In this modification, since the resin material is not linearly supplied in the Z direction toward the bottom surface of the molding portion C, the bottom surface of the molding portion C can be reliably suppressed from being locally damaged.

(Second modified example)
FIG. 8 is an enlarged perspective view of the gate bush 110 according to the second modified example of the present embodiment.
In the gate bush 110 shown in FIG. 8, four sub-gates 111 are formed at intervals in the circumferential direction around the axis O. The cross-sectional shape of each sub-gate 111 orthogonal to the flow direction is formed into an oval shape with the circumferential direction around the axis O as the major axis direction. In addition, the sub-gate 111 is formed in a taper shape in which the cross-sectional area of the flow path gradually decreases as it goes downward. In the example of FIG. 8, the sub-gate 111 is reduced in size in both the major axis direction and the minor axis direction as it goes downward. However, the sub-gate 111 may be reduced in size in only one of the major axis direction and the minor axis direction as it goes downward. Further, the flow path cross-sectional area of the sub-gate 111 may be uniform over the entire flow direction.

According to this configuration, the flow rate of the resin material passing through the sub-gate 111 can be increased by forming the sub-gate 111 in an oval shape. Thereby, the resin material can be more efficiently supplied toward the outer peripheral side of the molding portion C.
Further, by forming the sub-gate 111 in a tapered shape, the upper end opening edge 111a of the sub-gate 111 can be formed at a sharper angle than in the case where the sub-gate 111 has a uniform flow passage cross-sectional area. As a result, in the gate cutting step described above, a larger shearing force acts on the connecting portion between the molded product S and the gate portion G. Therefore, the gate cutting process can be performed smoothly, and the remaining gate of the molded product S can be reduced.

(Third modification)
It is an expansion perspective view of gate bush 120 concerning the 3rd modification of this embodiment.
As in the gate bush 120 shown in FIG. 9, only the sub gate 111 may be formed in the nozzle portion 32.

The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment and each modification, a plurality of sub-gates are formed at intervals in the circumferential direction, but the present invention is not limited to this. That is, it suffices if at least one sub-gate is formed.

Further, if the sub-gate extends in a direction intersecting with the Z direction, the inclination angle with respect to the Z direction can be appropriately changed. In this case, the sub gate may extend in the direction orthogonal to the Z direction.
Furthermore, the cross-sectional shape of the sub-gate is not limited to a circular shape or an oval shape, and various shapes such as a polygonal shape can be adopted.
Further, each gate may be arranged at any position in the plane direction orthogonal to the Z direction as long as it is a position facing the bottom surface of the molding portion C in the Z direction.

In the above-described embodiment, the case where the thin plate-shaped molded product S is formed using the mold 1 has been described as an example, but the present invention is not limited to this, and the present invention is applicable to the case where the molded product S having various shapes is formed. The configuration of can be adopted.
Further, in the above-described embodiment, the case where the resin material is used as the molding material has been described, but the present invention is not limited to this, and other materials such as a glass material and a metal material may be used.

In the above-described embodiment, the case where the gate holes and the gates are formed in the gate bush has been described. However, the present invention is not limited to this, and the gate holes and the gates may be directly formed in the first mold. ..
Further, in the above-described embodiment, the case where the molding recess 23 is formed in the second molding die 20 has been described, but if the molding recess is formed in at least one of the first molding die 10 and the second molding die 20, I do not care.

In addition, it is possible to appropriately replace the components in the above-described embodiments with known components without departing from the spirit of the present invention.

1... Mold (molding die)
10... 1st shaping|molding die 11... Mold matching surface 13,100,110,120...Gate bush 20...Second shaping|molding die 41...Main gate (2nd gate opening)
42, 111... Sub gate (first gate opening)

Claims (4)

A first mold having a gate bush for supplying a molding material supplied from a supply source;
A second molding die which is capable of being brought into contact with and separated from the first molding die and which defines a molding portion between the first molding die and the first molding die;
A first gate opening is radially formed on a side surface of the gate bush ,
The first molding die is formed with a second gate opening extending in the moving direction and opening at a portion of the first molding die facing the second molding die in the moving direction. Mold for molding. The first gate opening is opened at a position projecting toward the second molding die side in the movement direction with respect to a mating surface of the first molding die with the second molding die. The molding die according to claim 1. A gate bush is detachably attached to the first mold,
The mold for molding according to claim 1 or 2, wherein the first gate opening is formed in the gate bush. The molding die according to any one of claims 1 to 3, wherein the first gate opening has a flow passage cross-sectional area that gradually decreases toward the downstream side in the flow direction.

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