JP2021094716A - Resin molded product - Google Patents

Abstract

To provide a resin molded product capable of maintaining strength in a weld part.SOLUTION: A nest 24 protrudes into a cavity 20 in a state of a mold clamped. As a result, a part of a molten resin 34 is obstructed in its flow by the nest 24 and flows around an outside of the nest 24. Further, a side surface 60 of the nest 24 has an angle (180-α) with respect to a flow direction of the molten resin 34. Therefore, when the molten resin 34 comes into contact with the side surface 60 of the nest 24, the nest 24 moves toward an arrow E direction, and a flow path of the molten resin 34 in the cavity 20 expands upward. As a result, the molten resin 34 that flows around the nest 24 flows three-dimensionally. As a result, a weld line is formed in a meandering state with respect to the flow direction of the molten resin 34, and at a confluence part 22, an adhesion between the molten resins 34 is increased, and a strength of a weld part can be improved.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to resin molded products.

Patent Document 1 below discloses a technique relating to an injection molding method for a thermoplastic resin. Generally, a weld line is generated in a resin molded product at a confluence portion where molten resins having different flow directions merge in a mold for molding a thermoplastic resin (hereinafter referred to as "resin molded product"). Therefore, in the above-mentioned prior art, an inert fluid is press-fitted into the mold, thereby shifting the position of the confluence portion of the molten resin and suppressing the generation of weld lines.

Japanese Unexamined Patent Publication No. 05-057741

However, in the above-mentioned prior art, since the inert fluid is press-fitted into the mold, when only a part of the molten resin is moved by the inert fluid, in the place where the molten resin is not moved, the resin molded product may be used. The weld line may be formed deeper than the portion of the weld line, and the desired strength may not be obtained in the weld portion including the weld line. That is, there is room for further improvement in maintaining the desired strength in the weld portion.

In consideration of the above facts, an object of the present invention is to provide a resin molded product capable of maintaining strength in a welded portion.

The resin molded product according to the invention according to claim 1 is movable with respect to a fixed-side mold provided with a resin injection port into which molten resin is injected and the fixed-side mold, and the fixed-side mold can be used. On the other hand, it is a resin molded product formed by a mold provided with a movable side mold that forms a cavity portion through which the molten resin flows between the fixed side mold and the fixed side mold in a closed state. It is formed on the upstream side in the flow direction of the molten resin including the confluence portion of the molten resin that has flowed in the cavity portion, and has a plurality of coma portions that are alternately provided so as to sandwich the confluence portion.

In the resin molded product according to the invention of claim 1, a coma portion is formed on the upstream side in the flow direction of the molten resin, including the confluence portion of the molten resin that has flowed in the cavity portion. Further, the coma portions are provided alternately with the confluence portion in between.

Generally, molds for molding resin molded products include a fixed-side mold having a resin injection port into which molten resin is injected by an injection molding machine, and a movable-side mold that can be opened and closed with respect to the fixed-side mold. And are configured to include. Then, in a state where the movable side mold is closed with respect to the fixed side mold, a cavity portion through which the molten resin flows is formed between the movable side mold and the fixed side mold.

For example, in a resin molded product, when two gate ports for injecting molten resin into the main body of the resin molded product are provided, the molten resin injected from one gate port and the molten resin injected from the other gate port Merges between one gate opening and the other gate opening (merging part).

On the other hand, the resin molded product in the present invention is provided with a plurality of frame portions. The frame portion is formed in a resin molded product by a nesting provided separately from the movable side mold and the fixed side mold in the mold.

Further, the coma portion provided in the resin molded product includes a confluence portion of the molten resin (resin molded product) that has flowed in the cavity portion formed in the mold at the time of molding the resin molded product, and is in the flow direction of the molten resin. On the upstream side (one gate opening side, the other gate opening side), they are provided alternately with the confluence portion in between.

That is, in the mold, a plurality of nests are alternately provided on the upstream side in the flow direction of the molten resin, including the confluence portion of the molten resin flowing in the cavity portion, with the confluence portion interposed therebetween. As described above, since the nesting is provided separately from the movable side mold and the fixed side mold, the nesting can be moved independently with the movable side mold closed with respect to the fixed side mold. Can be made to.

For example, at the time of molding a resin molded product, the flow of the molten resin in the cavity is hindered by projecting the nest into the cavity while the movable mold is closed with respect to the fixed mold. The resin pressure due to the molten resin becomes imbalanced. This nesting moves in and out of the cavity during molding of the resin molded product, so that the molten resin can be moved three-dimensionally in the plate thickness direction and the surface direction of the resin molded product.

In this way, by three-dimensionally moving and merging molten resins having different flow directions, the weld line formed at the merging portion in the resin molded product is formed in a meandering state with respect to the flow direction. As a result, in the present invention, as compared with the case where the molten resins having different flow directions are two-dimensionally merged, the adhesion between the molten resins having different flow directions is increased at the confluence portion, and the strength of the weld portion is improved. It becomes possible.

As described above, the present invention has an excellent effect that the strength can be maintained in the weld portion.

It is sectional drawing which shows the state in which the nest protrudes in the mold which molds the resin molded article which concerns on this embodiment. It is an enlarged sectional view of the main part which shows the main part of FIG. 1 in an enlarged manner. It is sectional drawing which shows the state which the nest is pressed in the mold which molds the resin molded article which concerns on this embodiment. FIG. 3 is an enlarged cross-sectional view of a main part shown by enlarging the main part of FIG. It is a top view which shows the cavity surface of the movable side mold side of the mold which molds the resin molded article which concerns on this embodiment. It is a top view corresponding to FIG. 5 which shows the resin molded article which concerns on this embodiment. It is a top view corresponding to FIG. 5 which shows a comparative example.

Hereinafter, the resin molded product according to the embodiment of the present invention will be described with reference to the drawings.
First, the mold structure of the mold for molding the resin molded product according to the embodiment of the present invention will be described.

(Mold structure of mold)
FIG. 1 shows a cross-sectional view of a mold structure 14 of a mold 12 for molding a resin molded product 10 (see FIG. 3) according to an embodiment of the present invention.

As shown in FIG. 1, the mold 12 for molding the resin molded product 10 includes a fixed-side mold 16 and a movable-side mold 18. Although not shown, the fixed-side mold 16 is provided with a resin injection port for injecting molten resin in a cylinder provided in an injection molding machine.

On the other hand, the movable mold 18 can be opened and closed with respect to the fixed mold 16, and the movable mold 18 hits the fixed mold 16 when the movable mold 18 is closed to the fixed mold 16. The movable mold 18 is separated from the fixed mold 16 when it is in contact with the fixed mold 16 and is open to the fixed mold 16.

Here, in a state in which the movable side mold 18 is closed with respect to the fixed side mold 16, that is, in a so-called mold tightening state of the mold 12, the cavity portion 20 is located between the fixed side mold 16 and the movable side mold 18. Is formed.

In this way, the molten resin is injected into the cavity portion 20 formed by the fixed-side mold 16 and the movable-side mold 18, and the molten resin flows in the cavity portion 20. Then, after a predetermined time elapses, the molten resin solidifies in the cavity 20, whereby the resin molded product 10 is molded.

On the other hand, in the state where the movable side mold 18 is opened with respect to the fixed side mold 16, that is, in the so-called mold open state of the mold 12, resin molding formed in the cavity portion 20 by the mold tightened mold 12. The product 10 is separated from the mold 12 so that it can be taken out.

Generally, as shown in FIG. 7, when the resin molded product 200 is provided with two gate ports 202 and 204 for injecting the molten resin into the cavity portion 201 for molding the resin molded product 200, one of the gate ports is provided. The resin portion 206 in which the molten resin injected from 202 and flowing in the direction of arrow A is solidified and the resin portion 208 in which the molten resin injected from the other gate port 204 and flowing in the direction of arrow B are solidified merge. Join at part 210. At the merging portion 210, the molten resins having different flow directions merge with each other and the flow of the molten resin is stopped, so that the weld line WL'is formed in the resin molded product 200.

On the other hand, in the present embodiment, as shown in FIG. 5, on the movable side mold 18 side of the mold 12, the confluence portion 22 capable of generating a weld line in the resin molded product 10 (see FIG. 6) is provided. A plurality of nests 24, 26, 28, 30, 32 are provided so as to sandwich the merging portion 22.

Note that FIG. 5 is a plan view showing the cavity surface 18A on the movable side mold 18 side of the mold 12, and FIG. 5 shows the molten resins 34 and 36 flowing in the cavity portion 20. Here, in the cavity portion 20 shown in FIG. 5, the vertical lines shown along the vertical direction in the figure indicate the velocity distributions of the molten resins 34 and 36, and flow in the cavity portion 20 at substantially the same flow velocity. If this is the case, the vertical line spacing will be approximately the same in the horizontal direction in the figure.

Here, nesting 24, 26, 28, 30, 32 will be specifically described. As shown in FIG. 5, the nests 24, 26, and 28 are provided on the upstream side of the merging portion 22 with respect to the flow direction (arrow C direction) on the molten resin 34 side, and the nests 30, 32 are the molten resin 36. It is provided on the upstream side of the merging portion 22 with respect to the flow direction (arrow D direction) on the side.

Further, the nests 24, 26 and the nest 30, and the nests 26, 28 and 32 are not arranged on the same axis, respectively, and the nest 30 is viewed along the flow direction on the molten resin 34 side. Part of the nests 24 and 26 are arranged so as to overlap each other. Further, the nesting 32 is arranged so that a part of the nesting 26 and 28 overlaps when viewed along the flow direction on the molten resin 34 side. That is, the nests 24, 26, 28 and the nests 30, 32 are arranged alternately with the merging portion 22 in the plan view.

Note that these nests 24, 26, 28, 30, and 32 have substantially the same configuration. Therefore, the nesting 24 will be described on behalf of these.

As shown in FIG. 1, for example, the cavity surface 18A side of the movable mold 18 has a predetermined angle (for example, 45 °) with respect to the flow direction (arrow C direction) of the molten resin 34. The accommodating portion 38 is recessed along substantially the vertical direction (the plate thickness direction of the movable mold 18 (arrow t'direction)) in a state of being inclined with (α), and is inside the accommodating portion 38. The nest 24 is accommodated in the.

A through hole 42 communicating with the mounting portion 40 provided at the back of the accommodating portion 38 is provided in the central portion of the back wall 38A of the accommodating portion 38, and the rod 44 is inserted into the through hole 42. .. On the other hand, the mounting portion 40 is provided with a cylinder 46, and the cylinder 46 is fixed to the mounting seat 50 via a plurality of brackets 48.

One end of the rod 44 in the longitudinal direction is housed in the cylinder 46, and a spring (not shown) housed in the cylinder 46 allows the rod 44 to move in and out of the cylinder 46 along the axial direction of the rod 44. It is said that. The rod 44 is in a state of protruding in a natural state of the spring.

Further, a piston 52 is provided at the other end of the rod 44 in the longitudinal direction in accordance with the shape of the nest 24. The nesting 24 is fixed to the tip surface 52A of the piston 52, and the nesting 24 can move in the accommodating portion 38 along the axial direction of the rod 44. That is, the nest 24 moves in the accommodating portion 38 in a substantially vertical direction in a state of being inclined with respect to the flow direction of the molten resin 34.

FIG. 2 shows an enlarged cross-sectional view of a main part obtained by enlarging the main part of FIG. As shown in FIGS. 1 and 2, in the nesting 24, the tip portion 54 of the nesting 24 projects toward the inside of the cavity portion 20 of the movable mold 18. The vector shown in the cavity portion 20 shown in FIG. 2 shows the velocity distribution of the molten resins 34 and 36, and in the plate thickness direction (arrow t'direction) of the movable mold 18, the molten resins 34 and 36 The number of vectors increases according to the speed. The same applies to FIG. 4, which will be described later.

On the other hand, FIG. 3 shows a cross-sectional view of the mold structure 14 of the mold 12 corresponding to FIG. 1, and FIG. 4 shows an enlarged cross-sectional view of a main part obtained by enlarging the main part of FIG. There is. In FIG. 4, in the molten resins 34 and 36, the portion where the resin pressure is high is shown darkly, and the portion where the resin pressure is low is shown lightly.

As shown in FIGS. 3 and 4, in a state where the nesting 24 is pressed and the movement of the nesting 24 is restricted, the tip surface 54A of the nesting 24 constitutes a part of the cavity surface 18A of the movable mold 18. Is set to.

That is, when the nest 24 is pressed and the movement of the nest 24 is restricted, the tip surface 54A of the nest 24 and the cavity surface 18A of the movable mold 18 are substantially flush with each other. When turned over, it is preset so that the movement of the nest 24 is restricted at a position where the tip surface 54A of the nest 24 and the cavity surface 18A of the movable mold 18 are substantially flush with each other.

As shown in FIG. 5, for example, the nest 24 has a rectangular parallelepiped shape that is rectangular in a plan view, and is a pair of side surfaces on the long side arranged along the flow direction of the molten resin 34. 56, 58 and a pair of side surfaces 60, 62 on the short side arranged along a direction substantially orthogonal to the flow direction (arrow C direction) of the molten resin 34 are included. The side surface 60 is arranged on the upstream side of the side surface 62 along the flow direction of the molten resin 34.

Further, as described above, as shown in FIGS. 1 and 3, the nesting 24 is inclined along the flow direction (arrow C direction) of the molten resin 34 along the substantially vertical direction in the accommodating portion 38. The tip surface 54A of the nesting 24 is set to be substantially flush with the cavity surface 18A of the movable mold 18. Therefore, the tip surface 54A of the nest 24 has a shape cut off along the flow direction of the molten resin.

By the way, as described above, the accommodating portion 38 has a predetermined angle (α) that is an acute angle with respect to the flow direction (arrow C direction) of the molten resin 34, and is recessed along substantially the vertical direction in an inclined state. The nesting 24 is housed in the housing part 38.

Therefore, as shown in FIGS. 3 and 4, when the tip surface 54A of the nesting 24 is substantially flush with the cavity surface 18A of the movable side mold 18, the side surface 60 of the nesting 24 and the movable side mold 18 The angle formed with the cavity surface 18A is α, and the side surface 60 of the nest 24 has an angle (α) with respect to the flow direction of the molten resin 34.

On the other hand, as shown in FIGS. 1 and 2, when the tip portion 54 of the nesting 24 protrudes into the cavity portion 20, the side surface 60 of the nesting 24 is at an angle (180-) with respect to the flow direction of the molten resin 34. Will have α).

(Action and effect of resin molded products)
Next, the action and effect of the resin molded product according to the embodiment of the present invention will be described.

In addition, here, the effect of the resin molded product will be described including the action at the time of molding the resin molded product to be molded using the above-mentioned mold.

As shown in FIGS. 1 and 5, when the molten resin is injected into the cavity 20 while the mold 12 is molded, the molten resin 34 injected from one gate port and the other gate port are injected. The molten resin 36 injected from the above flows in the cavity portion 20.

As described above, in the state where the mold 12 is molded, the nests 24, 26, 28, 30, and 32 project toward the inside of the cavity portion 20.

Therefore, the flow of a part of the molten resin 34 is hindered by the nests 24, 26, 28, and wraps around the outside of the nests 24, 26, 28 along the flow direction (arrow C direction) of the molten resin 34. It flows in this way. Further, a part of the molten resin 36 is hindered by the nests 30 and 32, and flows around the outside of the nests 30 and 32 along the flow direction (arrow D direction) of the molten resin 36. ..

Here, as shown in FIG. 2, for example, in a state where the nesting 24 protrudes into the cavity portion 20, the side surface 60 of the nesting 24 has an angle (180-α) with respect to the flow direction of the molten resin 34. .. Therefore, when the molten resin 34 comes into contact with the side surface 60 of the nest 24, the side surface 60 of the nest 24 is pressed by the resin pressure of the molten resin 34.

When the side surface 60 of the nesting 24 is pressed (pressing pressure F1) in this way, the pressing force F1 presses the nesting 24 in the accommodating portion 38 through the side surface 60 of the nesting 24. It is converted into a pressing pressure (F2).

That is, as shown in FIGS. 1 and 2, when the molten resin 34 comes into contact with the side surface 60 of the nest 24, the nest 24 is a spring (not shown) housed in the cylinder 46 due to the resin pressure of the molten resin 34. It is urged along the direction (arrow E direction) against the urging force.

As a result, as shown in FIGS. 3 and 4, the nesting 24 moves upward (in the direction of arrow E), and the flow path (volume of the cavity portion 20) of the molten resin 34 in the cavity portion 20 becomes larger. It will spread to the upper side (cavity surface 18A side).

Further, as described above, the nesting 24 moves in the accommodating portion 38 substantially in the vertical direction in a state of being inclined with respect to the flow direction (arrow C direction) of the molten resin 34. Therefore, as shown in FIGS. 2 and 4, when the intersection P of the tip surface 54A of the nesting 24 and the side surface 60 of the nesting 24 is viewed, the intersection 24 moves upward. Therefore, it moves upward in the flow path (cavity portion 20) and moves upstream in the flow direction (arrow C direction) of the molten resin 34.

Further, as described above, the molten resin 34 whose flow is obstructed by the nest 24 flows around the outside of the nest 24 along the flow direction (arrow C direction) of the molten resin 34.

That is, in the present embodiment, the molten resin 34 flowing around the nest 24 is three-dimensionally formed in the plate thickness direction (arrow t direction shown in FIG. 4) and the surface direction (plane direction shown in FIG. 6) of the resin molded product 10. It will flow, and the resin pressure due to the molten resin 34 will be imbalanced depending on the presence or absence of the nest 24 in the cavity portion 20. Then, the same phenomenon occurs around the nests 26 and 28 other than the nest 24 shown in FIG. 5 as well as around the nest 24.

That is, the molten resin 34 that flows around the nests 24, 26, and 28 flows three-dimensionally in the plate thickness direction and the plane direction of the resin molded product 10 (see FIG. 6). As a result, the molten resin 34 flows three-dimensionally on the downstream side in the flow direction including around the nests 24, 26, and 28.

The molten resin 36 that flows around the nests 30 and 32 is the same as the molten resin 34, and the molten resin 36 includes the circumferences of the nests 30 and 32 and is the thickness of the resin molded product 10 on the downstream side in the flow direction. It will flow three-dimensionally in the direction and the plane direction.

In this way, as shown in FIGS. 4 and 5, the weld line WL (weld line WL) is formed by three-dimensionally merging the molten resins 34 and 36 having different flow directions in the plate thickness direction and the surface direction of the resin molded product 10. (See FIG. 6) is formed in a state of meandering with respect to the flow direction.

That is, as compared with the case where the molten resins having different flow directions are two-dimensionally merged as shown in FIG. 7, in the present embodiment, as shown in FIGS. 5 and 6, the weld is welded at the joining portion 22. The structure of the portion 63 is complicated, the adhesion between the molten resins 34 and 36 is increased, and the strength of the weld portion 63 can be improved. This makes it possible to maintain the strength of the weld portion 63 even if, for example, a high-rigidity resin having low fluidity or a reinforced resin kneaded with carbon fibers is used.

On the other hand, as shown in FIG. 4, in the present embodiment, when the nesting 24 moves upward and the movement of the nesting 24 is restricted, the tip surface 54A of the nesting 24 becomes the cavity of the movable mold 18. It is almost flush with the surface 18A. As a result, the molten resin 34 is solidified along the tip surface 54A of the nest 24. Therefore, in the present embodiment, as shown in FIG. 6, the resin molded product 10 has the frame portions 64, 66, 68, 70, 72 as the nests 24, 26, 28, 30, 32 shown in FIG. Traces will remain on each.

As described above, in the present embodiment, the molten resin 34 is solidified in a state where the tip surface 54A of the nesting 24 is substantially flush with the cavity surface 18A of the movable mold 18, so that the plate thickness of the resin molded product 10 is increased. There is no thinned part, and the decrease in mechanical strength can be suppressed.

Further, for example, as a comparative example, when the tip surface 54A of the nest 24 is set to be deeper than the cavity surface 18A of the movable mold 18, and although not shown, the top portion is projected in the resin molded product. In this embodiment, it is possible to suppress an increase in the weight of the resin molded product 10.

By the way, in the present embodiment, as shown in FIGS. 1 and 3, a predetermined angle is sharp with respect to the flow direction (arrow C direction) of the molten resin 34 on the cavity surface 18A side of the movable mold 18. In a state of being inclined with an angle (α), the accommodating portion 38 is recessed substantially in the vertical direction, and the nesting portion 24 is accommodated in the accommodating portion 38. It is said that it can move in the vertical direction.

Therefore, in the present embodiment, as shown in FIGS. 1 and 2, for example, when the molten resin 34 comes into contact with the side surface 60 of the nest 24, the side surface 60 of the nest 24 is pressed by the resin pressure of the molten resin 34. (Pressure F1) is applied, and the pressing force F1 is converted into a pressing force (F2) that presses the nesting 24 in the direction of accommodating the nesting unit 38 through the side surface 60 of the nesting 24. As a result, the nesting 24 is urged along a direction (arrow E direction) that opposes the urging force of a spring (not shown) housed in the cylinder 46.

As described above, in the present embodiment, the nesting 24 can be moved along the vertical direction by the resin pressure (resin pressure) of the molten resin 34 and the urging force of the spring. Therefore, in the present embodiment, the cost can be reduced as compared with the case where the nest 24 is moved by an electronically controlled hydraulic mechanism or the like.

Further, in the present embodiment, as described above, the nest 24 is moved by the resin pressure of the molten resin 34. As a result, the nesting 24 can be driven in accordance with the passing timing of the molten resin 34 flowing in the cavity portion 20, and the weld portion 63 can be stably reinforced.

On the other hand, a slight gap is provided between the nest 24 and the accommodating portion 38 in order to move the nest 24. When the resin molded product 10 is molded, for example, when the injection pressure is high and the molten resin 34 flows between the nesting 24 and the accommodating portion 38, burrs are generated in the resin molded product 10. There is. In this case, it becomes necessary to remove burrs by secondary processing after molding, which leads to an increase in cost. That is, the mass productivity is not good.

On the other hand, in the present embodiment, as shown in FIG. 4, the accommodating portion 38 and the nesting 24 are inclined with an acute angle (α) with respect to the flow direction of the molten resin 34. It is provided. That is, the accommodating portion 38 and the nesting 24 have components that go in the direction opposite to the flow direction (arrow C direction) of the molten resin 34.

Therefore, for example, although not shown, in the present embodiment, the generation of burrs is suppressed as compared with the case where the accommodating portion 38 and the nesting 24 are provided along the direction orthogonal to the flow direction of the molten resin 34. It becomes possible to improve mass productivity.

In the present embodiment, the nesting 24 is set to be provided on the movable side mold 18 side, but the nesting 24 may be provided on the fixed side mold 16 side, and the movable side mold may be provided. It may be provided on the mold 18 side and the fixed side mold 16.

Further, in the present embodiment, as shown in FIG. 5, the nests 24, 26 and the nest 30 and the nests 26, 28 and the nest 32 are not arranged on the same axis, respectively, and the nest 30 is the molten resin 34. When viewed along the flow direction on the side, parts of the nests 24 and 26 are arranged so as to overlap, and the nest 32 is a part of the nests 26 and 28 when viewed along the flow direction on the molten resin 34 side. Are arranged so that they overlap.

However, the present invention is not limited to this because it is sufficient that the molten resins 34 and 36 having different flow directions can be three-dimensionally merged in the plate thickness direction and the surface direction of the resin molded product 10. For example, the nests 24, 26, 28 and the nests 30, 32 may be randomly arranged on the upstream side of the molten resin 34, 36 in the flow direction with the merging portion 22 interposed therebetween.

Although an example of the embodiment of the present invention has been described above, the present invention can be implemented with various modifications without departing from the gist thereof. Further, it goes without saying that the scope of rights of the present invention is not limited to the above-described embodiment.

10 Resin molded product 12 Mold 16 Fixed side mold 18 Movable side mold 20 Cavity part 22 Confluence part 34 Molten resin 36 Molten resin 64 Top part 66 Top part 68 Top part 70 Top part 72 Top part

Claims (1)

A fixed-side mold having a resin injection port into which molten resin is injected, and the fixed-side mold that can be opened and closed with respect to the fixed-side mold and closed to the fixed-side mold. It is a resin molded product that is molded by a mold provided with a movable side mold that forms a cavity in which the molten resin flows between the two.
A resin molded product having a plurality of coma portions alternately provided on the upstream side in the flow direction of the molten resin, including the confluence portion of the molten resin that has flowed in the cavity portion.

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