JP2004175031A - Injection-molded article with opening and method for molding it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a secondary processing such as a touch-up coating or the like to reduce a processing cost by changing a position of a weldline formed at a confluent point of resin flows flowing so as to hold an opening between the flows to an inconspicuous position, in a method for molding an injection-molded article with the opening. <P>SOLUTION: In a door pocket (the injection-molded article) 20 with the opening 21, either one of a hollow structure, a ribbed structure and a thick-walled structure by a gas injection techinique is employed at least on one side among both sides holding the opening 21 and a resin fluidity accelerating structure largely ensuring the cross-sectional area of a flow path is applied thereby. By this constitution, the weldline W formed at the confluent point of the resin flows is changed to a position not confirmed by a crew to eliminate a touch-up coating process. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is applicable to interior parts for automobiles such as door pockets, rear pillar garnishes, etc., and relates to an injection molded product having an opening and a molding method thereof. The present invention relates to an injection-molded article having an opening capable of eliminating secondary processing and reducing product cost, and a molding method thereof.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an automotive interior component to be installed in a vehicle, an injection molded product using a general-purpose resin such as a polypropylene (PP) resin is often used in consideration of cost, moldability, physical properties, and the like.
[0003]
For example, FIG. 10 shows an automobile door trim 1 mounted on the indoor side of a door panel of a vehicle. A door pocket 2 also having an armrest function is attached to a substantially central portion of the surface of the automobile door trim 1. I have. The door pocket 2 is made of an injection-molded product of PP resin, and has an opening 3 on the front side so as to enhance the design and to check the internal storage equipment (for example, see Patent Document 1). .
[0004]
Although not shown in the patent document, as shown in FIG. 12, a door pocket 2 having upper and lower two rows of openings 3a and 3b on the front side of the door pocket 2 has also been proposed and implemented.
[0005]
The gate position of the door pocket 2 shown in FIGS. 11 and 12 is set so that the resin flows along the longitudinal direction of the opening 3 in consideration of the resin flow during injection molding. It is generally set to one edge of the side (indicated by the symbol G in the figure).
[0006]
[Patent Document 1]
JP-A-10-244880 (page 3, FIG. 2, FIG. 3)
[0007]
[Problems to be solved by the invention]
As described above, conventionally, in an injection molded product such as the door pocket 2 having the opening 3, the gate is provided at one end on the left and right sides of the door pocket 2 so that the resin flows along the longitudinal direction of the opening 3. Since the G is set, in the door pocket 2 shown in FIG. 11, the respective flows branching so as to sandwich the opening 3 from both sides merge at the most remote point with respect to the gate G. In addition, a weld line W is formed from the right end of the opening 3 in the drawing to the right end edge of the door pocket 2, and there is a problem that the appearance performance of the door pocket 2 is significantly reduced.
[0008]
As a countermeasure, it has been pointed out that secondary processing such as touch-up painting is required so as to cover the weld line W, resulting in an increase in processing cost and an increase in product cost.
[0009]
This means that as shown in FIG. 12, when the two openings 3a and 3b are set up and down, the resin flow along the longitudinal direction of the opening 3 is branched into three with the two openings 3a and 3b interposed therebetween. Resin flow is obtained. Therefore, two weld lines W are formed from the right ends of the two openings 3a and 3b to the right end of the door pocket 2, and the disadvantage that the appearance is reduced more than in FIG. 11 is remarkable.
[0010]
The present invention has been made in view of such circumstances, and eliminates secondary processing such as touch-up painting by controlling the formation of weld lines, which are inevitable, in an injection-molded article having an opening. It is an object of the present invention to provide an injection-molded article having an opening capable of reducing the production cost by doing so and a molding method therefor.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has an opening that is formed into a required shape by injecting and filling a molten resin into a cavity defined between a fixed mold and a movable mold. An injection-molded product, a resin flow promoting structure is adopted on at least one side of both sides along the longitudinal direction of the opening, so that a plurality of resin flows along the longitudinal direction of the opening across the opening merge. It is characterized in that the formation location of the weld line formed at the location where it is formed can be changed.
[0012]
Here, the injection molded product having an opening can be applied to a door pocket mounted on a door trim, a rear pillar garnish mounted around an opera window of a vehicle, and the like.
[0013]
Further, as the resin fluidity promoting structure, a hollow structure by a gas injection method, a structure provided with ribs, a thick-wall structure, or the like can be considered.
[0014]
According to the present invention, a hollow structure formed by a gas injection method on at least one of the two sides sandwiching the opening, a rib-attached structure having ribs extending along the longitudinal direction of the opening, or an increase in the thickness of the general portion. By adopting a thicker wall structure, the resin flow can be extremely accelerated.In the past, the weld line was inevitably formed at the farthest point from the gate, but it partially flowed. The position of the weld line can be changed by speeding up the process.
[0015]
Therefore, by locally accelerating the resin flow, a weld line can be set in a place where the occupant cannot easily see it, and in such a case, a secondary process such as touch-up painting for hiding the weld line can be omitted. .
[0016]
Further, when a hollow structure formed by a gas injection method is employed as the resin fluidity promoting structure, deformation and surface sink caused by heat shrinkage distortion can be prevented, and strong rigidity can be maintained.
[0017]
Next, in the method of molding an injection-molded article having an opening according to the present invention, the molten resin is injected and filled into a cavity defined between the fixed mold and the movable mold through a gate of the mold. A method for molding an injection-molded article having an opening for molding an injection-molded article having a required shape with an opening, wherein the gate is set at one side edge of the injection-molded article on the longitudinal end side of the opening; By setting the flow path cross-sectional area of at least one side of both sides along the longitudinal direction to be large, it is possible to prevent the resin flow from joining at the edge opposite to the gate at the opening and to adjust the flowability of the resin. , The position at which the weld line is formed is controlled.
[0018]
Here, the gate is set at a point extending from the longitudinal end of the opening to the terminal side of the injection molded article along the longitudinal direction of the opening so that the resin flows along the longitudinal direction of the opening.
[0019]
Therefore, according to the method for molding an injection-molded article having an opening according to the present invention, at least one side of both sides along the longitudinal direction of the opening has a flow path cross-sectional area in order to promote fluidity of the resin. Since it is set large, the formation position of the weld line formed at the point where the branched resin flows join can be changed to an arbitrary position by changing the cross-sectional area.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of an injection-molded article having an opening according to the present invention and a molding method thereof will be described by exemplifying a door pocket mounted on a door trim.
[0021]
FIG. 1 is a front view showing a configuration of a door trim equipped with a door pocket to which the present invention is applied, FIG. 2 is a front view of the door pocket, FIG. 3 is a sectional view showing the configuration of the door pocket, and FIG. FIG. 5 is a schematic view showing the overall configuration of a molding die used in the molding method of FIG. 5, FIG. 5 is a plan view of a movable mold in the molding die, and FIG. FIG. 7 is an explanatory view showing the flow of resin when resin filling is completed in the molding process of the door pocket. FIGS. 8 and 9 are sectional views showing modified embodiments of the door pocket to which the present invention is applied. .
[0022]
First, an embodiment of the present invention will be described with reference to FIGS. 1 to 3, an automobile door trim 10 is attached to a room inside a door panel (not shown) via a fixing means such as a clip (not shown). An armrest 11 is mounted so as to rest on the inside, an inside handle escutcheon 12 is mounted on the front side of a middle part above the armrest 11, and a speaker grill 13 is provided on the lower front side of the door trim 10. Further, below the armrest 11 of the door trim 10, a door pocket 20 made of an injection-molded article capable of storing various equipment or a road map is attached.
[0023]
The door pocket 20 is made of an injection-molded body of PP resin. The door pocket 20 is not a main part to be attached to the door trim 10 and is not shown in the figure. A mounting boss is erected, and is fitted to the door trim 10 through conventional fixing means such as by fixing it with a screw or the like from the back side of the door trim 10 so as to match the mounting hole formed corresponding to the mounting boss. Have been.
[0024]
By the way, the door pocket 20 in the present embodiment is formed of an injection-molded product having openings 21 (upper opening 21a and lower opening 21b) in two upper and lower rows, has good design characteristics, and has a shape of the opening 21. In consideration of this, although a gate is provided at a point indicated by reference numeral G in FIG. 2, a weld line W formed farthest from the gate G conventionally has a door pocket 20 which is inconspicuous from an occupant in the present invention. The feature is that it is set on the lower side of.
[0025]
In order to form a weld line W on the lower side of the door pocket 20, in the present embodiment, a hollow portion extending along the longitudinal direction of the opening 21 along the upper side of each of the upper and lower two rows of openings 21a and 21b. 22 is employed. Note that a gas injection method is used to form the hollow portion 22.
[0026]
That is, as shown in FIG. 3, the outer peripheral portion 23 of the hollow portion 22 has a depth dimension a × a height dimension b set to 10 mm × 15 mm. Along with this, the wide cross-sectional area (a × b dimension) of the outer peripheral portion 23 becomes the resin flow path area, and the resin flow is greatly promoted in this portion. Is formed.
[0027]
Therefore, in the door pocket 20 of this embodiment, the weld line W is changed to the lower side of the inconspicuous door pocket 20 by providing the hollow portion 22 using the gas injection method along the longitudinal direction of the opening 21. be able to.
[0028]
Accordingly, since the weld line W is not noticeable by the occupant, secondary processing such as touch-up painting can be eliminated, and the processing cost can be reduced. In addition, since the weld line W has the hollow portion 22 structure, deformation due to heat shrinkage distortion is caused. Can be effectively suppressed, and furthermore, there is no occurrence of sink marks or the like on the product surface. In addition, the hollow portion 22 structure enhances the rigidity, does not deform even when the door pocket 20 is gripped and operated when closing the door, and is convenient in terms of usability.
[0029]
Next, an outline of the overall configuration of the molding die 30 for molding the door pocket 20 will be described with reference to FIGS. The molding die 30 has a structure in which two symmetrical door pockets 20 to be mounted on left and right door trims can be taken.
[0030]
That is, as shown in FIG. 4, the molding die 30 is roughly composed of a fixed die 40 and a movable die 50. The fixed mold 40 has a fixed mold plate 42 attached to a lower surface of a fixed attachment plate 41, and a manifold 43 for supplying molten resin from an injection machine (not shown) is attached to a substantially central portion in FIG. ing.
[0031]
On the other hand, in the movable mold 50, a movable mold plate 53 is supported by a movable mounting plate 51 via a spacer block 52, and when the fixed mold 40 and the movable mold 50 are closed, the fixed mold 50 is fixed. By injecting and filling the molten resin into the cavity C defined between the mold plate 42 and the movable mold plate 53, the symmetrical door pocket 20 is formed into a required shape.
[0032]
In the movable mold 50, an ejector plate 54 is provided in a space formed by the spacer block 52, and the ejector plate 54 performs a predetermined stroke up and down operation by an ejector plate driving cylinder (not shown). In FIG. 4, the sprue lock pin 55 and the ejector pin (not shown) are pushed up to function to smoothly remove the molded product after molding. Further, the resin supplied into the cavity C defined between the fixed mold plate 42 and the movable mold plate 53 is supplied from the manifold 43 through the sprue 60, the runner 61, and the gate 62. Injection filling. The movable-side mold 50 has a movable-side mounting plate 51 connected to a press ram (not shown), and is driven by the drive of the press ram to clamp and open the mold 30.
[0033]
By the way, the door pocket 20 in the present embodiment employs a hollow portion 22 structure using a gas injection method in order to locally increase the fluidity of the resin. As shown in FIG. 5, a gas injection mechanism 70 and a spill-out mechanism 80 are provided. That is, after the molten resin is injected and filled into the cavity C through the sprue 60, the runner 61, and the gate 62, the gas is injected from the gas injection mechanism 70, and the excess resin is discharged from the spill-out mechanism 80. The hollow portion 22 is formed at a portion indicated by a dotted line in FIG.
[0034]
Next, the point that the formation position of the weld line W can be changed by forming the hollow portion 22 in the door pocket 20 according to the present embodiment will be described with reference to FIGS. FIG. 6 shows the flow of molten resin at the initial stage of injection filling into the cavity C defined between the fixed mold 40 and the movable mold 50, and the shape of the cavity C is a door pocket. In order to correspond to the product shape of No. 20, the molten resin takes a branched flow at the openings 21a and 21b, and the flow of the molten resin becomes four flows of (A), (B), (C) and (D). .
[0035]
In this case, the important flows are (A) and (B), and the resin flows (A) and (B) each have a channel cross-sectional area of depth dimension a × height dimension b = 10 mm × 15 mm. Therefore, at the initial stage of filling the molten resin, the resin flows (A) and (B) are in a state where the resin flow is remarkably accelerated along the length direction of the opening 21.
[0036]
As shown in FIG. 7, although the resin flows (A) and (B) merge near the longitudinal end of the opening 21a on the upper side, they merge and go further downward, so that substantially the weld is formed. No line W is formed. When the filling of the molten resin is completed, the resin flows (A) and (B) and the resin flow (C) merge at the lower portion of the door pocket 20 in the cavity C, and a weld line W is formed at the junction. Will be.
[0037]
As described above, before the hollow portion 22 is formed along the longitudinal direction of the openings 21a and 21b, this portion has a wide flow path cross-sectional area, so that the resin flows (A) and (B) flow. The weld line W can be controlled to an arbitrary position by utilizing the fluidity of the resin.
[0038]
Therefore, if the weld line W is set on the lower side of the door pocket 20, it is difficult for the occupant to see the weld line W, so that secondary processing such as touch-up painting for eliminating the weld line W becomes unnecessary, and the number of processing steps can be reduced.
[0039]
Next, FIGS. 8 and 9 show another embodiment in which the present invention is applied to a door pocket 20. In FIG. Three ribs 25 are formed to project. Therefore, since the rib 25 is provided on the back surface side along the opening 21, the fluidity of the resin in this portion is increased, and each resin flow flowing above the upper and lower openings 21 a and 21 b is similar to the above-described embodiment. Then, the resin flows into the lower side of the lower opening 21b, and the resin flow merges at this point, so that the weld line W can be controlled to an inconspicuous place.
[0040]
Thus, in the door pocket 20 having the ribs 25 shown in FIG. 8 as well, the weld line W can be set at the lower side of the door pocket 20 as described above, and the weld line W is located at a location that is inconspicuous from the occupant's line of sight. Because it can be set, secondary processing such as touch-up painting is not required, processing cost can be reduced, and rigidity is enhanced by the rib 25, so even if the door is closed by grasping this part, deformation It has excellent rigidity and can maintain the initial shape for a long period of time.
[0041]
Further, FIG. 9 shows a door pocket 20 in which a thick portion 26 is set on the upper side along the longitudinal direction of the upper and lower openings 21a and 21b, and the thick portion 26 speeds up the fluidity of the resin in this portion. By forming the weld line W on the lower side of the door pocket 20, secondary processing such as touch-up painting can be omitted. In the structure in which the thick portion 26 shown in FIG. 9 is provided, there is a tendency that shrinkage distortion easily occurs and the weight increases, but the gas injection mechanism and the spill-out mechanism used in the gas injection method have a disadvantage. Since there is no need for this and no mold processing for forming the ribs 25 is required, there is an advantage that mold equipment and mold processing can be simplified.
[0042]
【The invention's effect】
As described above, according to the present invention, in an injection-molded article having an opening and a method of molding the same, at least one of the two sides along the longitudinal direction of the opening has a hollow structure formed by a gas injection method, By adopting either the rib-attached structure along the wall or the thick-walled structure, it is possible to accelerate the fluidity of the resin locally with respect to the resin flow in the general part. It is possible to arbitrarily control the formation position of the weld line formed in the place, and to set the weld line in an inconspicuous part. There is an effect that the processing is not required, the processing cost can be reduced, and the cost can be reduced.
[0043]
Furthermore, when the fluidity of the resin is accelerated by adopting the hollow structure by the gas injection method, the hollow structure is lightweight, and it is lightweight and deforms due to heat shrinkage distortion, and sinks on the product surface. Is not generated, and the rigidity can be enhanced.
[Brief description of the drawings]
FIG. 1 is a front view showing a door trim equipped with a door pocket, which is one embodiment of an injection molded product according to the present invention.
FIG. 2 is a front view showing a door pocket which is an embodiment of the injection molded product according to the present invention.
FIG. 3 is a sectional view taken along line III-III in FIG. 2;
FIG. 4 is a schematic diagram showing the overall configuration of a molding die used to mold the door pocket shown in FIG.
5 is a plan view showing a cavity of a movable mold in the molding mold shown in FIG. 4;
FIG. 6 is an explanatory view showing a resin flow at an initial stage of resin filling in a door pocket forming step shown in FIG. 2;
FIG. 7 is an explanatory diagram showing a resin flow when resin filling is completed in a door pocket forming step shown in FIG. 2;
FIG. 8 is a cross-sectional view showing a configuration of another embodiment of the injection molded product according to the present invention.
FIG. 9 is a cross-sectional view showing a configuration of another embodiment of the injection molded product according to the present invention.
FIG. 10 is a front view showing a conventional automobile door trim.
FIG. 11 is a front view showing a conventional door pocket.
FIG. 12 is a front view showing a conventional door pocket.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Car door trim 11 Armrest 12 Inside handle escutcheon 13 Speaker grill 20 Door pocket 21 Opening 21a Upper side opening 21b Lower side opening 22 Hollow part 23 Outer part 24 Molding body 25 Rib 26 Thick part 30 Molding die 40 Fixed side metal Mold 42 Fixed mold 50 Movable mold 53 Movable mold 60 Sprue 61 Runner 62 Gate 70 Gas injection mechanism 80 Spillout mechanism C Cavity W Weld line

Claims (5)

The cavity (C) defined between the fixed mold (40) and the movable mold (50) has an opening (21) formed into a required shape by injection filling with molten resin. An injection molded product (20),
By adopting a resin fluidity promoting structure on at least one side of both sides along the longitudinal direction of the opening (21), a plurality of resin flows along the longitudinal direction of the opening (21) across the opening (21). An injection-molded article having an opening, characterized in that a weld line (W) formed at a position where the two meet can be changed. The injection molded article having an opening according to claim 1, wherein the resin fluidity promoting structure is a hollow portion (22) structure formed by a gas injection method. The resin fluidity promoting structure is a structure provided with a rib (25) in which one or more ribs (25) extending along the longitudinal direction of the opening (21) are provided on the back surface of the molded article main body (24). An injection-molded article having an opening according to claim 1. The injection having an opening according to claim 1, wherein the resin fluidity promoting structure is a thick part (26) structure which is thickened with respect to the thickness of the general part of the injection molded product (20). Molding. The molten resin is injected and filled into the cavity (C) defined between the fixed mold (40) and the movable mold (50) through the gate (62) of the molding mold (30). In a method for molding an injection molded product (20) having an opening (21) for molding an injection molded product (20) having a required shape having (21),
The gate (62) is set at one side edge of the injection molded product (20) on the terminal side in the longitudinal direction of the opening (21), and at least one of the flow paths on both sides along the longitudinal direction of the opening (21). By setting the cross-sectional area large, it is possible to prevent the resin flow from converging at the edge of the opening (21) opposite to the gate (62), and to form the weld line (W) by adjusting the flowability of the resin. A method for molding an injection-molded article having an opening, characterized by controlling a position.

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