JP7042089B2 - Injection molded product - Google Patents

Description

The present invention relates to an injection molded article having ribs.

Synthetic resin molded products by injection molding are often used for products that require complicated curved surface shapes and mass productivity, such as interior parts mounted on the interior surface of a vehicle. In injection molding, generally, a molding process of forming a molding space by molding a fixed mold (cavity) and a movable mold (core) constituting a molding mold and a resin material heated and melted in this molding space are used. An injection process in which injection pressure is applied to fill, a pressure-holding cooling process in which the filled resin is cooled while being pressed and solidified, and a mold opening removal process in which a fixed mold and a movable mold are opened to take out a molded product. And, including. Due to the mold opening, a mold release pin protruding from the movable mold in the opening / closing direction is pressed against the molded product in order to separate it from the fixed mold and take out the molded product in the movable mold.

In the holding pressure cooling step, so-called molding shrinkage occurs in which the volume of the resin shrinks. The molding shrinkage occurs toward the gate, which is the entrance for filling the molding space with the molten resin, and becomes more remarkable as the molded product becomes larger. When the molding die has a recess for forming a rib of a molded product, the rib sticks to the recess due to the molding shrinkage of the resin. This increases the mold release resistance of the ribs, which may damage the ribs or prevent the molded product from being taken out.

The injection-molded article disclosed in Patent Document 1 has ribs extending in a direction intersecting the flow direction of the resin during injection molding. When taking out a molded product during injection molding, multiple mold release pins are pressed against this molded product to apply an average extrusion load to the molded product, preventing damage to the ribs and making it easier to take out the molded product. ..

The injection-molded article shown in FIG. 16 disclosed as a background technique in Patent Document 2 has a shape that is caught in the opening / closing direction of the fixed type and the movable type, that is, an undercut portion. In this case, the molded product cannot be taken out only by opening the fixed mold and the movable mold and protruding the release pin. Therefore, a molding die equipped with a slide top is used.

The slide top is used for molding the undercut portion. When taking out the molded product, the slide piece is slid in the direction intersecting the protrusion direction at the same time as the mold release pin is projected in synchronization with the mold opening. As a result, the slide piece is extracted from the undercut portion. Further, by protruding the release pin, the molded product is taken out from the movable mold.
In a molding die provided with a slide piece, a mold release pin cannot be arranged in the slide area of the slide piece.

Japanese Unexamined Patent Publication No. 11-198165 Japanese Unexamined Patent Publication No. 2005-178066

In the molded product shown in FIG. 16 of Patent Document 2, when a rib is formed at a position facing the slide region of the slide piece during injection molding, the release pin cannot be pressed around the rib. , The release pin must be pressed against the area away from the rib. Therefore, the balance of the extrusion load of the release pin applied to the molded product becomes unbalanced, which causes the molded product to be deformed. In particular, when the extending direction of the rib is a direction intersecting the flow direction of the resin during injection molding, the rib sticks to the rib forming recess of the molding die due to the molding shrinkage, and the mold release resistance increases. Therefore, the rib may be damaged or the molded product may not be taken out.

In order to solve the above problems, the present invention is an injection molded product in which a main rib extending in a direction intersecting the flow direction of the resin during injection molding is formed in a region where a mold release pin cannot be applied during injection molding. Auxiliary ribs extending in a direction intersecting the flow direction of the resin are provided in a region where a mold release pin can be applied during injection molding on the upstream side or the downstream side of the main rib in the flow direction of the resin. It is characterized by being formed.

According to the above configuration, in addition to the main rib, an auxiliary rib is formed, and the auxiliary rib is attached to the auxiliary rib forming recess of the molding die at the time of molding shrinkage, so that the main rib is attached to the main rib forming recess. Can be weakened. In addition, a release pin can be applied around the auxiliary rib. Therefore, the molded product can be satisfactorily taken out from the molding die after injection molding without damaging the main rib.

One aspect of the present invention is a pillar trim as an injection-molded product, which has a base wall portion and both side wall portions and has a U-shaped cross section, and a gate at one end in the longitudinal direction during injection molding. A position is set, an undercut portion is formed on one side wall portion between the gate position and the other end in the longitudinal direction, and the base wall portion has the main rib at a position in the longitudinal direction corresponding to the undercut portion. Is formed so as to extend in the lateral direction, and the auxiliary rib extending in the lateral direction is formed in the base wall portion at a position separated from the main rib in the longitudinal direction.

According to the above configuration, at the time of injection molding, the undercut portion is formed by the slide piece, and the main rib at the position corresponding to the undercut portion faces the slide area of the slide piece, and is around the main rib. The release pin cannot be pressed. However, by forming the auxiliary ribs, the sticking of the main ribs to the molding die during molding shrinkage is weakened, and by applying a mold release pin around the auxiliary ribs, the injection-molded pillar trim is taken out from the molding die. , Can be done well without damaging the main rib.

According to the present invention, it is possible to provide an injection-molded product that can be satisfactorily taken out from a molding die without damaging the ribs even if the ribs are formed in a region where the mold release pin cannot be applied during injection molding. ..

It is a perspective view which looked at the pillar trim which concerns on one Embodiment of this invention from the back side. It is sectional drawing which shows the shape of the molding die at the part along the line II-II of FIG. (C) indicates a state in which the molded product is taken out.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 2 . In this embodiment, the present invention is applied to a pillar trim that covers the passenger compartment side of a pillar of a vehicle.
The pillar trim 10 shown in FIG. 1 is arranged between the front seat and the rear seat on the right side on the passenger compartment side of a pillar panel (body panel) (not shown). A seatbelt adjuster mechanism (not shown) for adjusting the support height of the seatbelt is arranged between the pillar panel and the pillar trim 10.

The pillar trim 10 is configured by injection molding a resin such as polypropylene (PP). The pillar trim 10 extends in the vertical direction along the pillar panel, has a U-shaped cross section, and is connected to the front wall 11 (base wall portion) substantially orthogonal to the vehicle width direction and rearward. It has a rear wall 12 (side wall portion) facing forward and a front wall 13 (side wall portion) facing forward connected to the front wall 11. An opening 14 is formed in the front wall 11. A gate position 15 at the time of injection molding is set at the upper end portion of the rear wall 13 on the outer side in the vehicle width direction.

The seatbelt adjuster mechanism has an adjuster cover (not shown) that is slidably supported in the vertical direction on the back side (outside of the vehicle) of the pillar trim 10. The adjuster cover closes the opening 14 of the pillar trim 10, and the adjuster cover is formed with an outlet. The seat belt is led out to the vehicle interior through the outlet of the adjuster cover and the opening 14 of the pillar trim 10.

As shown in FIGS. 1 and 2, on the back side (outside of the vehicle) of the front wall 11 of the pillar trim 10, support ribs 16 and 17 for supporting the adjuster cover are provided in the width direction (on the upper and lower sides of the opening 14). It is formed so as to extend in the lateral direction). The upper support rib 16 is arranged substantially in the center of the front wall 11, while the lower support rib 17 (main rib) is arranged closer to the rear wall 12. The support rib 17 has an inclined portion 17a on the rear wall 12 side that inclines toward the outside of the vehicle as it advances toward the front wall 13, and is flat so as to be connected to the inclined portion 17a and a portion having a substantially constant height continues toward the front wall 13. Do part 17b.

These support ribs 16 and 17 are covered with a cushioning material (not shown) made of a non-woven fabric or the like, and the cushioning material is fixed to the surface region adjacent to the support ribs 16 and 17 by welding or adhesion. In this cushioning material, the portions corresponding to the support ribs 16 and 17 are in contact with the adjuster cover (not shown) in a compressed state. This cushioning material prevents the generation of abnormal noise between the support ribs 16 and 17 and the adjuster cover.

An auxiliary rib 18 is formed on the front wall 11 below the support rib 17. As will be described later, the auxiliary rib 18 plays a role of weakening the sticking of the support rib 17 to the molding die due to molding shrinkage during injection molding of the pillar trim 10.

The auxiliary rib 18 has an L-shape, and has a base portion 18a extending in the longitudinal direction of the pillar trim 10 at substantially the center of the front wall 11 and a support rib extending from the upper end of the base portion 18a in the lateral direction and the front wall 13 direction. It has an facing portion 18b facing the 17th. The facing portion 18b is parallel to the support rib 17. The protruding height of the facing portion 18b from the front wall 11 is formed to be slightly higher than the flat portion 17b of the support rib 17.

As shown in FIG. 1, a shock absorbing rib 20 is formed integrally with the pillar trim 10 on the back surface of the rear wall 12 of the pillar trim 10. The shock absorbing rib 20 is for the safety of the occupant, and is narrowed by the pillar trim 10 and the pillar panel (not shown) as the head of the occupant in the rear seat hits the pillar trim 10 in the event of a vehicle collision. It absorbs the impact on the head by plastically deforming.

The shock absorbing rib 20 has two vertical rib portions 21 and 22 extending in the vertical direction along the outer side edge of the rear wall 12, and an upper rib connected to the upper end of the vertical rib portion 21 and the lower end of the vertical rib portion 22, respectively. It has a portion 23 and a lower rib portion 24. These rib portions 23 and 24 extend toward the vehicle interior and reach the rear end portion of the front wall 11.

A protruding portion 25 projecting toward the vehicle interior is provided between the vertical rib portions 21 and 22. The protruding portion 25 has a U-shape with the outside of the vehicle open. The protruding portion 25 has a vertical portion 26 substantially parallel to the vertical rib portions 21 and 22, and an upper side portion 27 and a lower side portion 28 extending from the upper and lower ends of the vertical portion 26 toward the outside of the vehicle.

As shown in FIG. 1, the shock absorbing rib 20 is provided at a position corresponding to the support rib 17 of the front wall 11 in the longitudinal direction of the pillar trim 10, and more specifically, the vertical rib portion 22 is a support rib. It is in the position corresponding to 17.

The pillar trim 10 is molded by a molding die that is molded from the vehicle interior side and the vehicle outside as described later. The shock absorbing rib 20 protrudes from the rear wall 12 in the direction intersecting the opening direction (vehicle width direction) of the molding die (vehicle length direction), and the molded pillar trim 10 is taken out in the opening direction. It is a hindering shape, a so-called undercut part.

Next, a mold for molding the pillar trim 10 will be described.
FIG. 2 shows a molding die 30 for molding the pillar trim 10 in a cross section corresponding to a portion along the line II-II of FIG. The pillar trim 10 is molded by a known injection molding method in which a molten resin P is injected into the molding die 30 by an injection molding machine (not shown).

The molding die 30 is composed of a fixed die 40 and a movable die 50, and the movable die 50 can be opened and closed in a direction corresponding to the vehicle width direction of the pillar trim 10. In the state where the fixed mold 40 and the movable mold 50 shown in FIG. 2A are combined, the molding die 30 is formed with a molding space 31 in which the pillar trim 10 is molded.

The fixed mold 40 is formed with a recess 41 corresponding to the shape of the surface (the surface on the vehicle interior side) of the pillar trim 10. Although not shown in FIG. 2, the gate serving as the entrance of the molten resin P to the recess 41 is provided at one end of the recess 41, and is the outer upper end portion of the rear wall 12 of the pillar trim 10 shown in FIG. 1 in the vehicle width direction. It corresponds to the gate position 15.

The movable mold 50 has a concave-convex shape corresponding to the shape of the back surface (the outer surface of the vehicle) of the pillar trim 10 including the outside of the shock absorbing rib 20, and also has a slide piece 60 that can be slanted with respect to the movable mold 50. Have.

The slide piece 60 has a protrusion 61 having a shape corresponding to the inner shape of the shock absorbing rib 20 at the end of the pillar trim 10 on the rear wall 12 side in a direction intersecting the opening / closing direction of the molding die 30. The protrusion 61 forms the inner surface of the shock absorbing rib 20. The slide piece 60 is formed with a support rib forming recess 62 for forming the support rib 17 of the pillar trim 10 on the surface on the fixed mold 40 side.

The slide piece 60 is fixed from the movable mold 50 while sliding in the direction approaching the front wall 13 from the rear wall 12 of the pillar trim 10, that is, in the depth direction orthogonal to the paper surface of FIG. 2 when the mold 30 is opened. It sticks out to the mold 40 side. The slide direction of the slide piece 60 at this time coincides with the extending direction of the support rib 17.

The movable mold 50 at a position separated downward from the support rib forming recess 62 in the longitudinal direction of the molding space 31 is provided with an auxiliary rib forming recess 51 for forming the auxiliary rib 18.

The movable mold 50 is provided with a mold release pin 70 for taking out the pillar trim 10 molded in the molding space 31 near the auxiliary rib forming recess 51. The release pin 70 is slidable in parallel with the opening / closing movement direction of the movable mold 50, and protrudes from the movable mold 50 toward the fixed mold 40 when the mold 30 is opened.

Next, injection molding of the pillar trim 10 using the molding die 30 will be described.
As shown in FIG. 2A, the molding die 30 is injected with the molten resin P from an injection molding machine (not shown) with the fixed mold 40 and the movable mold 50 closed. The injected molten resin P is injected into the molding space 31 through a gate (gate position 15 at the upper end of the pillar trim 10) (not shown) and flows in the longitudinal direction thereof. The filled molten resin P is cooled and solidified. At that time, the front surface of the pillar trim 10 is molded by the fixed mold 40, and the back surface of the pillar trim 10 is molded by the movable mold 50. In the shock absorbing rib 20, the outer side is formed by the movable mold 50, and the inner side is formed by the slide piece 60. The support rib 17 is formed by the support rib forming recess 62. The auxiliary rib 18 is formed by the auxiliary rib forming recess 51.

After that, as shown in FIG. 2B , the movable mold 50 is moved to open the mold 30. The pillar trim 10 is separated from the fixed mold 40 and attached to the movable mold 50. At this time, as shown in FIG. 2C , the release pin 70 is projected toward the fixed mold 40, and at the same time, the slide piece 60 is projected toward the fixed mold 40, and the pillar trim 10 is projected from the rear wall 12 to the front wall 13. Slide in the direction closer to.
As a result, the slide piece 60 comes out of the shock absorbing rib 20. Further, the release pin 70 is projected to allow the auxiliary rib 18 to escape from the auxiliary rib forming recess 51, and the support rib 17 to escape from the support rib forming recess 62. As a result, the pillar trim 10 which is a molded product is taken out from the movable mold 50.

In the injection molding of the pillar trim 10, when the molten resin P filled in the molding space 31 is solidified, the molded pillar trim 10 shrinks toward the gate position 15 along the longitudinal direction thereof. As a result, the support rib 17 sticks to the support rib forming recess 62. The support rib 17 extends in the lateral direction of the pillar trim 10, that is, in a direction intersecting the flow direction of the molten resin P and the contraction direction of the resin, and the sticking is strengthened. Therefore, the mold release resistance of the support rib 17 from the support rib forming recess 62 increases.

In this embodiment, the auxiliary rib 18 is arranged below the support rib 17 and on the downstream side in the flow direction of the molten resin P. The auxiliary rib 18 has an opposed portion 18b extending in the lateral direction of the pillar trim 10, so that the auxiliary rib 18 is attached to the auxiliary rib forming recess 51 by molding shrinkage. As a result, the sticking of the support rib 17 to the support rib forming recess 62 is weakened, and the mold release resistance of the support rib 17 from the support rib forming recess 62 is reduced.

Further, since the support rib forming recess 62 is provided in the slide piece 60, the release pin cannot be applied near the support rib 17, but in this embodiment, the auxiliary rib 18 that weakens the sticking of the support rib 17 is weakened. The release pin 70 can be applied near the. As a result, the molded pillar trim 10 can be satisfactorily taken out without damaging the support rib 17.

The present invention is not limited to the above embodiment, and various modifications can be adopted without departing from the gist thereof.
Auxiliary ribs may be provided on the upstream side in the flow direction of the molten resin.
The height of protrusion of the facing portion of the auxiliary rib from the front wall may be the same as that of the flat portion of the support rib, or may be lowered.
In the above embodiment, the facing portion of the auxiliary rib is formed parallel to the support rib, but it may be formed in the intersecting direction.

The present invention can be applied to an injection molded product having ribs.

10 pillar trim (injection molded product)
11 Front wall 12 Rear wall 13 Front wall 15 Gate position 17 Support rib (main rib)
18 Auxiliary rib 20 Shock absorbing rib (undercut part)
70 Release Pin P Molten Resin

Claims (2)

In the molding space formed by the fixed mold and the movable mold, the melted and injected synthetic resin material is injected from the gate, and after the injection molded product having the undercut portion is molded, the fixed mold and the above are described. The movable mold is opened, and the release pin provided on the movable mold is projected toward the fixed mold and the fixed mold side in the mold opening direction of the movable mold, and the injection molded product is extruded. It ’s a device,
A part of the movable mold is formed to form an undercut portion of the injection-molded product, and when the mold release pin extrudes the injection-molded product, it protrudes diagonally with respect to the protrusion direction of the mold release pin. It is provided with a slide piece that slides against the injection-molded product while extruding the injection-molded product and exits from the undercut portion. Has some auxiliary ribs and
A main rib forming recess for molding the main rib was formed on the side of the slide piece for extruding the injection-molded product, and the main rib forming recess extended in the slide direction of the slide piece and melted from the gate. It intersects the flow direction of the synthetic resin material and
In the movable mold other than the slide piece, the portion facing the molding space is located on the upstream side or the downstream side in the flow direction with respect to the main rib forming recess and at a position close to the slide piece. An auxiliary rib forming recess for forming the rib is formed, and the auxiliary rib forming recess extends in substantially the same direction as the main rib forming recess, intersects the flow direction, and is arranged in the vicinity of the mold release pin. A mold device for injection molding, which is characterized by being A method for manufacturing an injection-molded article using the injection-molding die apparatus according to claim 1.
The process of forming the molding space by molding the fixed mold and the movable mold, and
The process of injecting the melted and injected synthetic resin material from the gate and pouring it into the molding space to fill it.
By cooling and solidifying the synthetic resin material, the undercut portion is formed by the slide piece, the main rib is formed by the main rib forming recess, and the auxiliary rib is formed by the auxiliary rib forming recess. A step of weakening the sticking of the synthetic resin material to the main rib forming recess by sticking the synthetic resin material shrinking toward the gate to the auxiliary rib forming recess.
The fixed mold and the movable mold are opened, and the slide piece is projected diagonally to the molded injection molded product, and the release pin is projected and pressed near the auxiliary rib, whereby the slide is formed. A step of removing the top from the undercut portion, releasing the main rib and the auxiliary rib from the main rib forming recess and the auxiliary rib forming recess, respectively, and taking out the injection molded product from the movable mold.
A method for manufacturing an injection-molded product, which is characterized by being provided with.

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