JP2010005995A - Molding die of resin molded body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding die suppressing deflection deformation of a slide core due to injection pressure of a molten resin material in the injection molding, and causing no molding sink in a resin molded body. <P>SOLUTION: The pressure receiving part 11A of a core mold 11 abuts on a mold face of the slide core 13 by mold closing of the core mold 11 and a cavity mold 12. The injection pressure of the molten synthetic resin material acts on the mold face facing the cavity mold 12 of the slide core 13, and the slide core 13 receives the pressing pressure toward the core mold 11. The pressing pressure is received by the pressure receiving part 11A of the core mold 11 to suppress the deflection deformation of the slide core 13. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a molding die for a resin molded body integrally provided with an undercut portion on the back surface.

  In general, many automotive interior materials such as door trims are molded with an appropriate synthetic resin material, and various parts are assembled to the door trim.

  FIG. 5 shows a door trim 1 made of a synthetic resin which is injection-molded by a predetermined mold. A door armrest 2 is integrally bulged and formed on a side surface of the door trim 1 on the vehicle compartment side.

  FIG. 6 shows the door switch unit 3 assembled to the upper surface of the door armrest 2.

  The door switch unit 3 includes a unit main body 4 and an escutcheon 5 for mounting the unit main body 4 on the upper surface of the door armrest 2.

  The escutcheon 5 is made of an appropriate synthetic resin material and is injection-molded by a predetermined mold.

  As shown in FIG. 7, the escutcheon 5 has an opening window 6 for exposing an operation knob (not shown) of the unit main body 4 and the rear surface of the opening window 6 as shown in FIG. A plurality of boss portions 7 for fastening and fixing the unit body 4 are integrally formed in the vicinity.

  When the boss portion 7 has a large projecting length, when the boss portion 7 is directly integrally formed on the back surface of the escutcheon 5, the boss portion 7 having a large volume and a peripheral portion thereof are subjected to injection molding. Due to the difference in the cooling cycle of the synthetic resin material, a distortion generally referred to as “sink” occurs on the design surface which is the outer surface of the escutcheon 5 at the molded portion of the boss portion 7.

  For this reason, as shown in FIG. 8, conventionally, the boss portion 7 is placed on the seat surface 8A of the boss seat 8 via the bridge-shaped boss seat 8 called “Yakura” on the back surface of the escutcheon 5. Are integrally molded. In this way, by providing the boss portion 7 in a state separated from the back surface of the escutcheon 5 via the bridge-shaped boss seat 8, the boss portion 7 forming portion of the escutcheon 5 at the time of injection molding and its peripheral portion are combined. The resin material cooling cycle is substantially the same, and the occurrence of the above-mentioned “sink” is avoided.

  In FIG. 8, reference numeral 9 denotes a hidden clip integrally protruding on the back surface of the escutcheon 5, and the escutcheon 5 is fixedly fixed to the upper surface portion of the door armrest 2.

  Here, the boss seat 8 formed on the back surface of the escutcheon 5 is an undercut portion that intersects with the die-cutting direction of the escutcheon 5. A molding die 10 having a slide core 13 shown in FIG. 9 is used.

  The molding die 10 is disposed in a parting part of the core mold 11 and the cavity mold 12 for molding the escutcheon 5, and the core mold 11 and the cavity mold 12, and becomes an undercut portion on the back surface of the escutcheon 5. And a slide core 13 for forming the boss seat 8.

  The cavity mold 12 is moved up and down with respect to the core mold 11 by a cylinder mechanism or the like (not shown), and is clamped and opened.

  On the other hand, the slide core 13 is slid and moved in a direction orthogonal to the die-cutting direction of the formed escutcheon 5, that is, in the lateral direction indicated by an arrow A in FIG. 9, by a cylinder mechanism or an ejector mechanism (not shown).

The boss seat 8 of the escutcheon 5 and the boss portion 7 on the seat surface 8 </ b> A are formed in a cavity space between the core mold 11 and the slide core 13. Therefore, the slide core 13 is slid laterally outside the mold surface of the core mold 11 before at least the escutcheon 5 is punched upward from the mold surface of the core mold 11 by an ejector pin (not shown). Patent Document 1).
JP 2003-205531 A

  As shown in FIG. 9, when the undercut amount L (the length of the slide core 13 in the sliding direction) of the boss seat 8 formed integrally with the back surface of the escutcheon 5 is large, the die-cutting property of the slide core 13 is taken into consideration. Thus, a required draft angle θ is set for the slide core 13.

  As described above, when the draft angle θ is given to the slide core 13 and the slide core 13 is tapered, the core mold 11 and the cavity mold are separated from the slide core 13 at the time of injection molding of the escutcheon 5. The tip portion of the slide core 13 that has been tapered receives a pressing force as shown by an arrow Fa in FIG. 9B due to the injection pressure of the molten resin material injected into the substantially central portion of the cavity space between And bends and deforms downward (core mold 11 side).

  Then, the escutcheon 5 partially increases in thickness at the bent and deformed tip portion of the slide core 13, and “sink” 5a can be generated on the design surface side (outer surface) of the increased thickness portion for the above-described reason. There is sex.

  Therefore, the present invention provides a molding die that can reliably prevent the slide core 13 from being bent and deformed by the injection pressure of the molten resin material at the time of injection molding and does not cause “sinking” in the resin molded body. Is.

  In the molding die of the present invention, a fixed mold and a movable mold for molding a resin molded body, and a parting portion between the fixed mold and the movable mold, an undercut portion is provided on the back surface of the resin molded body. A pressure core that partially contacts the mold surface of the slide core at a portion corresponding to the undercut portion of the resin molded body. Is the main feature.

  The pressure receiving portion abuts on a mold surface that forms an undercut portion of the slide core by clamping the fixed mold and the movable mold. As a result, the molten synthetic resin material is injected from the gate set at the substantially central portion of the cavity space between the fixed mold and the movable mold, and the injection pressure is either the fixed mold or the movable mold of the slide core. When the slide core receives a pressing force toward one of the fixed mold and the movable mold, the pressing force is applied to the pressure receiving portion of either the fixed mold or the movable mold. Is accepted. As a result, the bending deformation of the slide core due to the injection pressure to either the fixed mold or the movable mold is suppressed, and the thickness corresponding to the slide core of the resin molded body is increased due to the bending deformation of the slide core. It is possible to avoid the occurrence of “sink marks” on the design surface side due to the increased change portion.

  According to the present invention, the pressure receiving portion protruding from one of the fixed mold and the movable mold causes the slide mold to bend into either the fixed mold or the movable mold due to the injection pressure of the slide core at the time of injection molding. Since deformation is restrained, the portion corresponding to the slide core of the resin molded body has an increased change in thickness due to the bending deformation of the slide core, and “sink” occurs on the design surface side. Therefore, a high-quality resin molded body can be molded.

  In the following, an embodiment of the present invention will be described in detail with the same reference numerals assigned to the same components as those in the prior art together with the drawings.

  1 is a partial cross-sectional view showing an embodiment of a molding die according to the present invention, FIG. 2 is a perspective view of a resin molded body molded by the molding die as seen from the back side, and FIG. 3 is a portion of FIG. It is an enlarged view.

  The molding die 10 of this embodiment shown in FIG. 1 is used for injection molding of an escutcheon 5 in the door switch unit 3 as a resin molded body shown in FIGS.

  This escutcheon 5 has the same main structure as the conventional escutcheon 5 shown in FIGS.

  That is, as shown in FIGS. 2 and 3, the escutcheon 5 is injection-molded by a molding die 10 shown in FIG. 1 with an appropriate synthetic resin material.

  The escutcheon 5 has an opening portion 6 for exposing an operation knob (not shown) of the unit main body 4 (the door switch unit 3 and the unit main body 4 are both shown in FIG. 6) in the door switch unit 3. .

  The unit main body 4 is assembled to the back side of the escutcheon 5, and the operation knob is exposed and disposed outside the escutcheon 5 through the open window 6 as described above.

  On the back surface of the escutcheon 5, a plurality of front and rear boss portions 7 for fastening and fixing the unit main body 4 in the vicinity of the open window portion 6 are integrally formed.

  The pair of bosses 7 on the front side of the fenestration part 6 are protrusively provided in proximity to the side edges of the escutcheon 5 in the vehicle width direction, and the pair of boss parts 7 on the rear side of the fenestration part 6 are 5 projecting adjacent to the center in the vehicle width direction.

  Since an operation guide portion 6a for placing a finger on the operation knob of the unit body 4 is formed in the substantially first half portion of the fenestration portion 6 so as to bulge toward the back side of the escutcheon 5, the boss portion 7 In any case, the protruding length is set to be relatively large so that the unit main body 4 does not interfere with the back surface of the operation guide portion 6a.

  When the boss portion 7 having a large protruding length is directly formed integrally with the back surface of the escutcheon 5 as described above, “sink marks” are generated on the design surface (outer surface) of the escutcheon 5 at the portion corresponding to the molding of the boss portion 7 due to the above-described reason. End up.

  Therefore, as shown in the figure, these boss portions 7 are each provided on the back surface of the escutcheon 5 via a bridge-shaped boss seat 8 so as to project on the seat surface 8A of the boss seat 8.

  Since the pair of bosses 7 on the front side of the fenestration part 6 are arranged relatively far apart in the vehicle width direction as described above, the boss seats 8 are independently formed. .

  On the other hand, since the pair of boss portions 7 on the rear side of the window portion 6 are arranged close to each other in the vehicle width direction, one boss seat 8 formed relatively long in the vehicle width direction as shown in the figure. Of the seating surface 8A.

  Since the boss seat 8 serves as an undercut portion that intersects with the die-cutting direction of the escutcheon 5 when the escutcheon 5 is injection-molded, the escutcheon 5 is provided with a slide core 13 shown in FIG. A molding die 10 is used.

  A molding die 10 according to the present embodiment shown in FIG. 1 is a molding-corresponding portion of one boss seat 8 that is formed relatively long in the vehicle width direction on the rear side where a pair of left and right boss portions 7 are adjacent to each other. Is shown.

  The molding die 10 is provided in a core mold 11 as a fixed mold and a cavity mold 12 as a movable mold for molding the escutcheon 5, and a parting portion between the core mold 11 and the cavity mold 12. 5 is provided with a slide core 13 for forming the boss seat 8 serving as an undercut portion.

  In this embodiment, the cavity mold 12 is moved up and down with respect to the core mold 11 by a cylinder mechanism or the like (not shown) to clamp and open the mold.

  On the other hand, the slide core 13 is slid in the lateral direction A perpendicular to the die-cutting direction of the formed escutcheon 5 by a cylinder mechanism (not shown) or by a combination of an ejector mechanism and an angular pin mechanism (not shown). .

  As described above, the boss seat 8 on the rear side is formed relatively long in the vehicle width direction and has a large undercut amount L with respect to the die cutting direction. A draft angle θ of a required angle is set on the mold surface for molding the seat surface 8A of the seat 8.

  The core mold 11 is partially located on the mold surface of the slide core 13 at a portion corresponding to the boss seat 8 of the escutcheon 5, specifically, a portion corresponding to the seat surface 8 A of the boss seat 8. 11 A of pressure receiving parts which contact | abut are protrudingly provided.

  Further, in the present embodiment, the pressure receiving portion 11A of the core mold 11 is tapered between the pair of boss portions 7 and 7 on the distal end side that is tapered by the draft angle θ of the slide core 13 and has a high tendency to bend. It is provided to be located.

  In the molding die 10 of the present embodiment having the above-described configuration, the core mold 11 and the cavity die 12 are clamped so that the pressure receiving portion 11A of the core die 11 has the escalation in the slide core 13. The base surface 8A of the boss seat 8 serving as the undercut portion 5 is brought into contact with the mold surface to be molded.

  The melted synthetic resin material extruded from an extruder not shown in the figure is connected to the cavity space through a gate (not shown) having a hole set in a substantially central portion of the cavity space between the core mold 11 and the cavity mold 12. Is injected into.

  The injection pressure of the melted synthetic resin material acts on the mold surface of the slide core 13 facing the cavity mold 12, and the slide core 13 receives the pressing force Fa toward the core mold 11. Is received by the pressure receiving portion 11A of the core mold 11, and a reaction force Fa ′ with respect to the pressing force Fa is generated.

  As a result, the bending deformation of the slide core 13 toward the core mold 11 due to the injection pressure is suppressed, and the thickness change due to the bending deformation of the slide core 13 is caused in the portion corresponding to the slide core 13 of the escutcheon 5. This prevents the occurrence of “sink marks” on the design surface (outer surface).

  After forming the escutcheon 5, when the cavity mold 12 is opened and the slide core 13 is slid out of the mold surface of the core mold 11, the molded escutcheon 5 is moved by the unillustrated ejector pin. Is taken out more. In addition, the screw hole of the boss | hub part 7 is secondary-processed by a post process.

  As shown in FIGS. 2 and 3, the escutcheon 5 injection-molded by the molding die 10 in this way is provided on the seat surface 8A of the boss seat 8 provided on the back side thereof, with a pair of left and right boss portions 7, 7, an opening 8B corresponding to the outer peripheral shape of the pressure receiving portion 11A of the core mold 11 is formed.

  If the opening 8B is formed long in the vehicle width direction as shown in FIGS. 2 and 3, for example, as long as the strength of the boss seat 8 is not impaired, the amount of resin material used is reduced and the weight of the escutcheon 5 is reduced. Can contribute to cost and cost reduction.

  FIG. 4 shows a modified example of this embodiment. In this modified example, the shape of the pressure receiving portion 11A of the core mold 11 is formed into, for example, an irregular shape of a plus shape, and the opening portion 8B of the boss seat 8 is formed. Is formed as a positive locating hole.

  Therefore, in the case of this modification, the unit body 4 of the door switch unit 3 is provided with a positive locating protrusion 4a corresponding to the opening 8B, so that when the unit body 4 is assembled, By engaging the opening 8B and the locating protrusion 4a, the unit body 4 can be positioned and prevented from rotating, and the fastening work to the bosses 7 and 7 can be easily performed. In FIG. 4, 4 b indicates a bracket portion corresponding to the boss portion 7 of the unit body 4.

  As described above, according to the molding die of the present embodiment, when the core die 11 and the cavity die 12 are clamped, the pressure receiving portion 11A protruding from the core die 11 comes into contact with the die surface of the slide core 13. Thus, the bending of the slide core 13 toward the core mold 11 by the injection pressure during the injection molding of the escutcheon 5 is suppressed.

  As a result, in the portion corresponding to the slide core 13 of the escutcheon 5, an increased change in thickness occurs due to the bending deformation of the slide core 13, and “sink” occurs on the design surface (outer surface). Therefore, high quality escutcheon 5 can be formed.

  In particular, in the present embodiment, the pressure receiving portion 11A of the core mold 11 is provided at a portion corresponding to the tip side formed tapered by the draft angle θ of the slide core 13, and therefore the slide core 13 at the time of injection molding. The bending deformation of can be more reliably suppressed.

  In the above-described embodiment, the escutcheon 5 in the door switch unit 3 mounted on the door trim 1 of the automobile is described as an example of the resin molded body. However, the present invention is not limited to this, and an undercut is formed on the back surface. If it is the resin molding which has a part, it can apply to the shaping | molding and can acquire the effect similar to the above-mentioned.

  Further, the mold 10 is exemplified by a type in which a core mold 11 as a fixed mold and a cavity mold 12 as a movable mold are clamped in the vertical direction and the mold is opened. Of course, the present invention can also be applied to a type that is clamped or opened. Furthermore, although the pressure receiving part 11A is provided in the core mold 11, it goes without saying that it is provided on the cavity mold 12 side depending on the shape of the resin molded product.

Sectional drawing which shows the principal part of one Embodiment of this invention. The perspective view which looked at the resin molded object shape | molded by embodiment shown in FIG. 1 from the back side. The elements on larger scale of the resin molding shown in FIG. The partial expansion perspective view which shows the modification of a resin molding. The perspective view which shows a door trim. The perspective view seen from the back side of the door switch unit with which a door trim is equipped. The perspective view of the escutcheon of a door switch unit. The perspective view which looked at the escutcheon shown in FIG. 7 from the back side. The elements on larger scale which show the molding condition of the resin molding by the conventional metal mold apparatus in steps (A) and (B).

Explanation of symbols

5 ... Escussion (resin molding)
7 ... Boss part 8 ... Boss seat (undercut part)
8A ... Seating surface 10 ... Molding die 11 ... Core mold (fixed mold)
11A ... pressure receiving part 12 ... cavity type (movable type)
13 ... Slide core L ... Undercut amount θ ... Draft angle

Claims (2)

A fixed mold and a movable mold for molding a resin molded body;
A slide core that is provided at a parting portion of the fixed mold and the movable mold and that forms an undercut portion on the back surface of the resin molded body,
In either one of the fixed mold and the movable mold, a pressure receiving portion that partially contacts the mold surface of the slide core protrudes from a portion corresponding to the undercut portion of the resin molded body. Characteristic mold.   The molding die according to claim 1, wherein the pressure receiving portion is provided at a position where the pressure receiving portion abuts on a distal end side that is tapered by a draft of the slide core.

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