JP4702138B2 - Manufacturing method of box-shaped resin molded product - Google Patents

Description

  The present invention relates to a method for manufacturing a box-shaped resin molded product having a box.

  For example, when an article having a box shape such as a console box is molded by an injection molding method, air (air) or a gas generated from a raw material may remain in a cavity into which resin flows. If these air and gas remain, the resin cannot be completely filled, resulting in short shots (poor filling), or the air or gas is compressed and the molding becomes hot, causing burned or burned parts. There is a case.

Thus, for example, in the invention described in Patent Document 1, air and gas remaining in the cavity are discharged out of the mold by providing a gas vent hole in the cavity.
JP 2005-53127 A

  By the way, the position where air or gas remains as described above is a position (final filling position) where the resin is finally filled in the cavity. However, in the case of a box-shaped resin molded product, the resin flows into the cavity from multiple directions, and the inflow mode changes depending on the molding conditions, so it is difficult to accurately predict the final filling position. It is. Therefore, the formed vent hole may be displaced from the final filling position, which causes a molding defect. In addition, it is not desirable to form the gas vent holes over a wide range in order to cover the deviation of the prediction of the final filling position, which increases the cost of the mold.

  The present invention has been made in view of the above problems, and provides a method for producing a box-shaped resin molded product that can eliminate molding defects caused by gas generated when a box-shaped resin molded product having a box is manufactured. It aims to be realized.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a box-shaped resin having a box body in which a molten resin is filled in a cavity formed in a mold formed by combining a plurality of molds. In the method of manufacturing a molded product, the box is formed to have a bottom, a side wall standing on the periphery of the bottom, and an opening that opens at the upper end of the side wall. A gate serving as an inlet for filling into the cavity is provided at a position other than the final filling position where the resin finally flows into the cavity, and the mold portion corresponding to the bottom has the gate. A gas venting mechanism for releasing the gas in the cavity to the outside of the cavity is provided, and the plurality of molds are combined so that the thickness in the cavity corresponding to the side wall is from the part corresponding to the upper end of the side wall to the lower end. Corresponding Position to form the cavity so as to gradually become thinner as going, and summarized in that filling the resin to the cavity.

  The resin has the property of being easy to flow because the space in the cavity to be filled is wider, that is, the thicker the cavity, the less the flow resistance. According to this configuration, the flow of the resin is fast in the cavity corresponding to the upper end of the side wall having a large space, while the cavity becomes thinner toward the lower end of the side wall, so that the resin does not flow easily and the resin flows. Will be late. That is, the cavity corresponding to the bottom is the final filling position where the resin is finally filled. Therefore, since the degassing mechanism is provided in the mold corresponding to the bottom portion, the gas remaining at the final filling position (bottom portion) can be discharged from the degassing mechanism, and a box-shaped resin molded product having a box is obtained. Molding defects due to gas or the like generated during production can be eliminated.

  The invention according to claim 2 is the method for manufacturing a box-shaped resin molded article according to claim 1, wherein the position at which the gas venting mechanism is provided is a part of the portion of the mold corresponding to the bottom, The gist is to delay the inflow speed of the resin into the space in the cavity corresponding to the part of the mold provided with the gas venting mechanism depending on the structure or state of the mold.

  According to this configuration, the cost of the mold can be reduced by providing the gas venting mechanism only in a part of the mold corresponding to the bottom. In addition, since the flow of resin is delayed in the space in the cavity corresponding to the bottom of the molded product, that is, the bottom of the molded product, depending on the structure or state of the mold, this space is finally filled. Position. Therefore, even if the location where the gas venting mechanism is provided is limited, the gas can be released from the gas venting mechanism, and molding defects due to gas or the like generated when manufacturing a box-shaped resin molded product having a single box body are eliminated. be able to.

  According to a third aspect of the present invention, in the method for manufacturing a box-shaped resin molded product according to the second aspect, the part corresponding to the part of the mold in which the gas venting mechanism is provided by a part of the mold The cavity corresponding to the part of the mold provided with the degassing mechanism is formed by making the thickness in the cavity thinner than the thickness in the other cavity corresponding to the bottom. The gist is to delay the flow rate of resin into the interior space.

  According to this configuration, since the thinly formed space in the cavity is narrower than the surrounding space, the resin flows in slowly, so the gas can be vented with a simple configuration that changes the thickness of the mold. The inflow of the resin into the cavity formed by a part of the mold provided with the mechanism can be delayed.

  The method for producing a box-shaped resin molded product of the present invention can eliminate molding defects caused by gas or the like generated when a box-shaped resin molded product having a box is produced.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which the present invention is embodied in a method for manufacturing a console box as a box-shaped resin molded product disposed in an automobile will be described with reference to FIGS. In the following description, “front” refers to the forward direction of the vehicle, and “rear” refers to the backward direction of the vehicle. In addition, the “left”, “right”, “up”, and “down” directions are the same as the “left”, “right”, “up”, and “down” directions with respect to the front of the vehicle. FIG. 1 is a perspective view showing a situation inside a vehicle compartment provided with a console box 1. FIG. 2 shows the main body 1a of the console box 1 immediately after being manufactured by the manufacturing method of the present embodiment. The console box 1 is further assembled to the main body 1a by attaching a predetermined member to FIG. The finished product as shown is placed in the passenger compartment.

  As shown in FIG. 1, the console box 1 formed of a thermoplastic resin (polypropylene (PP) in the present embodiment) has a front portion below the instrument panel 3 at the center of the vehicle 2 in the vehicle width direction. It is arranged to enter. The console box 1 includes a storage portion 6 as a box having a box shape on the vehicle rear side, and a right side portion 7a extends from the right side wall 6a in the vehicle width direction of the storage portion 6 toward the front of the vehicle. In addition, a left side portion 7b extends from the left side wall 6b toward the front of the vehicle. As shown in FIGS. 1 and 2, the storage section 6 includes a rear side wall 6 c that forms a rear side wall and a front side wall 6 d that forms a front side wall. The storage unit 6 is formed with an opening 6e that is surrounded by the side walls 6a to 6d and opens at the upper ends of the side walls 6a to 6d and can store objects to be stored. A bottom portion 6f is provided below 6e in the vertical direction.

Next, the structure of the right side wall 6a and the left side wall 6b of the storage part 6 will be described with reference to FIG. 4 is a cross-sectional view taken along line AA shown in FIG.
As shown in FIG. 4, the right side wall 6a and the left side wall 6b of the storage unit 6 are formed so that the thickness in the left-right direction gradually decreases from the upper end to the lower end (bottom 6f) of each side wall 6a, 6b. Yes. That is, the side walls 6a and 6b are formed such that the upper end is thicker than the lower end. In the present embodiment, the thickness in the left-right direction of the upper ends of the side walls 6a, 6b is formed to about 3.5 to 5.0 mm, and the thickness in the left-right direction of the lower ends of the side walls 6a, 6b is about 2.0. It is molded to ˜3.0 mm. Further, although not shown in the drawing, the rear side wall 6c and the front side wall 6d are similarly formed with a thicker upper end than the bottom 6f.

  Next, the structure of the back surface of the accommodating part 6 is demonstrated based on FIG. FIG. 3 shows a case where the storage unit 6 is viewed from the back side, and the upper side in the figure coincides with the left side when the console box 1 is arranged in the vehicle 2, and the lower side in the figure is arranged in the vehicle 2 Matches the right side of

  As shown in FIGS. 3A and 3B, a thin bottom portion 6g that is recessed upward in the vertical direction as compared with other portions of the bottom portion 6f is formed at the rear end portion of the left edge of the bottom portion 6f. That is, the thickness of the thin bottom portion 6g is thinner than the thickness of other portions of the bottom portion 6f. Note that the thickness of the bottom portion 6f in the vertical direction is formed to 2.0 mm, whereas the thickness of the thin bottom portion 6g in the vertical direction is formed to 1.0 mm.

  As shown in FIG. 1, in the completed state of being arranged in the passenger compartment, the storage portion 6 is provided with a lid portion 7 that can be opened and closed so as to cover the opening 6e, and the right side portion 7a and the left side. A shift lever 4 is provided between the side portions 7b. Further, a cover plate 5 is provided above the right side portion 7a and the left side portion 7b with the shift lever 4 protruding so that the inner surfaces of the right side portion 7a and the left side portion 7b cannot be seen. Yes.

Next, the state of the main body 1a of the console box immediately after being manufactured by the manufacturing method of the present embodiment will be described in detail with reference to FIG.
The main body 1a in the present embodiment is manufactured by injection molding using a side gate method. When molded by the side gate method, the molten resin injected from the nozzle of the injection molding machine flows into the cavity in the mold through the spool, runner, and gate. The part which the resin which flowed in to hardened remains. Accordingly, when these portions are removed from the console box 1 as a finished product, gate traces remain, so that the gate traces are designed to appear inconspicuous places in the finished product. In the present embodiment, as shown in FIG. 2, the portion indicated by 8 is a cured portion where the resin is cured in the runner, and the portions indicated by 9a and 9b are the cured portions where the resin is cured at the gate. That is, since the gate mark is provided on the inner surfaces of the right side portion 7a and the left side portion 7b and at the upper end, it cannot be seen in the state of being arranged in the vehicle compartment as shown in FIG.

  Next, the structure of the metal mold | die and cavity used for manufacturing the main-body part 1a of this embodiment is demonstrated. In the present embodiment, a mold is formed by combining a plurality of molds, and a cavity having a shape corresponding to a molded product to be manufactured is formed in the mold.

  The cavity is formed such that the thickness in the cavity gradually decreases from the portion corresponding to the upper end of the right side wall 6a and the left side wall 6b to the portion corresponding to the lower end. Further, the cavity is formed such that the portion of the bottom portion 6f corresponding to the thin bottom portion 6g is thinner than the portion corresponding to the other portion of the bottom portion 6f.

  A degassing mechanism is provided at a portion of the mold corresponding to the portion indicated by 10 of the thin bottom portion 6g in FIG. In the present embodiment, the gas venting mechanism is realized by forming a corresponding part of the mold with a porous material having fine holes. In addition, the position where the gas venting mechanism is provided when the portion of the cavity 6 corresponding to the side walls 6a, 6b is formed as described above and the inflow mode of the resin in the cavity is predicted by computer simulation, Finally, it is set at a portion (final filling position) where the resin is predicted to flow in. Further, the cavity part corresponding to the thin bottom part 6g is within a square range of 30 mm × 30 mm around the part corresponding to the part of the mold provided with the gas venting mechanism, and this numerical value is a computer. This value includes a prediction error when the inflow mode of the resin is predicted by simulation.

  Further, a gate (not shown) serving as an inlet for filling the resin toward the cavity portion corresponding to the front of the main body portion 1a is formed at a portion corresponding to the hardening portion 9a shown in FIG. . Further, a gate 19b (shown in FIG. 5 (a)) serving as an inlet for filling the resin toward the cavity portion corresponding to the storage portion 6 is formed in a portion corresponding to the cured portion 9b in the mold. Yes.

  Next, a manufacturing process for forming the main body 1a will be described with reference to FIGS. 5 and 6, the console box indicated by a two-dot chain line indicates the cavity 11 in the mold, and the colored portion indicates the resin 12 that has flowed into the cavity 11. . Accordingly, in FIGS. 5 and 6, the reference numerals of the members constituting the cavity 11 are indicated by the numbers added to the corresponding reference numerals of the console box 1 used in FIGS. 1 to 4. . Further, as molding conditions for injection molding, the resin temperature is set to 210 ° C., the mold temperature is set to 30 ° C., and the resin filling time is set to 5 Sec.

  First, the cavity 11 is formed by combining a plurality of molds. At this time, the cavity 11 has a shape corresponding to the storage unit 6 as described above. Subsequently, an injection molding machine (not shown) injects the melted resin 12 from each gate into the cavity 11 while applying pressure.

  As shown in FIG. 5A, the resin 12 flowing from the gate 19b flows from the right side portion 17a in the cavity 11 to the right side wall 16a of the storage portion 16, and travels through the front side wall 16d. It also flows into the left side wall 16b. At this time, the right side wall 16a and the left side wall 16b of the cavity 11 become narrower in the space in the cavity 11 from the upper end to the lower end in the figure, so that the resin inflow rate of the resin 12 at the upper end becomes the fastest. The inflow speed of the resin 12 becomes slower toward the lower end. As a result, the resin 12 flows into the upper side of the right side wall 16a and the left side wall 16b to the rear side in FIG.

  When the inflow of the resin 12 further proceeds, as shown in FIG. 5 (b), the resin 12 flowing in from the right side wall 16a in the cavity 11 reaches the rear side wall 16c and flows in from the left side wall 16b. 12 further flows toward the rear of the left side wall 16b. At this time, due to the difference in the inflow velocity of the resin 12 between the upper end and the lower end of the left side wall 16b in the figure, the upper side and the bottom 16f side of the left side wall 16b in the figure are further increased than those shown in FIG. There is a difference in the inflow amount of the resin 12.

  Then, as shown in FIG. 5C, the resin 12 flowing in from the right side wall 16a in the cavity 11 and the resin 12 flowing in from the left side wall 16b merge at the rear side wall 16c. Normally, when two resin flows merge, a linear weld line is generated on the front and back portions of the merged portion. Weld lines are not preferable because they lead to a decrease in strength at the location of occurrence and deterioration in appearance, but the occurrence of weld lines depends on the angle at which the two flows merge (association angle), and the angle of association is large (120 degrees). If it is ˜150 ° or more, preferably 130 ° or more, the occurrence of weld lines can be suppressed. In the present embodiment, since the resin 12 flows in the right side wall 16a and the left side wall 16b in the cavity 11 at the upper end in the drawing earlier than the lower end, the flows of the two resins 12 are not shown when they join each other. As shown in FIG. 5 (c), the interval increases from the top to the bottom, and the meeting angle also increases. Therefore, in this embodiment, the generation of weld lines when the resin 12 joins is suppressed.

The resin 12 that has flowed in this way finally flows into the bottom 16 f in the cavity 11. The state at that time will be described with reference to FIG.
As shown in FIG. 6 (a), the resin 12 flows into the bottom 16f in the cavity 11 from the right side shown in FIG. 6 (a), that is, from the right side wall 16a side first. The resin 12 flows from the left side shown in (a), that is, from the left side wall 16b.

  When the inflow of the resin 12 further proceeds, as shown in FIG. 6B, the resin 12 flows into a wide range of the bottom portion 16f in the cavity 11. At this time, the resin 12 flows around the thin bottom portion 16g in the cavity 11, but since the space of the thin bottom portion 16g is narrower than the surrounding space, the resin 12 to the thin bottom portion 16g. Inflow is delayed.

  Then, as shown in FIG. 6C, the resin 12 finally flows into the thin bottom portion 16 g in the cavity 11, and the thin bottom portion 16 g becomes the final filling position of the resin 12. Further, since a degassing mechanism is provided at the portion of the mold corresponding to the thin bottom portion 16g, the gas remaining in the cavity 11 is released from the degassing mechanism to the outside of the cavity 11, and the gas etc. Generation | occurrence | production of the molding defect resulting from can be suppressed.

When the filling of the resin 12 is completed, the resin body 12 is removed from the mold in the state of the main body 1a shown in FIG.
The effect which the manufacturing method of this embodiment demonstrated above show | plays is shown below.

  (1) The main body 1a is formed with a plurality of molds, and the cavity 11 is formed so that the thickness of the side walls 16a and 16b in the cavity 11 gradually decreases from the upper end to the lower end of the side walls 16a and 16b. The cavity 11 thus formed is filled with a resin 12. The resin has a property that the space in the cavity 11 to be filled is wider, that is, the thicker the cavity 11 is, the easier the flow is because the flow resistance decreases. Accordingly, the resin 12 flows from the upper end having a wide space in the cavity 11, and the inflow of the resin 12 to the lower end is delayed. As a result, it becomes easy to mold so that the final filling position of the resin 12 comes to the bottom portion 16f corresponding to the portion of the mold provided with the gas venting mechanism, and the gas in the cavity can be suitably discharged. It is possible to eliminate molding defects caused by gas or the like generated when the main body 1a having a box is manufactured.

  (2) Since the upper ends of the side walls 16a to 16d in the cavity 11 are formed to be thicker than the lower ends, the resin 12 flowing from the right side wall 16a and the resin flowing from the left side wall 16b in the cavity 11 are formed. The meeting angle at the time of joining 12 becomes large. Therefore, generation of a weld line can be suppressed, and the appearance and strength of the console box 1 can be improved.

  (3) The position where the gas venting mechanism is provided is a part of the mold portion corresponding to the bottom portion 6f, and a thin space that is a space in the cavity 11 corresponding to the die portion provided with the gas venting mechanism. The flow rate of the resin into the bottom 16g was delayed. Therefore, by providing the gas venting mechanism only in a part of the mold corresponding to the bottom 6f, the cost of the mold can be reduced. In addition, the thin bottom portion 16g in the cavity 11 formed by a part of the mold provided with the gas venting mechanism has the slowest inflow of the resin even at the bottom portion 16f where the inflow of the resin is slow. Become. Therefore, even if the location where the gas venting mechanism is provided is limited, the gas can be released from the gas venting mechanism, and molding defects due to the gas generated when the main body portion 1a having the box body is manufactured can be further eliminated. .

  (4) The cavity is formed so that the thickness of the thin bottom portion 16g in the cavity 11 is thinner than the thickness of the bottom portion 16f in the cavity 11. Accordingly, the space of the thin bottom portion 16g in the cavity 11 is narrower than the surrounding space, so that the resin 12 flows slowly and the thickness of the mold is changed as shown in (3). The effect which was able to be produced can be produced.

  (5) The thin bottom portion 16g in the cavity 11 is formed such that the back surface of the bottom portion 16f is recessed to reduce the thickness. When the console box 1 is disposed on the vehicle 2, the back surface of the bottom portion 6 f is not visible, so that the effect (4) can be achieved without impairing the design of the console box 1.

  (6) The main body 1a is formed by a side gate method. Therefore, as in the case of molding by the tunnel gate method, when the molded product is taken out of the mold, it is possible to suppress the problem that the resin residue generated by cutting the solidified resin at the gate is attached to the molded product. . As a result, the design of the main body 1a can be improved.

The configuration of the present embodiment may be changed as follows.
-Although the case where the main-body part 1a of the console box 1 was manufactured was shown in this embodiment, what is manufactured is not limited to the console box 1, What is necessary is just a molded article which has another box shape.

-How to attach a gate is not limited to what was shown in this embodiment, For example, you may change the position of the gate for accommodating parts, such as providing in the left side part 7b.
In addition, the gate may be provided at the lower end of the front side wall 6d if there is no problem in design, and the gate position may be set so that the resin flows from the side of the box. More specifically, the gate may be provided at a portion of a mold facing the space 7c surrounded by the side portions 7a and 7b and the front side wall 6d, which is substantially the center of the main body portion 1a of the console box 1.

-The thickness of the molded product and the cavity shown in the present embodiment may be appropriately changed according to the structure of the article to be molded.
-Although the structure which uses a porous material as a degassing mechanism was shown, you may change to the structure of providing an air vent hole etc., for example.

  In order to delay the inflow of the resin 12 to the part where the gas venting mechanism is provided, the configuration may be changed such that a weir or the like for restricting the inflow of the resin 12 is provided. Further, the temperature of the part of the mold provided with the gas venting mechanism may be set lower than the temperature of the part of the other mold so that the flow of the resin 12 is delayed.

  -Although the console box 1 of this embodiment was shape | molded with polypropylene (PP), this may be another resin member, for example, polyethylene (PE), polystyrene (PS), polyamide (PA), polyacetal (POM) etc. It may be changed.

Next, the technical idea that can be understood from the above-described embodiment and modification examples will be described below.
(A) In a console box manufacturing method in which a resin formed in a mold formed by combining a plurality of molds is filled with a dissolved resin, the console box has a bottom portion and a peripheral edge of the bottom portion. It is formed to have a side wall that is erected, an opening that opens at the upper end of the side wall, and a side part that extends from the side wall and serves as a side part of the console box. A gate serving as an inlet for filling the tee is provided at least on the side portion, and a degassing mechanism for releasing the gas in the cavity to the outside of the cavity is provided at the portion of the mold corresponding to the bottom portion. And the thickness of the cavity corresponding to the side wall is changed from a portion corresponding to the upper end of the side wall to a portion corresponding to the lower end. Gradually the form a cavity so that thinner, a method of manufacturing a console box, which comprises filling the resin to the cavity Te.
(B) The position where the gas venting mechanism is provided is a part of the mold part corresponding to the bottom part, and the cavity formed by a part of the mold is a cavity corresponding to the back surface of the bottom part. The console box manufacturing method according to the technical concept (i), wherein the console box is formed to be recessed from the tee portion and delays the flow rate of the resin into the space formed by a part of the mold. Method.

The perspective view which shows the installation state to the vehicle of a console box. The perspective view which shows the console box immediately after shaping | molding. (A) is a rear view which shows the bottom part of a console box. (B) is a perspective view similarly. AA line sectional view in FIG. (A), (b), (c) is a schematic diagram which shows the flow of the resin with which it filled in the cavity. (A), (b), (c) is a schematic diagram which shows the flow of the resin with which it filled in the cavity.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Console box, 6 ... Storage part, 6a, 6b ... Side wall, 6f ... Bottom part, 11 ... Cavity, 12 ... Resin, 19b ... Gate.

Claims (3)

In a method for producing a box-shaped resin molded article having a box body, in which a resin in a dissolved state is filled in a cavity formed inside a mold formed by combining a plurality of molds,
The box is formed to have a bottom, a side wall standing on the periphery of the bottom, and an opening that opens at the upper end of the side wall.
A gate serving as an inlet for filling the resin into the cavity is provided at a position other than the final filling position at which the resin finally flows in the cavity, and at a portion of the mold corresponding to the bottom. Is provided with a gas venting mechanism for releasing the gas in the cavity to the outside of the cavity,
Combining the plurality of molds, the cavity is formed such that the thickness in the cavity corresponding to the side wall gradually decreases from the part corresponding to the upper end of the side wall to the part corresponding to the lower end. ,
Filling the cavity with the resin. A method for producing a box-shaped resin molded product. The position where the gas venting mechanism is provided is a part of the mold corresponding to the bottom,
The flow rate of the resin into the space in the cavity corresponding to the part of the mold where the gas venting mechanism is provided is delayed depending on the structure or state of the mold. A method for producing a box-shaped resin molded product. Due to a part of the mold, the thickness in the cavity corresponding to the part of the mold provided with the degassing mechanism is made thinner than the thickness in the other cavity corresponding to the bottom. The box shape according to claim 2, wherein the flow rate of the resin into the space in the cavity corresponding to the portion of the mold provided with the gas venting mechanism is delayed by forming in such a manner. Manufacturing method of resin molded product.

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